Publications by authors named "Derrick C Wan"

192 Publications

Mechanical Strain Drives Myeloid Cell Differentiation Toward Pro-Inflammatory Subpopulations.

Adv Wound Care (New Rochelle) 2021 Jul 17. Epub 2021 Jul 17.

Stanford University, Surgery, 257 Campus Drive West, GK-201, Stanford, California, United States, 94305-5148;

Objective: After injury, humans and other mammals heal by forming fibrotic scar tissue with diminished function, and this healing process involves the dynamic interplay between resident cells within the skin and cells recruited from the circulation. Recent studies have provided mounting evidence that external mechanical forces stimulate intracellular signaling pathways to drive fibrotic processes.

Innovation: While most studies have focused on studying mechanotransduction in fibroblasts, recent data suggest that mechanical stimulation may also shape the behavior of immune cells, referred to as "mechano-immunomodulation". However, the effect of mechanical strain on myeloid cell recruitment and differentiation remains poorly understood and has never been investigated at the single cell level.

Approach: In this study, we utilized a three-dimensional (3D) in vitro culture system that permits the precise manipulation of mechanical strain applied to cells. We cultured myeloid cells and used single cell RNA-sequencing to interrogate the effects of strain on myeloid differentiation and transcriptional programming.

Results: Our data indicate that myeloid cells are indeed mechanoresponsive, with mechanical stress influencing myeloid differentiation. Mechanical strain also upregulated a cascade of inflammatory chemokines, most notably from the Ccl family.

Conclusion: Further understanding of how mechanical stress affects myeloid cells in conjunction with other cell types in the complicated, multicellular milieu of wound healing may lead to novel insights and therapies for the treatment of fibrosis.
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http://dx.doi.org/10.1089/wound.2021.0036DOI Listing
July 2021

A Systematic Review of Mandibular Distraction Osteogenesis Versus Orthodontic Airway Plate for Airway Obstruction Treatment in Pierre Robin Sequence.

Cleft Palate Craniofac J 2021 Jun 2:10556656211011886. Epub 2021 Jun 2.

Hagey Laboratory for Pediatric Regenerative Medicine, 10624Stanford University School of Medicine, Stanford, CA, USA.

Objective: Mandibular distraction osteogenesis (MDO) is frequently performed to address airway obstruction in patients with Pierre Robin sequence (PRS), though more recently the technique of orthodontic airway plating (OAP) has gained traction. We aimed to evaluate OAP compared to MDO for airway obstruction in PRS.

Design: A systematic literature search across PubMed, Embase, and Google Scholar identified all studies published in English, which involved MDO or any form of OAP as treatments for PRS. All relevant articles were reviewed in detail and reported on, adhering to PRISMA guidelines.

Main Outcome Measures: Airway (tracheostomy avoidance, decannulation rate), feeding (full oral feeding tolerance).

Results: Literature search identified 970 articles, of which 42 MDO studies and 9 OAP studies met criteria for review. A total of 1159 individuals were treated with MDO, and 322 individuals were treated with OAP. Primary outcomes appear similar for MDO and OAP at face value; however, this must be interpreted with different pretreatment contexts in mind.

Conclusions: Orthodontic airway plating may be considered for airway obstruction in PRS, as some airway-related and feeding-related outcomes appear similar with MDO, per existing evidence in the literature. However, since PRS severity differed between studies, OAP cannot be uniformly considered a replacement for MDO. Further research is required to more comprehensively assess these treatment modalities inclusive of metrics that allow for direct comparison.
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http://dx.doi.org/10.1177/10556656211011886DOI Listing
June 2021

The Impact of Coagulopathy on Clinical Outcomes following Microsurgical Breast Reconstruction.

Plast Reconstr Surg 2021 Jul;148(1):14e-18e

From the Division of Plastic and Reconstructive Surgery and the Hagey Laboratory for Pediatric Regenerative Medicine, Stanford University School of Medicine.

Summary: Autologous breast reconstruction has evolved considerably from pedicled muscle-based approaches to microsurgical perforator-based techniques. Patients with documented coagulopathy, however, remain a particularly challenging population. The authors present their experience in microsurgical breast reconstruction in patients with coagulopathy and discuss their treatment protocol. A prospectively maintained database was queried for patients with coagulopathy who underwent microsurgical breast reconstruction between 2016 and 2019. Information regarding patient demographics, type of coagulopathy, and anticoagulation regimen were retrieved, and clinical outcomes were investigated. Nineteen patients who underwent 34 microsurgical breast reconstructions with free abdominal flaps were included in the study. The most common coagulopathy was factor V Leiden [n = 7 (38.6 percent)]. Nine patients (47.4 percent) developed thrombotic complications (the majority occurring intraoperatively); notably, arterial and venous thrombosis in four (21.1 percent) and two patients (10.5 percent), respectively. Postoperative thrombotic complications included pulmonary embolism [n = 2 (10.5 percent)] and flap congestion secondary to venous thrombosis [two flaps (5.9 percent)]. Only one flap loss was observed secondary to delayed venous thrombosis on postoperative day 6 (2.9 percent). The anticoagulation regimen in the majority of patients consisted of intraoperative intravenous administration of heparin (2000 U [bolus]) followed by a 5-day heparin infusion at 500 U/hour [n = 10 (52.6 percent)]. The high rate of thrombotic complications in patients with coagulopathy who underwent microsurgical breast reconstruction is contrasted by a low flap loss rate. Although coagulopathy is a risk factor for thrombotic complications, successful microsurgical breast reconstruction is still possible in the majority of patients.
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http://dx.doi.org/10.1097/PRS.0000000000008099DOI Listing
July 2021

Readability of Online Patient Information Relating to Cleft Palate Surgery.

Cleft Palate Craniofac J 2021 May 7:10556656211013177. Epub 2021 May 7.

Hagey Laboratory for Pediatric Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.

Objective: It is important for health care education materials to be easily understood by caretakers of children requiring craniofacial surgery. This study aimed to analyze the readability of Google search results as they pertain to "Cleft Palate Surgery" and "Palatoplasty." Additionally, the study included a search from several locations globally to identify possible geographic differences.

Design: Google searches of the terms "Cleft Palate Surgery" and "Palatoplasty" were performed. Additionally, searches of only "Cleft Palate Surgery" were run from several internet protocol addresses globally.

Main Outcome Measures: Flesch-Kincaid Grade Level and Readability Ease, Gunning Fog Index, Simple Measure of Gobbledygook (SMOG) index, and Coleman-Liau Index.

Results: Search results for "Cleft Palate Surgery" were easier to read and comprehend compared to search results for "Palatoplasty." Mean Flesch-Kincaid Grade Level scores were 7.0 and 10.11, respectively ( = .0018). Mean Flesch-Kincaid Reading Ease scores were 61.29 and 40.71, respectively ( = .0003). Mean Gunning Fog Index scores were 8.370 and 10.34, respectively ( = .0458). Mean SMOG Index scores were 6.84 and 8.47, respectively ( = .0260). Mean Coleman-Liau Index scores were 12.95 and 15.33, respectively ( = .0281). No significant differences were found in any of the readability measures based on global location.

Conclusions: Although some improvement can be made, craniofacial surgeons can be confident in the online information pertaining to cleft palate repair, regardless of where the search is performed from. The average readability of the top search results for "Cleft Palate Surgery" is around the seventh-grade reading level (US educational system) and compares favorably to other health care readability analyses.
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http://dx.doi.org/10.1177/10556656211013177DOI Listing
May 2021

Preventing activation in fibroblasts yields wound regeneration without scarring.

Science 2021 04;372(6540)

Department of Surgery, Division of Plastic and Reconstructive Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.

Skin scarring, the end result of adult wound healing, is detrimental to tissue form and function. lineage-positive fibroblasts (EPFs) are known to function in scarring, but lineage-negative fibroblasts (ENFs) remain poorly characterized. Using cell transplantation and transgenic mouse models, we identified a dermal ENF subpopulation that gives rise to postnatally derived EPFs by activating expression during adult wound healing. By studying ENF responses to substrate mechanics, we found that mechanical tension drives activation via canonical mechanotransduction signaling. Finally, we showed that blocking mechanotransduction signaling with either verteporfin, an inhibitor of Yes-associated protein (YAP), or fibroblast-specific transgenic YAP knockout prevents activation and promotes wound regeneration by ENFs, with recovery of skin appendages, ultrastructure, and mechanical strength. This finding suggests that there are two possible outcomes to postnatal wound healing: a fibrotic response (EPF-mediated) and a regenerative response (ENF-mediated).
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http://dx.doi.org/10.1126/science.aba2374DOI Listing
April 2021

Nonsurgical Orthodontic Airway Plate Treatment for Newborns With Robin Sequence.

Cleft Palate Craniofac J 2021 Apr 13:10556656211007689. Epub 2021 Apr 13.

Division of Plastic and Reconstructive Surgery, Department of Surgery, 10624Stanford University School of Medicine, Palo Alto, CA, USA.

Despite promising outcomes for >50 years, nonsurgical orthodontic airway plates (OAP) are only infrequently offered for babies with Robin sequence in a few parts of the world. This article demonstrates possibility of providing functional improvement using an OAP to help these babies overcome their functional and structural difficulties on their own. Two consecutively treated cases are presented exemplifying that OAP treatment that had originated from Europe is reproducible and effective in an institution in the United States.
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http://dx.doi.org/10.1177/10556656211007689DOI Listing
April 2021

Craniofacial and Long Bone Development in the Context of Distraction Osteogenesis.

Plast Reconstr Surg 2021 01;147(1):54e-65e

From the Department of Surgery, Division of Plastic and Reconstructive Surgery, and the Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine.

Background: Bone retains regenerative potential into adulthood, and surgeons harness this plasticity during distraction osteogenesis. The underlying biology governing bone development, repair, and regeneration is divergent between the craniofacial and appendicular skeleton. Each type of bone formation is characterized by unique molecular signaling and cellular behavior. Recent discoveries have elucidated the cellular and genetic processes underlying skeletal development and regeneration, providing an opportunity to couple biological and clinical knowledge to improve patient care.

Methods: A comprehensive literature review of basic and clinical literature regarding craniofacial and long bone development, regeneration, and distraction osteogenesis was performed.

Results: The current understanding in craniofacial and long bone development and regeneration is discussed, and clinical considerations for the respective distraction osteogenesis procedures are presented.

Conclusions: Distraction osteogenesis is a powerful tool to regenerate bone and thus address a number of craniofacial and appendicular skeletal deficiencies. The molecular mechanisms underlying bone regeneration, however, remain elusive. Recent work has determined that embryologic morphogen gradients constitute important signals during regeneration. In addition, striking discoveries have illuminated the cellular processes underlying mandibular regeneration during distraction osteogenesis, showing that skeletal stem cells reactivate embryologic neural crest transcriptomic processes to carry out bone formation during regeneration. Furthermore, innovative adjuvant therapies to complement distraction osteogenesis use biological processes active in embryogenesis and regeneration. Additional research is needed to further characterize the underlying cellular mechanisms responsible for improved bone formation through adjuvant therapies and the role skeletal stem cells play during regeneration.
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http://dx.doi.org/10.1097/PRS.0000000000007451DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7773036PMC
January 2021

Prrx1 Fibroblasts Represent a Pro-fibrotic Lineage in the Mouse Ventral Dermis.

Cell Rep 2020 11;33(6):108356

Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA; Institute for Stem Cell Biology and Regenerative Medicine, Stanford School of Medicine, Stanford, CA 94305, USA. Electronic address:

Fibroblast heterogeneity has been shown within the unwounded mouse dorsal dermis, with fibroblast subpopulations being identified according to anatomical location and embryonic lineage. Using lineage tracing, we demonstrate that paired related homeobox 1 (Prrx1)-expressing fibroblasts are responsible for acute and chronic fibroses in the ventral dermis. Single-cell transcriptomics further corroborated the inherent fibrotic characteristics of Prrx1 fibroblasts during wound repair. In summary, we identify and characterize a fibroblast subpopulation in the mouse ventral dermis with intrinsic scar-forming potential.
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http://dx.doi.org/10.1016/j.celrep.2020.108356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7742512PMC
November 2020

ALK-positive compound Spitz nevus with extensive perineural and intraneural neurotropism.

J Cutan Pathol 2021 Jan 8;48(1):154-159. Epub 2020 Nov 8.

Department of Pathology, Stanford Medicine, Stanford, California, USA.

Historically recognized by their characteristic histopathologic features, Spitz neoplasms are now known to be molecularly defined by mutually exclusive recurrent abnormalities that cause activation of the MAPK pathway. Spitz neoplasms with ALK rearrangements frequently demonstrate polypoid growth with a plexiform arrangement of nested, fusiform melanocytes in intersecting fascicles. Although neurotropism has been described in indolent Spitz neoplasms, this feature is not frequently mentioned in publications on histopathologic assessment of this group of melanocytic tumors. Here, we present an unusual case of a 3-year-old female with an ALK-positive compound Spitz nevus with extensive perineural and intraneural neurotropism occurring on the vermilion border of the lower lip.
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http://dx.doi.org/10.1111/cup.13890DOI Listing
January 2021

Characterization of Diabetic and Non-Diabetic Foot Ulcers Using Single-Cell RNA-Sequencing.

Micromachines (Basel) 2020 Aug 28;11(9). Epub 2020 Aug 28.

Department of Surgery, Division of Plastic and Reconstructive Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.

Recent advances in high-throughput single-cell sequencing technologies have led to their increasingly widespread adoption for clinical applications. However, challenges associated with tissue viability, cell yield, and delayed time-to-capture have created unique obstacles for data processing. Chronic wounds, in particular, represent some of the most difficult target specimens, due to the significant amount of fibrinous debris, extracellular matrix components, and non-viable cells inherent in tissue routinely obtained from debridement. Here, we examined the feasibility of single cell RNA sequencing (scRNA-seq) analysis to evaluate human chronic wound samples acquired in the clinic, subjected to prolonged cold ischemia time, and processed without FACS sorting. Wound tissue from human diabetic and non-diabetic plantar foot ulcers were evaluated using an optimized 10X Genomics scRNA-seq platform and analyzed using a modified data pipeline designed for low-yield specimens. Cell subtypes were identified informatically and their distributions and transcriptional programs were compared between diabetic and non-diabetic tissue. 139,000 diabetic and non-diabetic wound cells were delivered for 10X capture after either 90 or 180 min of cold ischemia time. cDNA library concentrations were 858.7 and 364.7 pg/µL, respectively, prior to sequencing. Among all barcoded fragments, we found that 83.5% successfully aligned to the human transcriptome and 68% met the minimum cell viability threshold. The average mitochondrial mRNA fraction was 8.5% for diabetic cells and 6.6% for non-diabetic cells, correlating with differences in cold ischemia time. A total of 384 individual cells were of sufficient quality for subsequent analyses; from this cell pool, we identified transcriptionally-distinct cell clusters whose gene expression profiles corresponded to fibroblasts, keratinocytes, neutrophils, monocytes, and endothelial cells. Fibroblast subpopulations with differing fibrotic potentials were identified, and their distributions were found to be altered in diabetic vs. non-diabetic cells. scRNA-seq of clinical wound samples can be achieved using minor modifications to standard processing protocols and data analysis methods. This simple approach can capture widespread transcriptional differences between diabetic and non-diabetic tissue obtained from matched wound locations.
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http://dx.doi.org/10.3390/mi11090815DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7570277PMC
August 2020

Articular cartilage regeneration by activated skeletal stem cells.

Nat Med 2020 10 17;26(10):1583-1592. Epub 2020 Aug 17.

Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA.

Osteoarthritis (OA) is a degenerative disease resulting in irreversible, progressive destruction of articular cartilage. The etiology of OA is complex and involves a variety of factors, including genetic predisposition, acute injury and chronic inflammation. Here we investigate the ability of resident skeletal stem-cell (SSC) populations to regenerate cartilage in relation to age, a possible contributor to the development of osteoarthritis. We demonstrate that aging is associated with progressive loss of SSCs and diminished chondrogenesis in the joints of both mice and humans. However, a local expansion of SSCs could still be triggered in the chondral surface of adult limb joints in mice by stimulating a regenerative response using microfracture (MF) surgery. Although MF-activated SSCs tended to form fibrous tissues, localized co-delivery of BMP2 and soluble VEGFR1 (sVEGFR1), a VEGF receptor antagonist, in a hydrogel skewed differentiation of MF-activated SSCs toward articular cartilage. These data indicate that following MF, a resident stem-cell population can be induced to generate cartilage for treatment of localized chondral disease in OA.
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http://dx.doi.org/10.1038/s41591-020-1013-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7704061PMC
October 2020

Delivery of Human Stromal Vascular Fraction Cells on Nanofibrillar Scaffolds for Treatment of Peripheral Arterial Disease.

Front Bioeng Biotechnol 2020 17;8:689. Epub 2020 Jul 17.

Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, United States.

Cell therapy for treatment of peripheral arterial disease (PAD) is a promising approach but is limited by poor cell survival when cells are delivered using saline. The objective of this study was to examine the feasibility of aligned nanofibrillar scaffolds as a vehicle for the delivery of human stromal vascular fraction (SVF), and then to assess the efficacy of the cell-seeded scaffolds in a murine model of PAD. Flow cytometric analysis was performed to characterize the phenotype of SVF cells from freshly isolated lipoaspirate, as well as after attachment onto aligned nanofibrillar scaffolds. Flow cytometry results demonstrated that the SVF consisted of 33.1 ± 9.6% CD45 cells, a small fraction of CD45/CD31 (4.5 ± 3.1%) and 45.4 ± 20.0% of CD45/CD31/CD34 cells. Although the subpopulations of SVF did not change significantly after attachment to the aligned nanofibrillar scaffolds, protein secretion of vascular endothelial growth factor (VEGF) significantly increased by six-fold, compared to SVF cultured in suspension. Importantly, when SVF-seeded scaffolds were transplanted into immunodeficient mice with induced hindlimb ischemia, the cell-seeded scaffolds induced a significant higher mean perfusion ratio after 14 days, compared to cells delivered using saline. Together, these results show that aligned nanofibrillar scaffolds promoted cellular attachment, enhanced the secretion of VEGF from attached SVF cells, and their implantation with attached SVF cells stimulated blood perfusion recovery. These findings have important therapeutic implications for the treatment of PAD using SVF.
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http://dx.doi.org/10.3389/fbioe.2020.00689DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7380169PMC
July 2020

Fibroblast Heterogeneity in and Its Implications for Plastic and Reconstructive Surgery: A Basic Science Review.

Plast Reconstr Surg Glob Open 2020 Jun 23;8(6):e2927. Epub 2020 Jun 23.

Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, Calif.

Fibroblasts' integral role in tissue development, maintenance, and disease represents a fast-growing field of basic science research. Although fibroblasts were long thought to be a homogeneous cell population, recent research has illuminated the unforeseen complexity of these cells, giving rise to the rapidly expanding research field of "fibroblast heterogeneity." Fibroblasts play a critical role in states of tissue fibrosis such as skin scarring, which affects hundreds of millions of patients annually and causes severe aesthetic, developmental, and functional morbidity. Beyond scarring, major organ fibrosis is an enormous public health concern responsible for nearly half of all deaths in the United States. Because fibrosis is a conserved response to tissue damage in all organs, the study of fibroblasts throughout the body may help us to understand their role in the conditions most relevant to plastic and reconstructive surgery-for instance, skin scarring (eg, from burns, traumatic lacerations, or surgical incisions), "pathological" scarring (hypertrophic scars, keloids), and capsular contracture. Here, we present a basic science review of fibroblast heterogeneity in wound healing, cancer, organ fibrosis, and human dermal architecture. The field of fibroblast heterogeneity is young, and many of the insights discussed have yet to be translated clinically. However, plastic surgeons stand in a unique position to bridge these discoveries into clinical realities. We hope this information can spur readers to consider both what questions in plastic surgery can be studied from the lens of fibroblast heterogeneity, and how these preclinical insights can be translated to improving care of our patients.
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http://dx.doi.org/10.1097/GOX.0000000000002927DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7339369PMC
June 2020

Prophylactic treatment with transdermal deferoxamine mitigates radiation-induced skin fibrosis.

Sci Rep 2020 07 23;10(1):12346. Epub 2020 Jul 23.

Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic Surgery, Department of Surgery, Stanford University School of Medicine, 257 Campus Drive, Stanford, CA, 94305-5148, USA.

Radiation therapy can result in pathological fibrosis of healthy soft tissue. The iron chelator deferoxamine (DFO) has been shown to improve skin vascularization when injected into radiated tissue prior to fat grafting. Here, we evaluated whether topical DFO administration using a transdermal drug delivery system prior to and immediately following irradiation (IR) can mitigate the chronic effects of radiation damage to the skin. CD-1 nude immunodeficient mice were split into four experimental groups: (1) IR alone (IR only), (2) DFO treatment for two weeks after recovery from IR (DFO post-IR), (3) DFO prophylaxis with treatment through and post-IR (DFO ppx), or (4) no irradiation or DFO (No IR). Immediately following IR, reactive oxygen species and apoptotic markers were significantly decreased and laser doppler analysis revealed significantly improved skin perfusion in mice receiving prophylactic DFO. Six weeks following IR, mice in the DFO post-IR and DFO ppx groups had improved skin perfusion and increased vascularization. DFO-treated groups also had evidence of reduced dermal thickness and collagen fiber network organization akin to non-irradiated skin. Thus, transdermal delivery of DFO improves tissue perfusion and mitigates chronic radiation-induced skin fibrosis, highlighting a potential role for DFO in the treatment of oncological patients.
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http://dx.doi.org/10.1038/s41598-020-69293-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7378074PMC
July 2020

The antifibrotic adipose-derived stromal cell: Grafted fat enriched with CD74+ adipose-derived stromal cells reduces chronic radiation-induced skin fibrosis.

Stem Cells Transl Med 2020 11 20;9(11):1401-1413. Epub 2020 Jun 20.

Hagey Laboratory for Pediatric Regenerative Medicine, Department of Surgery, Division of Plastic Surgery, Stanford University School of Medicine, Stanford, California, USA.

Fat grafting can reduce radiation-induced fibrosis. Improved outcomes are found when fat grafts are enriched with adipose-derived stromal cells (ASCs), implicating ASCs as key drivers of soft tissue regeneration. We have identified a subpopulation of ASCs positive for CD74 with enhanced antifibrotic effects. Compared to CD74- and unsorted (US) ASCs, CD74+ ASCs have increased expression of hepatocyte growth factor, fibroblast growth factor 2, and transforming growth factor β3 (TGF-β3) and decreased levels of TGF-β1. Dermal fibroblasts incubated with conditioned media from CD74+ ASCs produced less collagen upon stimulation, compared to fibroblasts incubated with media from CD74- or US ASCs. Upon transplantation, fat grafts enriched with CD74+ ASCs reduced the stiffness, dermal thickness, and collagen content of overlying skin, and decreased the relative proportions of more fibrotic dermal fibroblasts. Improvements in several extracellular matrix components were also appreciated on immunofluorescent staining. Together these findings indicate CD74+ ASCs have antifibrotic qualities and may play an important role in future strategies to address fibrotic remodeling following radiation-induced fibrosis.
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http://dx.doi.org/10.1002/sctm.19-0317DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7581454PMC
November 2020

CD34+CD146+ adipose-derived stromal cells enhance engraftment of transplanted fat.

Stem Cells Transl Med 2020 11 15;9(11):1389-1400. Epub 2020 Jun 15.

Hagey Laboratory for Pediatric Regenerative Medicine, Department of Surgery, Division of Plastic Surgery, Stanford University School of Medicine, Stanford, California, USA.

Fat grafting is a surgical technique able to reconstruct and regenerate soft tissue. The adipose-derived stromal cells (ASCs) within the stromal vascular fraction are believed to drive these beneficial effects. ASCs are increasingly recognized to be a heterogeneous group, comprised of multiple stem and progenitor subpopulations with distinct functions. We hypothesized the existence of an ASC subpopulation with enhanced angiogenic potential. Human ASCs that were CD34+CD146+, CD34+CD146-, or CD34+ unfractionated (UF) were isolated by flow cytometry for comparison of expression of proangiogenic factors and endothelial tube-forming potential. Next, lipoaspirate was enriched with either CD34+CD146+, CD34+CD146-, CD34+ UF ASCs, or was not enriched, and grafted beneath the scalp skin of immunodeficient CD-1 Nude mice (10 000 cells/200 μL/graft). Fat retention was monitored radiographically more than 8 weeks and fat grafts were harvested for histological assessment of quality and vascularization. The CD34+CD146+ subpopulation comprised ~30% of ASCs, and exhibited increased expression of vascular endothelial growth factor and angiopoietin-1 compared to CD34+CD146- and CD34+ UF ASCs, and increased expression of fibroblast growth factor-2 compared to CD34+CD146- ASCs. The CD34+CD146+ subpopulation exhibited enhanced induction of tube-formation compared to CD34+CD146- ASCs. Upon transplantation, fat enriched CD34+CD146+ ASCs underwent less resorption and had improved histologic quality and vascularization. We have identified a subpopulation of CD34+ ASCs with enhanced angiogenic effects in vitro and in vivo, likely mediated by increased expression of potent proangiogenic factors. These findings suggest that enriching lipoaspirate with CD34+CD146+ ASCs may enhance fat graft vascularization and retention in the clinical setting.
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http://dx.doi.org/10.1002/sctm.19-0195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7581443PMC
November 2020

Saethre-Chotzen Syndrome: A Report of 7 Patients and Review of the Literature.

Ann Plast Surg 2020 09;85(3):251-255

Division of Plastic and Reconstructive Surgery, Department of Surgery, University of California Los Angeles Medical Center, Los Angeles, CA.

Introduction: Saethre-Chotzen syndrome is a genetic condition characterized by craniofacial and limb anomalies, with craniosynostosis (mainly coronal) being the most frequent craniofacial finding. Cranial and facial deformities can be extremely variable requiring individualization of treatment strategies. We present our case series to highlight clinical findings, treatment philosophy, and challenges facing Saethre-Chotzen patients.

Methods: A retrospective review was performed on records of patients given a diagnosis of Saethre-Chotzen syndrome at the University of California Los Angeles (UCLA) Craniofacial Clinic (n = 7) between 1980 and 2010. Patients with complete records were included in this study, and review of demographic data, clinical findings, surgical interventions and postoperative follow-up, and stability were performed.

Results: Seven patients (1 male and 6 female) were included in this study. The average age at which the patients were first seen was 6.5 years. Suture involvement was bicoronal (n = 6) and unicoronal (n = 1). There was 1 patient having superimposed metopic synostosis, and there was another patient having Kleeblattschädel deformity. Previous procedures performed for patients before establishing care at UCLA were strip craniectomy (n = 2) and fronto-orbital advancement (n = 2). All patients (n = 7) had fronto-orbital advancements at UCLA. Other skeletal operations included the following: redo forehead advancement and contouring (n = 3), monobloc advancement (n = 1), and LeFort III distraction (n = 1). Five patients reached skeletal maturity, and 2 patients received LeFort I advancement for class III malocclusion, one of which also required a bilateral sagittal split osteotomy of the mandible.

Conclusion: Clinical presentation and severity of deformity in Saethre-Chotzen syndrome are variable. Our current report reviews our treatment strategies and illustrates the predominance of cranial and upper face deformities and frequent need for redo surgeries to address forehead asymmetry in this group of syndromic craniosynostosis patients.
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http://dx.doi.org/10.1097/SAP.0000000000002391DOI Listing
September 2020

"Tissues in a Dish": A Review of Organoids in Plastic Surgery.

Plast Reconstr Surg Glob Open 2020 Apr 29;8(4):e2787. Epub 2020 Apr 29.

Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, Calif.

Organoids are in vitro miniaturized organ models-or, colloquially, "organs in a dish." These 3-dimensional, multicellular structures are classically derived from pluripotent or multipotent stem cells. When guided by tissue-specific molecular factors, these cells exhibit self-organizing abilities that allow them to accurately recapitulate the architecture and function of the organ of interest. Organoid technology is a rapidly expanding field that endows researchers with an unprecedented ability to recreate, study, and manipulate complex biologic processes in vitro. When compared with standard 2- and 3-dimensional culture systems, which rely on co-culturing pre-established cell types, organoids provide a more biomimetic model with which to study the intercellular interactions necessary for in vivo organ function and architecture. Organoids have the potential to impact all avenues of medicine, including those fields most relevant to plastic and reconstructive surgery such as wound healing, oncology, craniofacial reconstruction, and burn care. In addition to their ability to serve as a novel tool for studying human-specific disease, organoids may be used for tissue engineering with the goal of developing biomimetic soft-tissue substitutes, which would be especially valuable to the plastic surgeon. Although organoids hold great promise for the field of plastic surgery, technical challenges in creating vascularized, multilineage organoids must be overcome to allow for the integration of this technology in clinical practice. This review provides a brief history of the organoid, highlights its potential clinical applications, discusses certain limitations, and examines the impact that this technology may have on the field of plastic and reconstructive surgery.
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http://dx.doi.org/10.1097/GOX.0000000000002787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7209840PMC
April 2020

Pelvic/Perineal Reconstruction: Time to Consider the Anterolateral Thigh Flap as a First-line Option?

Plast Reconstr Surg Glob Open 2020 Apr 24;8(4):e2733. Epub 2020 Apr 24.

Division of Plastic and Reconstructive Surgery, Stanford University Medical Center, Palo Alto, Calif.

Background: Abdominoperineal resection (APR) and pelvic exenteration continue to be common procedures for the treatment of colorectal malignancy. The workhorse flap for reconstruction in these instances has been the vertical rectus abdominis myocutaneous flap. The associated donor site morbidity, however, cannot be ignored. Here, we provide a review of the literature and present the senior author's (A.M.) experience using the pedicled anterolateral thigh (ALT) flap for reconstruction of soft tissue defects following APR and pelvic exenteration.

Methods: Patients who underwent pelvic/perineal reconstruction with pedicled ALT flaps between 2017 and 2019 were included in the study. Parameters of interest included age, gender, body mass index, comorbidities, history of radiation, extent of ablative surgery, and postoperative complication rate.

Results: A total of 23 patients (16 men and 7 women) with a median age and body mass index of 66 years (inter-quartile range [IQR]: 49-71 years) and 24.9 kg/m (IQR: 24.2-26.7 kg/m) were included in the study, respectively. Thirteen (56.5%) patients presented with rectal cancer, 5 (21.7%) with anal squamous cell carcinoma (SCC), 4 (17.4%) with Crohn's disease, and 1 (4.3%) with Paget's disease. Nineteen patients (82.6%) received neoadjuvant radiation. Nine (39.1%) patients experienced 11 complications (2 major and 9 minor). The most common complication was partial perineal wound dehiscence (N = 6 [26.1%]). Stable soft tissue coverage was achieved in all but one patient.

Conclusions: The ALT flap allows for stable soft tissue coverage following APR and pelvic exenteration without being associated with abdominal donor site morbidity. Consideration to its use as a first-line reconstructive option should be given in pelvic/perineal reconstruction.
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http://dx.doi.org/10.1097/GOX.0000000000002733DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7209827PMC
April 2020

Compounding Benefits of Sentinel Lymph Node Biopsy for Perineal Melanoma: A Population-Based Retrospective Cohort Analysis.

Ann Plast Surg 2020 05;84(5S Suppl 4):S257-S263

From the Division of Plastic and Reconstructive Surgery, Stanford University Medical Center, Stanford University, Palo Alto, CA.

Introduction: Sentinel lymph node biopsy (SLNB) in the treatment of melanoma is known to provide valuable prognostic information. However, there is no literature describing an overall or disease-specific survival (DDS) benefit of SLNB. In the perineum, melanoma is often more advanced at presentation with current treatment guidelines translated from nonanatomic specific melanoma. As a result, there is little understanding surrounding the role of SLNB in melanoma of the perineum. Our objective is to better understand the therapeutic benefits of SLNB in perineal melanoma.

Methods: The Surveillance, Epidemiology, and End Results program is a large population-based cancer registry including survival data from millions of patients in the United States. The registry was used to generate patient data for analysis from 2004 to 2016. Inclusion criteria included melanoma of the perineum; Breslow depth of 0.80 mm or greater and less than 0.80 mm with ulceration; SLNB or no intervention; clinically negative nodal disease; and available overall survival data.

Results: For 879 patients from 2004 to 2016 with perineal melanoma, significant predictors of reduced survival include older than 75 years, Clark level IV-V, Breslow depth of greater than 4.00 mm, positive ulceration status, regional and distant nodal micrometastases, and clinically positive nodes on presentation. Aggregates for overall survival (OS) and disease-specific survival (DSS) were improved with implementation of SLNB. The 5-year survival rates with SLNB versus no SLNB were 54.0% and 43.0% for OS (P = 0.001) and 57.8% and 53.1% for DSS (P = 0.044). Stratification by Breslow depth yielded significant OS and DSS advantage for greater than 1.00 to 2.00 mm (21.3% benefit, P =0.021, and 16.8% benefit, P = 0.044) and greater than 4.00 mm (30.3% benefit, P = 0.005, and 21.0% benefit, P = 0.007) Breslow depths.

Conclusions And Relevance: Sentinel lymph node biopsy may provide therapeutic benefits in addition to prognostic information for melanoma of the perineum through an increase in 5-year OS.
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http://dx.doi.org/10.1097/SAP.0000000000002388DOI Listing
May 2020

Cryopreserved human skin allografts promote angiogenesis and dermal regeneration in a murine model.

Int Wound J 2020 Aug 30;17(4):925-936. Epub 2020 Mar 30.

Hagey Laboratory for Pediatric and Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University, Stanford, California, USA.

Cryopreserved human skin allografts (CHSAs) are used for the coverage of major burns when donor sites for autografts are insufficiently available and have clinically shown beneficial effects on chronic non-healing wounds. However, the biologic mechanisms behind the regenerative properties of CHSA remain elusive. Furthermore, the impact of cryopreservation on the immunogenicity of CHSA has not been thoroughly investigated and raised concerns with regard to their clinical application. To investigate the importance and fate of living cells, we compared cryopreserved CHSA with human acellular dermal matrix (ADM) grafts in which living cells had been removed by chemical processing. Both grafts were subcutaneously implanted into C57BL/6 mice and explanted after 1, 3, 7, and 28 days (n = 5 per group). A sham surgery where no graft was implanted served as a control. Transmission electron microscopy (TEM) and flow cytometry were used to characterise the ultrastructure and cells within CHSA before implantation. Immunofluorescent staining of tissue sections was used to determine the immune reaction against the implanted grafts, the rate of apoptotic cells, and vascularisation as well as collagen content of the overlaying murine dermis. Digital quantification of collagen fibre alignment on tissue sections was used to quantify the degree of fibrosis within the murine dermis. A substantial population of live human cells with intact organelles was identified in CHSA prior to implantation. Subcutaneous pockets with implanted xenografts or ADMs healed without clinically apparent rejection and with a similar cellular immune response. CHSA implantation largely preserved the cellularity of the overlying murine dermis, whereas ADM was associated with a significantly higher rate of cellular apoptosis, identified by cleaved caspase-3 staining, and a stronger dendritic cell infiltration of the murine dermis. CHSA was found to induce a local angiogenic response, leading to significantly more vascularisation of the murine dermis compared with ADM and sham surgery on day 7. By day 28, aggregate collagen-1 content within the murine dermis was greater following CHSA implantation compared with ADM. Collagen fibre alignment of the murine dermis, correlating with the degree of fibrosis, was significantly greater in the ADM group, whereas CHSA maintained the characteristic basket weave pattern of the native murine dermis. Our data indicate that CHSAs promote angiogenesis and collagen-1 production without eliciting a significant fibrotic response in a xenograft model. These findings may provide insight into the beneficial effects clinically observed after treatment of chronic wounds and burns with CHSA.
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http://dx.doi.org/10.1111/iwj.13349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7949424PMC
August 2020

Commentary: Accelerated chronic skin changes without allograft vasculopathy: A 10-year outcome report after face transplantation.

Surgery 2020 06 20;167(6):999-1000. Epub 2020 Mar 20.

Department of Surgery, University of Alabama at Birmingham School of Medicine, Birmingham, AL.

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http://dx.doi.org/10.1016/j.surg.2020.02.011DOI Listing
June 2020

Beneath the Surface: A Review of Laser Remodeling of Hypertrophic Scars and Burns.

Adv Wound Care (New Rochelle) 2019 Apr 3;8(4):168-176. Epub 2019 Apr 3.

Hagey Laboratory for Pediatric Regenerative Medicine, Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, California.

Hypertrophic scars, keloids, and burn injuries of the skin have a significant impact on patients' lives and impact the health care system tremendously. Treating skin wounds and lesions can be challenging, with a variety of choices available for treatment. Scar and burn managements range from invasive, surgical options such as scar excision to less invasive, nonsurgical alternatives such as laser therapy or topical drug application. Laser treatment has become increasingly popular, with a growing body of research supporting its use for scars and burns. Numerous methods are available for the treatment of these skin diseases, including different nonsurgical laser therapies. To date, the optimal treatment method for scars, keloids, and burn injuries of the skin has not yet been established, although it is an area of increasing clinical concern. This review provides an updated summary of the treatment of scars and burn wounds of the skin using different laser treatments, including the most recent technologies. It addresses their indications, mechanisms of action, differences, efficacies, and complications.
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http://dx.doi.org/10.1089/wound.2018.0857DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6906753PMC
April 2019

Fat grafting rescues radiation-induced joint contracture.

Stem Cells 2020 03 3;38(3):382-389. Epub 2019 Dec 3.

Hagey Laboratory for Pediatric Regenerative Medicine, Department of Surgery, Division of Plastic Surgery, Stanford University School of Medicine, Stanford, California.

The aim of this study was to explore the therapeutic effects of fat grafting on radiation-induced hind limb contracture. Radiation therapy (RT) is used to palliate and/or cure a range of malignancies but causes inevitable and progressive fibrosis of surrounding soft tissue. Pathological fibrosis may lead to painful contractures which limit movement and negatively impact quality of life. Fat grafting is able to reduce and/or reverse radiation-induced soft tissue fibrosis. We explored whether fat grafting could improve extensibility in irradiated and contracted hind limbs of mice. Right hind limbs of female 60-day-old CD-1 nude mice were irradiated. Chronic skin fibrosis and limb contracture developed. After 4 weeks, irradiated hind limbs were then injected with (a) fat enriched with stromal vascular cells (SVCs), (b) fat only, (c) saline, or (d) nothing (n = 10/group). Limb extension was measured at baseline and every 2 weeks for 12 weeks. Hind limb skin then underwent histological analysis and biomechanical strength testing. Irradiation significantly reduced limb extension but was progressively rescued by fat grafting. Fat grafting also reduced skin stiffness and reversed the radiation-induced histological changes in the skin. The greatest benefits were found in mice injected with fat enriched with SVCs. Hind limb radiation induces contracture in our mouse model which can be improved with fat grafting. Enriching fat with SVCs enhances these beneficial effects. These results underscore an attractive approach to address challenging soft tissue fibrosis in patients following RT.
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http://dx.doi.org/10.1002/stem.3115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8033730PMC
March 2020

Retrospective cohort-based comparison of intraoperative liposomal bupivacaine versus bupivacaine for donor site iliac crest analgesia during alveolar bone grafting.

J Plast Reconstr Aesthet Surg 2019 Dec 2;72(12):2056-2063. Epub 2019 Oct 2.

Hagey Laboratory for Pediatric Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, United States; Division of Plastic and Reconstructive Surgery, Stanford University Medical Center, 257 Campus Drive West, Stanford, CA 94305, United States. Electronic address:

Introduction: Bone grafting of alveolar clefts is routinely performed with cancellous bone harvested from the iliac crest. Graft site morbidity is frequently seen, with early postoperative pain being one of the most common complaints. Liposomal bupivacaine (LB) has been demonstrated to provide improvement in postoperative pain for patients undergoing bunionectomy or hemorrhoidectomy, which may translate to patients requiring iliac crest bone graft harvest.

Methods: Thirty-eight patients undergoing iliac crest bone harvest were included in the study. Twenty-one patients underwent open iliac crest bone graft harvest with administration of 0.25% bupivacaine at the hip donor site, while 17 patients received local infiltration of 1.3% liposomal bupivacaine. Patient-reported pain scores, total narcotic use, length of stay, and postoperative steps were monitored.

Results: There were no significant differences in age, weight, distribution of clefts, or choice of donor hip between the two groups. There were no significant differences in length of hospitalization stay. However, differences were noted in average postoperative pain scores at five of six time points in the first 24 h, total oral morphine equivalents administered (4.7 ± 5.3 vs. 14.3 ± 12.0), and steps at postoperative days one to three (p < 0.001, for all three days) for patients receiving 1.3% LB versus 0.25% bupivacaine, respectively.

Conclusion: Reduced pain scores and increased postoperative activity highlight the potential of LB to improve postoperative pain management in children undergoing iliac crest bone harvest for alveolar bone grafting.
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http://dx.doi.org/10.1016/j.bjps.2019.09.026DOI Listing
December 2019

Much-Needed Clarification and Guidance on Cell-Based Therapies for Musculoskeletal Disorders - Secondary Publication.

J Orthop Res 2020 03 1;38(3):483-484. Epub 2019 Oct 1.

Hagey Laboratory for Pediatric Regenerative Medicine, Department of Surgery, Plastic and Reconstructive Surgery Division, Stanford University, Stanford, CA.

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http://dx.doi.org/10.1002/jor.24486DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7169986PMC
March 2020

Should free deep inferior epigastric artery perforator flaps be considered a quality indicator in breast reconstruction?

J Plast Reconstr Aesthet Surg 2019 Dec 7;72(12):1923-1929. Epub 2019 Sep 7.

Division of Plastic and Reconstructive Surgery, Hagey Laboratory for Pediatric Regenerative Medicine, Stanford University School of Medicine, 770 Welch Road, Suite 400, Stanford, Palo Alto, CA 94304, United States. Electronic address:

Over the past several decades, technical advances in breast reconstruction have resulted in the development of flaps that are aimed at progressively decreasing abdominal wall morbidity. There is, however, ongoing controversy related to the superiority of deep inferior epigastric perforator (DIEP) flaps over muscle-sparing TRAM (MS-TRAM) flaps. Hence, the question remains unanswered as to which approach should be considered the standard of care, and more importantly, whether the rate of DIEP flap utilization should be considered a quality metric in breast reconstruction. In this review article, we examine the literature pertaining to abdominal free tissue transfer in breast reconstruction from both donor site and flap characteristics as well as the resultant complications and morbidity. The impact on the donor site remains a prevailing principle for autologous breast reconstruction; thus, must be adequately respected when classifying what is left behind following flap harvest. The most commonly used nomenclature is too simplistic. This, in turn, leads to inadequate incorporation of critical variables, such as degree of muscular preservation, fascial involvement, mesh implantation, and segmental nerve anatomy. Currently, there is insufficient evidence to support DIEP flap harvest as a quality indicator in breast reconstruction, as DIEP flap outcomes are not clearly superior when compared with MS-TRAM flaps.
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http://dx.doi.org/10.1016/j.bjps.2019.08.005DOI Listing
December 2019

Discussion: Recipient-Site Preconditioning with Deferoxamine Increases Fat-Graft Survival by Inducing VEGF and Neovascularization in a Rat Model.

Plast Reconstr Surg 2019 10;144(4):630e-631e

From the Division of Plastic and Reconstructive Surgery, Department of Surgery, Stanford University; and the Center of Plastic, Aesthetic, Hand, and Reconstructive Surgery, University Hospital Regensburg.

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http://dx.doi.org/10.1097/PRS.0000000000006037DOI Listing
October 2019

A Matched-Pair Analysis of Prepectoral with Subpectoral Breast Reconstruction: Is There a Difference in Postoperative Complication Rate?

Plast Reconstr Surg 2019 10;144(4):801-807

From the Division of Plastic and Reconstructive Surgery, Stanford University Medical Center.

Background: The development of acellular dermal matrices has revolutionized implant-based breast reconstruction. The most recent development has been the introduction of prepectoral breast reconstruction. However, concerns have been expressed related to the quality of soft-tissue coverage and infectious complications. Thus, the authors felt it prudent to perform a matched-pair analysis of clinical outcomes following prepectoral and subpectoral tissue expander placement.

Methods: A retrospective study of patients who underwent immediate breast reconstruction by means of prepectoral (group 1) and dual-plane subpectoral (group 2) tissue expander placement was performed. Patients in each group were matched for age, body mass index, history of radiotherapy, and type of acellular dermal matrix. Of note, patients in group 1 received perioperative antibiotic prophylaxis for less than 24 hours, whereas patients in group 2 received antibiotic prophylaxis for at least 1 week.

Results: A total of 80 patients (138 breast reconstructions) were included in the study (group 1, n = 40; group 2, n = 40). No difference in total postoperative complication rate (p = 0.356) and mastectomy skin necrosis rate (p = 1.0) was noted. Observed differences in major complications (p = 0.06), major infection (p = 0.09), and loss of reconstruction (p = 0.09) were not found to be significant.

Conclusion: Immediate prepectoral tissue expander insertion with anterior acellular dermal matrix coverage and less than 24 hours of antibiotic prophylaxis is safe and compares favorably to subpectoral tissue expander placement with an inferior acellular dermal matrix sling and a prolonged course of antibiotics.

Clinical Question/level Of Evidence: Therapeutic, III.
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http://dx.doi.org/10.1097/PRS.0000000000006008DOI Listing
October 2019