Publications by authors named "Mekala-Subba Rao"

7 Publications

  • Page 1 of 1

Bone marrow-derived myeloid progenitors in the leptomeninges of adult mice.

Stem Cells 2021 02 11;39(2):227-239. Epub 2020 Dec 11.

Institute of Anatomy and Cell Biology, Julius Maximilian University of Würzburg, Würzburg, Germany.

Although the bone marrow contains most hematopoietic activity during adulthood, hematopoietic stem and progenitor cells can be recovered from various extramedullary sites. Cells with hematopoietic progenitor properties have even been reported in the adult brain under steady-state conditions, but their nature and localization remain insufficiently defined. Here, we describe a heterogeneous population of myeloid progenitors in the leptomeninges of adult C57BL/6 mice. This cell pool included common myeloid, granulocyte/macrophage, and megakaryocyte/erythrocyte progenitors. Accordingly, it gave rise to all major myelo-erythroid lineages in clonogenic culture assays. Brain-associated progenitors persisted after tissue perfusion and were partially inaccessible to intravenous antibodies, suggesting their localization behind continuous blood vessel endothelium such as the blood-arachnoid barrier. Flt3 lineage tracing and bone marrow transplantation showed that the precursors were derived from adult hematopoietic stem cells and were most likely continuously replaced via cell trafficking. Importantly, their occurrence was tied to the immunologic state of the central nervous system (CNS) and was diminished in the context of neuroinflammation and ischemic stroke. Our findings confirm the presence of myeloid progenitors at the meningeal border of the brain and lay the foundation to unravel their possible functions in CNS surveillance and local immune cell production.
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http://dx.doi.org/10.1002/stem.3311DOI Listing
February 2021

Generation of Cardiomyocytes From Vascular Adventitia-Resident Stem Cells.

Circ Res 2018 08;123(6):686-699

From the Institute of Anatomy and Cell Biology II (S.R.M., P.W., J.B., O.S., N.W., L.R., K.L., G.E., C.K.K., F.E., V.P., S.K., S.E.).

Rationale: Regeneration of lost cardiomyocytes is a fundamental unresolved problem leading to heart failure. Despite several strategies developed from intensive studies performed in the past decades, endogenous regeneration of heart tissue is still limited and presents a big challenge that needs to be overcome to serve as a successful therapeutic option for myocardial infarction.

Objective: One of the essential prerequisites for cardiac regeneration is the identification of endogenous cardiomyocyte progenitors and their niche that can be targeted by new therapeutic approaches. In this context, we hypothesized that the vascular wall, which was shown to harbor different types of stem and progenitor cells, might serve as a source for cardiac progenitors.

Methods And Results: We describe generation of spontaneously beating mouse aortic wall-derived cardiomyocytes without any genetic manipulation. Using aortic wall-derived cells (AoCs) of WT (wild type), αMHC (α-myosin heavy chain), and Flk1 (fetal liver kinase 1)-reporter mice and magnetic bead-associated cell sorting sorting of Flk1 AoCs from GFP (green fluorescent protein) mice, we identified Flk1CD (cluster of differentiation) 34Sca-1 (stem cell antigen-1)-CD44 AoCs as the population that gives rise to aortic wall-derived cardiomyocytes. This AoC subpopulation delivered also endothelial cells and macrophages with a particular accumulation within the aortic wall-derived cardiomyocyte containing colonies. In vivo, cardiomyocyte differentiation capacity was studied by implantation of fluorescently labeled AoCs into chick embryonic heart. These cells acquired cardiomyocyte-like phenotype as shown by αSRA (α-sarcomeric actinin) expression. Furthermore, coronary adventitial Flk1 and CD34 cells proliferated, migrated into the myocardium after mouse myocardial infarction, and expressed Isl-1 (insulin gene enhancer protein-1) indicative of cardiovascular progenitor potential.

Conclusions: Our data suggest Flk1CD34 vascular adventitia-resident stem cells, including those of coronary adventitia, as a novel endogenous source for generating cardiomyocytes. This process is essentially supported by endothelial cells and macrophages. In summary, the therapeutic manipulation of coronary adventitia-resident cardiac stem and their supportive cells may open new avenues for promoting cardiac regeneration and repair after myocardial infarction and for preventing heart failure.
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http://dx.doi.org/10.1161/CIRCRESAHA.117.312526DOI Listing
August 2018

The vascular adventitia: An endogenous, omnipresent source of stem cells in the body.

Pharmacol Ther 2017 03 3;171:13-29. Epub 2016 Aug 3.

Institute of Anatomy and Cell Biology, University of Würzburg, Germany. Electronic address:

Until a decade ago it was believed that the wall of adult blood vessels exclusively contains terminally differentiated cell types. A paradigm shift was unavoidable since studies from different groups convincingly showed the presence of vascular wall-resident stem and progenitor cells (VW-SCs) which were identified to particularly reside in the sub-endothelial space and the so-called adventitial "vasculogenic zone". Data published during the last decade uncloaked the fact that VW-SCs have the capacity to differentiate into both vascular and non-vascular cell types. Up to date, little is known about the full capacity of VW-SCs, the exact composition of their endogenous niche and the mechanisms that govern their self-renewal, activation and differentiation. The aim of this review is to provide an overview about the current knowledge on VW-SCs and to highlight the impact of this endogenous niche on health and disease. In addition, we will discuss strategies how these adult stem cells could be manipulated in order to activate and expand them, ideally within their niche at sites of tissue damage and subsequently differentiate them into a desired cell type, e.g. an endothelial cell, a macrophage or a muscle cell. This would pave the way towards new pharmacological strategies for endogenous tissue repair and regeneration.
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http://dx.doi.org/10.1016/j.pharmthera.2016.07.017DOI Listing
March 2017

Thinking outside the liver: induced pluripotent stem cells for hepatic applications.

World J Gastroenterol 2013 Jun;19(22):3385-96

Institute of Basic Sciences and Translational Research, Asian Healthcare Foundation, Asian Institute of Gastroenterology, Hyderabad 500082, India.

The discovery of induced pluripotent stem cells (iPSCs) unraveled a mystery in stem cell research, after identification of four re-programming factors for generating pluripotent stem cells without the need of embryos. This breakthrough in generating iPSCs from somatic cells has overcome the ethical issues and immune rejection involved in the use of human embryonic stem cells. Hence, iPSCs form a great potential source for developing disease models, drug toxicity screening and cell-based therapies. These cells have the potential to differentiate into desired cell types, including hepatocytes, under in vitro as well as under in vivo conditions given the proper microenvironment. iPSC-derived hepatocytes could be useful as an unlimited source, which can be utilized in disease modeling, drug toxicity testing and producing autologous cell therapies that would avoid immune rejection and enable correction of gene defects prior to cell transplantation. In this review, we discuss the induction methods, role of reprogramming factors, and characterization of iPSCs, along with hepatocyte differentiation from iPSCs and potential applications. Further, we discuss the location and detection of liver stem cells and their role in liver regeneration. Although tumor formation and genetic mutations are a cause of concern, iPSCs still form a promising source for clinical applications.
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http://dx.doi.org/10.3748/wjg.v19.i22.3385DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3683676PMC
June 2013

Derivation, characterization and retinal differentiation of induced pluripotent stem cells.

J Biosci 2013 Mar;38(1):123-34

Sudhakar and Sreekanth Ravi Stem Cell Biology Laboratory, Prof Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, C-TRACER, L.V. Prasad Eye Institute, Hyderabad, India.

Millions of people world over suffer visual disability due to retinal dystrophies which can be age-related or a genetic disorder resulting in gradual degeneration of the retinal pigmented epithelial (RPE) cells and photoreceptors. Therefore, cell replacement therapy offers a great promise in treating such diseases. Since the adult retina does not harbour any stem cells, alternative stem cell sources like the embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) offer a great promise for generating different cell types of the retina. Here, we report the derivation of four iPSC lines from mouse embryonic fibroblasts (MEFs) using a cocktail of recombinant retroviruses carrying the genes for Oct4, Sox2, Klf4 and cMyc. The iPS clone MEF-4F3 was further characterized for stemness marker expression and stable reprogramming by immunocytochemistry, FACS and RT-PCR analysis. Methylation analysis of the nanog promoter confirmed the reprogrammed epigenetic state. Pluripotency was confirmed by embryoid body (EB) formation and lineage-specific marker expression. Also, upon retinal differentiation, patches of pigmented cells with typical cobble-stone phenotype similar to RPE cells are generated within 6 weeks and they expressed ZO-1 (tight junction protein), RPE65 and bestrophin (mature RPE markers) and showed phagocytic activity by the uptake of fluorescent latex beads.
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http://dx.doi.org/10.1007/s12038-012-9296-1DOI Listing
March 2013

Identification of circulating CD90 CD73 cells in cirrhosis of liver.

World J Stem Cells 2011 Jul;3(7):63-9

Mitnala Sasikala, Pugazhelthi Surya, Gaddipati Radhika, Pondugala Pavan Kumar, Mekala Subba Rao, Rathindra Mohan Mukherjee, Institute of Basic Sciences and Translational Research, Asian Health Care Foundation, Hyderabad 500082, India.

Aim: To identify circulating CD90(+) CD73(+) CD45(-) cells and evaluate their in vitro proliferating abilities.

Methods: Patients with cirrhosis (n = 43), and healthy volunteers (n = 40) were recruited to the study. Mononuclear cells were isolated and cultured from the peripheral blood of controls and cirrhosis patients. Fibroblast-like cells that appeared in cultures were analyzed for morphological features, enumerated by flow cytometry and confirmed by immunocytochemistry (ICC). Colony forming efficiency (CFE) of these cells was assessed and expressed as a percentage.

Results: In comparison to healthy volunteers, cells obtained from cirrhotic patients showed a significant increase (P < 0.001) in the percentage of CD90(+) CD73(+) CD45(-) cells in culture. Cultured cells also showed 10 fold increases in CFE. Flow cytometry and ICC confirmed that the proliferating cells expressed CD90(+) CD73(+) in the cultures from cirrhosis patients.

Conclusion: These results indicate the presence of circulating CD90(+) CD73(+) CD45(-) cells in patients with liver cirrhosis that have the potential to proliferate at a higher rate.
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http://dx.doi.org/10.4252/wjsc.v3.i7.63DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3158899PMC
July 2011

Characterization of hepatic progenitors from human fetal liver during second trimester.

World J Gastroenterol 2008 Oct;14(37):5730-7

Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India.

Aim: To enrich hepatic progenitors using epithelial cell adhesion molecule (EpCAM) as a marker from human fetal liver and investigate the expression of human leukocyte antigen (HLA) and their markers associated with hepatic progenitor cells.

Methods: EpCAM +ve cells were isolated using magnetic cell sorting (MACS) from human fetuses (n = 10) at 15-25 wk gestation. Expression of markers for hepatic progenitors such as albumin, alpha-fetoprotein (AFP), CD29 (integrin beta1), CD49f (integrin alpha6) and CD90 (Thy 1) was studied by using flow cytometry, immunocytochemistry and RT-PCR; HLA class I (A, B, C) and class II (DR) expression was studied by flow cytometry only.

Results: FACS analysis indicated that EpCAM +ve cells were positive for CD29, CD49f, CD90, CD34, HLA class I, albumin and AFP but negative for HLA class II (DR) and CD45. RT PCR showed that EpCAM +ve cells expressed liver epithelial markers (CK18), biliary specific marker (CK19) and hepatic markers (albumin, AFP). On immunocytochemical staining, EpCAM +ve cells were shown positive signals for CK18 and albumin.

Conclusion: Our study suggests that these EpCAM +ve cells can be used as hepatic progenitors for cell transplantation with a minimum risk of alloreactivity and these cells may serve as a potential source for enrichment of hepatic progenitor.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2748210PMC
http://dx.doi.org/10.3748/wjg.14.5730DOI Listing
October 2008
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