Publications by authors named "Johanna Holmbom"

4 Publications

  • Page 1 of 1

Fate of bone marrow-derived stromal cells after intraperitoneal infusion or implantation into femoral bone defects in the host animal.

J Tissue Eng 2010 Aug 1;2010:345806. Epub 2010 Aug 1.

Department of Medical Biochemistry and Genetics, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.

The fate of intraperitoneally injected or implanted male rat bone marrow-derived stromal cells inside female sibling host animals was traced using Y-chromosome-sensitive PCR. When injected intraperitoneally, Y-chromosome-positive cells were found in all studied organs: heart muscle, lung, thymus, liver, spleen, kidney, skin, and femoral bone marrow with a few exceptions regardless of whether they had gone through osteogenic differentiation or not. In the implant experiments, expanded donor cells were seeded on poly(lactide-co-glycolide) scaffolds and grown under three different conditions (no additives, in osteogenic media for one or two weeks) prior to implantation into corticomedullar femoral defects. Although the impact of osteogenic in vitro cell differentiation on cell migration was more obvious in the implantation experiments than in the intraperitoneal experiments, the donor cells stay alive when injected intraperitoneally or grown in an implant and migrate inside the host. However, when the implants contained bioactive glass, no signs of Y-chromosomal DNA were observed in all studied organs including the implants indicating that the cells had been eliminated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4061/2010/345806DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3042670PMC
August 2010

Hydroxyapatite coating of cellulose sponge does not improve its osteogenic potency in rat bone.

Acta Biomater 2005 Sep 15;1(5):535-44. Epub 2005 Jul 15.

Department of Medical Biochemistry and Molecular Biology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland.

Regenerated cellulose sponges were coated biomimetically with hydroxyapatite to increase their osteogenic properties. Induction of apatite precipitation was carried out with bioactive glass in simulated body fluid (SBF) for 24 h and the final coating was carried out in 1.5 x concentrated SBF for 14 days. Biomimetically mineralized and non-mineralized sponges were then implanted into standard size femoral cortical defects of rats, and the invasion of bone into the implant was followed up to one year. The apatite coating did not improve the osteoconductive property of cellulose in this rat cortical defect model. In fact, it generated a strong and highly cellular inflammatory reaction and less osteoid tissue. The biomimetic implants contained more immunodetectable TGFbeta1 (a strong stimulator of fibroblast activity) than untreated implants, and also bound more TGFbeta1 in vitro, which could, at least in part, explain the fibrotic invasion of biomimetically mineralized sponges.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.actbio.2005.05.003DOI Listing
September 2005

Intact surface of bioactive glass S53P4 is resistant to osteoclastic activity.

J Biomed Mater Res A 2006 Apr;77(1):67-74

Department of Medical Biochemistry and Molecular Biology, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, FIN 20520 Turku, Finland.

Bioactive glass reacts with body fluids and is gradually dissolved in tissues and in cell cultures. We investigated whether osteoclasts contribute to this process, by culturing newborn rat bone-marrow cells containing osteoclasts on polished bioactive glass plates (glass S53P4). The cultures were inspected at days 1-5 and stained for alkaline phosphatase (ALP) to demonstrate osteoblasts and for tartrate resistant acid phosphatase (TRAP) to visualize osteoclasts. Nonosteoclastic cells proliferated several-fold both on bioactive glass and on plastic, whereas osteoclasts and their precursors matured into multicellular giant cells and degenerated. Most cells on bioactive glass became ALP-positive, whereas on plastic the majority of cells remained ALP-negative. Osteoclasts survived on bioactive glass for 4-5 days, whereas on plastic they degenerated and disappeared after 3 days. Condensed nuclei indicating apoptosis were detected both in degenerating osteoclasts and osteoblasts. The surface of the bioactive glass reacted rapidly forming rounded pits, erosions, and cracks within 24 h in areas occupied by osteoblasts. Light microscopy and scanning electron micrographs demonstrated, however, a smooth surface below the cytoplasm of osteoclasts. This indicates that when applied on an intact bioactive glass surface, osteoclasts were unable to dissolve the glass material within this culture period.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jbm.a.30600DOI Listing
April 2006

Long-term evaluation of porous poly(epsilon-caprolactone-co-L-lactide) as a bone-filling material.

J Biomed Mater Res A 2005 Nov;75(2):308-15

Institute of Biomedicine, Department of Medical Biochemistry and Molecular Biology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland.

Porous poly(epsilon-caprolactone-co-L-lactide) (P(CL-co-LA, wt % ca. 5/95) sponges were prepared, coated biomimetically with CaP/apatite, and implanted with noncoated control sponges into rat femur cortical defects and dorsal subcutaneous space. The implants were inspected histologically at 2, 4, and 33 weeks after the operation. All implants were filled with fibrovascular tissue within 4 weeks. The femur implants were partially ossified with compact bone, which in the CaP-coated sponges was less mature and more fragmented. Approximately equal amounts of bone were observed in both types of implants. The polymer induced a mild inflammatory reaction with foreign body giant cells but no accumulation of fluid. Degradation of the polymer was slow; most of it was found intact at 33 weeks in histological samples. Nondegraded polymer seems to prevent complete ossification. Cultured osteoblasts proliferated well on apatite-coated material, whereas only a few cells were seen on noncoated material. Thus CaP/apatite coating helped the attachment of osteoblasts in cell cultures but did not offer any advantage in bone formation over noncoated material in vivo. We conclude that a shorter degradation time of P(CL-co-LA) is needed to create an optimal implant. Furthermore, in vivo experiments seem to be necessary for the estimation of osteopromotive properties of a biomaterial.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jbm.a.30418DOI Listing
November 2005