Human Alternatives to Fetal Bovine Serum for the Expansion of Mesenchymal Stromal Cells from Bone Marrow

Alternative sources of adult stem cells: human amniotic membrane

Human amniotic membrane is a highly promising cell source for tissue engineering. The cells thereof, human amniotic epithelial cells (hAEC) and human amniotic mesenchymal stromal cells (hAMSC), may be immunoprivileged, they represent an early developmental status, and their application is ethically uncontroversial. Cell banking strategies may use freshly isolated cells or involve in vitro expansion to increase cell numbers. Therefore, we have thoroughly characterized the effect of in vitro cultivation on both phenotype and differentiation potential of hAEC. Moreover, we present different strategies to improve expansion including replacement of animal-derived supplements by human platelet products or the introduction of the catalytic subunit of human telomerase to extend the in vitro lifespan of amniotic cells. Characterization of the resulting cultures includes phenotype, growth characteristics, and differentiation potential, as well as immunogenic and immunomodulatory properties.

Preparation of pooled human platelet lysate (pHPL) as an efficient supplement for animal serum-free human stem cell cultures

Platelet derived growth factors have been shown to stimulate cell proliferation efficiently in vivo(1,2) and in vitro. This effect has been reported for mesenchymal stromal cells (MSCs), fibroblasts and endothelial colony-forming cells with platelets activated by thrombin(3-5) or lysed by freeze/thaw cycles(6-14) before the platelet releasate is added to the cell culture medium. The trophic effect of platelet derived growth factors has already been tested in several trials for tissue engineering and regenerative therapy.(1,15-17) Varying efficiency is considered to be at least in part due to individually divergent concentrations of growth factors(18,19) and a current lack of standardized protocols for platelet preparation.(15,16) This protocol presents a practicable procedure to generate a pool of human platelet lysate (pHPL) derived from routinely produced platelet rich plasma (PRP) of forty to fifty single blood donations. By several freeze/thaw cycles the platelet membranes are damaged and growth factors are efficiently released into the plasma. Finally, the platelet fragments are removed by centrifugation to avoid extensive aggregate formation and deplete potential antigens. The implementation of pHPL into standard culture protocols represents a promising tool for further development of cell therapeutics propagated in an animal protein-free system.