Adipose-Derived Stromal/Stem Cell Culture: Effects of Different Concentrations of Human Platelet Lysate in Media

Abstract

Adipose-derived stromal/stem cells (ASCs) are being tested as a possible treatment for a wide range of diseases to exploit the immunomodulatory and regenerative potential demonstrated in vitro. Pooled human platelet lysate (pHPL) has replaced fetal bovine serum (FBS) as the preferred growth supplement because of its xeno-free origin and improved cell proliferation. Much has been done toward reducing the concentration of pHPL required when expanding ASCs. However, little is known on how increasing the concentration of pHPL affects ASC potency, which could lead to changes with possible beneficial applications. This study investigated the effect of 5, 10, or 20% pHPL in culture media on ASC proliferation and phenotypic marker expression, including chemokine receptors CXCR2, CXCR3, CXCR4, and VLA-4. Adipogenic and osteogenic properties, as well as immunosuppressive properties, including the ability to induce indoleamine-pyrrole 2,3-dioxygenase 1 (IDO1) and suppress T cell proliferation, were also examined. We observed a significant increase in cell yield (approximately 2-fold) and a corresponding reduction in population doubling time and cell volume when doubling the concentration of pHPL in the growth media. ASCs maintained expression of phenotypic surface markers CD73, CD90, and CD105 and were negative for CD45 and CD31. The ability to induce IDO1 and suppress T cell proliferation was observed as well. Adipogenesis and osteogenesis, however, seem to be increased at higher concentrations of pHPL (20% > 10% > 5%), while expression of chemokine receptors CXCR2 and CXCR3 was lower. In conclusion, increasing the pHPL concentration to 20% could be used to optimize culture conditions when producing cells for clinical treatments and may even be used to enhance beneficial ASC properties depending on the desired therapeutic effect.