Platelet Rich Plasma in Xeno-Free Stem Cell Culture: The Impact of Platelet Count and Processing Method

Background: Stem cell culture for regenerative medicine needs platelet rich plasma (PRP) as fetal bovine/calf serum (FBS/FCS) substitute. However, the various studies used various protocols in preparing and processing the PRP. This study aimed to compare and conclude the most effective and efficient protocol. Methods: we searched in vitro studies that used human PRP as FBS/FCS substitute to culture human cells, and compared the various available protocols to identify the easiest and effective protocols for the preparation of PRP and the release of the growth factors (GFs) to support the highest cell growth in stem cell culture. Results: ten studies fulfilled the selection criteria and were included in the analysis. Discussion: Almost all studies on bone marrow mesenchymal stem cell (BM-MSC) and adipose stem cell (AT-SC) showed that platelet lysate and/or activated platelet releasate were superior or at least the same as either FBS or FCS, except for one study that got different results on human AT-SC. Several studies showed that either 5% activated PRP (aPRP) or platelet lysate (PL) was sufficient to support cell growth, or even better when they were compared to 10% FBS, while higher concentrations were counterproductive. However, some studies showed that 10% aPRP or PL was needed. The difference between studies was due to the difference in either the PRP preparation from blood and in the PRP processing to release the GFs, which yield various GF concentrations. Conclusion: In conclusion, studies are needed to reveal the optimal final platelet counts for the various PRP processing methods for various kinds of cells. The easiest PRP processing is freezing to -20°C followed by thawing, or thrombin activation using a final concentration of 100U/mL.