Differential effect of platelet-rich plasma and fetal calf serum on bone marrow-derived human mesenchymal stromal cells expanded in vitro.

Mesenchymal stromal cells (MSCs) derived from various sources have great potential for use in cell-based therapies. Since the proportion of primary MSCs contained in bone marrow or adipose tissue is low, plastic adherence and in vitro expansion are necessary to expand MSCs prior to clinical application. Human platelet-rich plasma has been introduced as an alternative serum source but functional differences have so far not been described. Here we cultured MSCs derived from human bone marrow in medium supplemented with either 10% fetal calf serum (FCS) or 5% and 10% platelet-rich plasma (PRP) until the first or second passage. Parameters under investigation were cell yield, clonogenicity, phenotype as well as migratory and differentiation potential. In addition, the secretion of SDF-1α and the induced migration of CD34(+) haematopoietic stem cells (HSCs) were investigated with regard to the different serum source. The use of PRP resulted in a significantly higher expansion rate and yield at passages 0 and 1. In addition, the level of secreted SDF-1α was significantly increased in the supernatant of MSCs cultured with FCS instead of human PRP. Consistent with this, the migration capacity of MSCs cultured with 10% FCS as well as their capability to induce the migration of CD34(+) haematopoietic progenitors in a transwell assay was higher. Our results demonstrate that human PRP can be seen as an alternative serum source to FCS for MSC cultivation. However, the requirements of the specific clinical application must be carefully considered before the respective serum source is selected.

Cancellous bone allograft seeded with human mesenchymal stromal cells: a potential good manufacturing practice-grade tool for the regeneration of bone defects.

BACKGROUND AIMS: Combining autologous bone precursor cells with cancellous bone allograft (CBA) offers an appealing strategy for skeletal regeneration. In this context, multipotent mesenchymal stromal cells (MSC) provide an excellent cell source because they are readily harvested from donors, expanded and differentiated in vitro. The aim of this study was to evaluate the proliferation, morphology, osteogenic differentiation and stem cell-related gene expression during static long-term ex vivo cultivation using human MSC and CBA under good manufacturing practice (GMP)-conforming conditions. METHODS: MSC were isolated from healthy donors (n = 5) and cultivated on peracetic acid-sterilized CBA in the presence of 10% human platelet-rich plasma without osteogenic supplements. Total protein content, cell-specific alkaline phosphatase (ALP) activity and osteogenic marker gene expression levels were assessed. Stem cell-related gene expression was compared with MSC monolayer cultivation using microarray analysis. Furthermore, cellular distribution and morphology within the porous CBA were visualized by histology and scanning electron microscopy. RESULTS: Effective adhesion, spreading, proliferation and intercellular contact of human MSC within the pores of CBA were observed during the study (< or = 42 days). Cell-specific ALP activity peaked after 3 weeks of cultivation. Gene expression of early, intermediate and late osteogenic marker genes was detectable during long-term cultivation. Microarray-based annotation and biologic interaction network data analysis indicated that expression levels of genes encoding crucial differentiation-regulating proteins and extracellular matrix components involved in the process of osteogenesis were induced in CBA-cultivated MSC. CONCLUSIONS: MSC-vitalized CBA offers an attractive GMP-grade bone-filling material. Further research is warranted to evaluate its bone-healing potential in vivo.