Quantification and Qualification of Stem Cells From Blood After Mobilization With Filgrastim, and Concentration Using a Platelet-Rich Plasma System

Purpose: To determine the cellular composition of a product created with peripheral blood harvested after systemic mobilization with filgrastim and processed with one point-of-care blood concentrating system, i.e., a platelet-rich plasma (PRP) system. The second purpose was to compare mobilized platelet-rich plasma (M-PRP) with a concentrated bone marrow aspirate (cBMA) and a PRP created from the same subjects with the same PRP system.

Methods: Ten healthy volunteer subjects were recruited for collection and analysis of 3 tissue sources: non-treated peripheral blood, bone marrow aspirate, and filgrastim-mobilized peripheral blood, involving 4 doses of weight-based filgrastim. One point-of-care blood and bone marrow concentrating system was used to create 3 products: PRP, cBMA, and M-PRP. Automated hematologic analysis was performed on all products to quantify total red blood cells, white blood cells (WBCs), monocyte, platelet, and hematopoietic progenitor cell (HPC) concentrations. Flow cytometry was used to determine hematopoietic and mesenchymal progenitor cell populations. Lastly, concentrates were cultured and fibroblast colony-forming units (CFU-F) and morphology of adherent cells were evaluated.

Results: M-PRP contained a greater concentration of WBC (mean difference = 53.2 k/μL; P < .0001), monocytes (mean difference = 8.3 k/μL; P = .002), and a trend toward a greater concentration of HPC (mean difference = 200.5 /μL; P = .060) when compared with PRP. M-PRP contained a greater concentration of monocytes (mean difference = 5.5 k/μL; P = .017) and a trend toward a greater concentration of platelets (mean difference = 348 k/μL; P = .051) and HPC (mean difference = 193.4 /μL; P = .068) when compared with cBMA. M-PRP had a similar concentration of platelets to PRP (mean difference = 110 k/μL; P = .051) and PRP had a greater concentration than cBMA (mean difference = 458 k/μL; P = .003). cBMA remained the only product capable of producing CFU-Fs (446 ± 247 /mL) as neither the M-PRP nor PRP produced CFU-Fs. M-PRP produced colonies consistent with WBC.

Conclusions: M-PRP, produced with filgrastim mobilized blood and a proprietary PRP system, contained more total WBCs, monocytes, platelets, and HPCs than cBMA and more WBCs, monocytes, and HPCs than PRP.

Clinical relevance: Filgrastim mobilized PRP may be an alternative to cBMA for use as a point-of-care product for orthopaedic treatments.