Early immunomodulatory effects of implanted human perivascular stromal cells during bone formation

Human perivascular stem/stromal cells (PSC) are a multipotent mesodermal progenitor cell population defined by their perivascular residence. PSC are most commonly derived from subcutaneous adipose tissue, and recent studies have demonstrated the high potential for clinical translation of this fluorescence activated cell sorting (FACS) derived cell population for bone tissue engineering. Specifically, purified PSC induce greater bone formation than unpurified stroma taken from the same patient sample. Here, we examined the differences in early innate immune response to human PSC or unpurified stroma (stromal vascular fraction, SVF) during the in vivo process of bone formation. Briefly, SVF or PSC from the same patient sample were implanted intramuscularly in the hindlimb of SCID mice using an osteoinductive demineralized bone matrix carrier. Histologic examination of early inflammatory infiltrates was examined by H&E and immunohistochemical staining (Ly-6G, F4/80). Results showed significantly greater neut...