Mesenchymal Stromal Cells from the Maternal Segment of Human Umbilical Cord is Ideal for Bone Regeneration in Allogenic Setting

Umbilical cord (UC) is a discarded product from the operating theatre and a ready source of mesenchymal stromal cells (MSCs). MSCs from UC express both embryonic and adult mesenchymal stem cell markers and are known to be hypoimmunogenic and non-tumorigenic and thus suitable for allogeneic cell transplantation. Our study aimed to determine the degree of immunotolerance and bone-forming capacity of osteodifferentiated human Wharton's jelly-derived mesenchymal stromal cells (hWJ-MSCs) from different segments of UC in an allogenic setting. UCs were obtained from healthy donors delivering a full-term infant by elective Caesarean section. hWJ-MSCs were isolated from 3 cm length segment from the maternal and foetal ends of UCs. Three-dimensional fibrin constructs were formed and implanted intramuscularly into immunocompetent mice. The mice were implanted with 1) fibrin construct with maternal hWJ-MSCs, 2) fibrin construct with foetal hWJ-MSCs, or 3) fibrin without cells; the control group received sham surgery. After 1 month, the lymphoid organs were analysed to determine the degree of immune rejection and bone constructs were analysed to determine the amount of bone formed. A pronounced immune reaction was noted in the fibrin group. The maternal segment constructs demonstrated greater osteogenesis than the foetal segment constructs. Both maternal and foetal segment constructs caused minimal immune reaction and thus appear to be safe for allogeneic bone transplant. The suppression of inflammation may be a result of increased anti-inflammatory cytokine production mediated by the hWJ-MSC. In summary, this study demonstrates the feasibility of using bone constructs derived from hWJ-MSCs in an allogenic setting.