Viability and functionality of mesenchymal stromal cells loaded on collagen microspheres and incorporated into plasma clots for orthopaedic application: Effect of storage conditions.

BACKGROUND: There is evidence showing that human mesenchymal stromal cells (MSC) seeded on collagen microspheres (CM) and incorporated into platelet rich plasma (PRP) clots induce bone formation. For clinical trials it is very important to establish standardization of storage and shipment conditions to ensure the viability and functionality of cellular products. We investigate the effect of storage temperature and time on the viability and functionality of human MSC seeded on CM and included into PRP clots for using in the further clinical application for bone regeneration.

METHODS: MSC/CM/PRP clots were stored at room temperature (RT), 4 °C and 37 °C for 12 h, 24 h and 48 h. At each period of time, MSC were evaluated for their viability and functionality.

RESULTS: MSC from MSC/CM/PRP clots maintained at RT and 37 °C for 24 h showed a high viability (90%) and maintained their capacity of proliferation, migration and osteogenic differentiation. In contrast, MSC/CM/PRP maintained to 4 °C showed a significant reduction in their viability and migration capacity. MSC from MSC/CM/PRP clots maintained at RT for 24 h induce osteogenesis in the subcutaneous tissues of mice, after four months of transplantation.

DISCUSSION: Our results show that MSC incorporated into CM/PRP clots and maintained at RT can be utilized in bone regeneration protocols during the first 24 h after their processing.