Table 2.

A synthesis of the main issues in MSC efficacy in the treatment of OA and limitations to adequate assessment through clinical trials

Key factors for stem cell efficacy in OA

Key factors limiting stem cell efficacy and clinical trial interpretation of MSC use in OA

• Age (younger patients typically display better outcomes) • Gender (males typically better outcomes compared to female counterparts) • BMI (lower BMI is associated with better outcomes) • Lesion or defect size (better repair associated with smaller lesion size) • Stage of OA (early OA, mild to moderate OA correlated with better outcomes)

• Significant variation in MSC source • Significant variation in MSC preparation protocols • Variation in MSC Delivery • Significant variation in the number of different co-interventions with MSCs  Micro-fracture, sub-chondral drilling, debridement, and platelet rich plasma  Less common—hyaluronic acid, albumin and serum, osteophyte removal, and surgical interventions (ACL repair and high tibial osteotomy)