Native-Osteoarthritic Joint Resident Stem and Progenitor Cells for Cartilage Cell-Based Therapies: A Quantitative Comparison With Respect to Concentration and Biological Performance.

Background: Cell-based therapy for cartilage repair is a promising approach and is becoming an established technique. Yet, there is no consensus on the optimal cell source.
Purpose: To provide a donor-matched quantitative comparison of the connective tissue progenitors (CTPs) derived from cartilage (Outerbridge grade 1-3 [G1-2-3]), bone marrow aspirate concentrate (BMC), infrapatellar fat pad (IPFP), synovium, and periosteum with respect to (1) cell concentration ([Cell], cells/mL), (2) CTP prevalence (P _CTP , colonies per million cells), and (3) biological performance based on in vitro proliferation potential (cells per colony) colony density, and differentiation potential (expression of negatively charged extracellular matrix: glycosaminoglycan-rich extra cellular matrix [GAG-ECM]).
Study Design: Descriptive laboratory study.
Methods: Tissues were obtained from 10 patients undergoing total knee arthroplasty (mean age, 59 years; women, n = 6). Automated quantitative colony-forming unit analysis was used to compare [Cell], P _CTP , and CTP biological performance across tissue sources.
Results: [Cell] was highest in grade 3 cartilage ( P = .002) and BMC ( P = .001). Median P _CTP was highest in IPFP ( P = .001), synovium ( P = .003), and G1-2 cartilage ( P = .02). Proliferation was highest in synovium-derived CTPs ( P < .001). Median colony density was highest in G1-2-3 ( P < .001). Median GAG-ECM was highest in G1-2-3 ( P < .001). Within each patient, CTPs derived from all tissues were highly heterogeneous in biological performance as determined by cells per colony, density, and GAG-ECM.
Conclusion: Tissue sources differ in [Cell], P _CTP , and biological attributes. The data presented in this study suggest that cartilage (G1-2-3) is the preferred tissue source for cartilage repair based on P _CTP and GAG-ECM, followed by synovium, IPFP, BMC, and periosteum. However, due to the heterogeneous mixture of CTPs within each tissue source, there exists a subset of CTPs with biological performance similar to G1-2-3 cartilage, particularly in synovium and IPFP. Performance-based clonal selection and expansion of preferred CTPs and their progeny will potentially lead to improved cell population with predictive future.
Clinical Relevance: Optimal tissue regeneration strategies will require informed decisions regarding which of the available tissue sources to use. Optimizing cell sourcing in any tissue may require separation of CTPs with preferred attributes from those with less desirable attributes. The heterogeneity manifest in the early stage of colony formation represents an opportunity for performance-based clone selection for clinical cell processing and manufacturing.