Mesenchymal Stem Cells from the Retropatellar Fat Pad and Peripheral Blood Stimulate ACL Fibroblast Migration, Proliferation, and Collagen Gene Expression

Abstract

Mesenchymal stem cells (MSCs) have been of recent interest as adjuncts for ligament repair. However, the effect of these cells on the resident ligament fibroblasts has not yet been defined. In this study, we hypothesized that co-culture of MSCs and ligament fibroblasts would result in increases in the proliferative rate of the ligament fibroblasts and their expression of collagen-related genes, as well as differentiation of the MSCs down a fibroblastic pathway. In addition, we hypothesized that these effects would be dependent on the source of the MSCs. Porcine MSCs were isolated from both the retro-patellar fat pad (ADSCs) and the peripheral blood (PBMCs) and co-cultured with porcine anterior cruciate ligament (ACL) fibroblasts. Fibroblast migration, proliferation, and collagen gene expression were evaluated at time points up to 14 days. ADSCs had a greater effect on stimulating ACL-fibroblast proliferation and procollagen production, while PBMCs were more effective in stimulating ligament fibroblast migration. In addition, co-culture with the ACL fibroblasts led to significant increases in collagen gene expression for ADSCs, suggesting a differentiation of these cells down a fibroblastic pathway during the co-culture period. This was not seen for the PBMCs. Thus, the effects of MSCs on in situ ACL fibroblasts were found to be source dependent, and the choice of MSC source should take into account the different performance characteristic of each type of MSC.

Addition of Autologous Mesenchymal Stem Cells to Whole Blood for Bioenhanced ACL Repair Has No Benefit in the Porcine Model

“…Linear stiffness values of 32% of the intact ACL values in this study were comparable to earlier results that averaged between 20% and 33%. 28, 31, 40 The linear stiffness results are encouraging as this is the parameter that tissue engineers attempt to replicate as ligaments and tendons routinely operate in the range that is less than 10% of the failure load when patients perform activities of daily living. 6 …”

“…20 And as shown before, whole blood contains stem cells that have the potential to differentiate into the fibroblast cell line. 7, 8, 23, 40 …”

“…40 Two weeks ahead of the ACL surgery, animals from group ADSC had a small portion of their retropatellar fat pad from the left knee [weight (mean ± SD): 1.1 ± 0.21 g)] removed through a small medial arthrotomy. This tissue was minced, digested with collagenase (Worthington Biochemical, Lakewood Township, NJ, USA), and filtered through a cell strainer (BD Falcon, Franklin Lakes, NJ, USA).…”

“…8 In a study utilizing co-culture of ACL fibroblasts and PBSCs, PBSCs had increased collagen type I gene expression, an indicator of their potential to differentiate into the fibroblast lineage. 40 PBSCs have also been shown to enhance the anabolic effects of platelet-rich plasma on ACL fibroblasts 53 as well as stimulate the proliferation and collagen gene expression in these cells by co-culture. 40 …”

“…40 PBSCs have also been shown to enhance the anabolic effects of platelet-rich plasma on ACL fibroblasts 53 as well as stimulate the proliferation and collagen gene expression in these cells by co-culture. 40 …”