Fibrochondrogenic Differentiation Potential of Human Adiposederived Mesenchymal Stem Cells in a Type I Collagen-based Meniscus Scaffold with Activated Platelet-Rich Plasma Stimulation In-vitro

Introduction: Despite efforts to use scaffolds to treat meniscus tears, minimal progress has been made in facilitating meniscus regeneration and return of function. Our research objective was to develop a meniscus repair and regeneration implant by applying a resorbable scaffold in combination with cells and growth factors. We report here the results of using Platelet-Rich Plasma (PRP) as a source of growth factors to induce fibrochondrogenic differentiation of human Adipose- Derived Mesenchymal Stem Cells (hADSC) in a three-dimensional (3D) Type I collagen-based scaffold in-vitro. Methods: Scaffold Preparation: Type I collagen scaffolds were prepared following a protocol previously published. Two different densities of scaffolds, High Density (HD) and Low Density (LD), were produced for in-vitro study. hADSC and PRP Preparation. hADSCs were cultured to the fifth passage to reach the desired number for experimentation. PRP was collected from human blood and activated. Cell Culture Procedure: Effects of PRP on hADSC proliferation and differentiation into fibrochondrogenic cells were examined in four scaffold groups: LD, HD, LD+PRP and HD+PRP. hADSCs were seeded onto scaffolds (n=5) at a concentration of 2 × 106 cells/scaffold. 1% of PRP was added to the experimental media. Cellular proliferation was assessed at 1, 7, 14 and 21 days. Differentiation was measured using qRT-PCR on Days 14 and 21. qRT- PCR analysis of gene expression was completed with primers for COLLAGEN 1 and AGGRECAN. Data Analysis: ANOVAs were conducted (two-tailed tests) at the .05 significance level. Results: Cellular proliferation of hADSCs seeded on each scaffold increased over time. Similar trend was observed for cells seeded on HD scaffolds with and without PRP. hADSC showed significant increase in cellular proliferation on the LD scaffolds at Days 1 and 7. At Day 21, PRP treatment and LD scaffold had a synergistic positive effect on Type I collagen gene expression. PRP did not elevate type I collagen gene in the HD group, the HD scaffold alone had the same level of type I collagen gene expression as LD+PRP. Aggrecan expression was elevated in the presence of PRP in both the HD and LD scaffold groups, indicating enhanced fibrochondrogenic differentiation of hADSCs. Effective cell infiltration was observed across both HD and LD scaffolds with and without PRP treatment. HD scaffolds displayed larger cell clusters and more extensive cell migration over time compared to LD scaffolds. However, LD scaffolds resulted a more uniform cellular distribution than HD scaffolds. Conclusion: Our study demonstrates that PRP can play an important role in directing hADSCs towards fibrochondrogenic differentiation in Type I collagen-based scaffolds in-vitro. Additionally, our study shows that collagen scaffold density can influence the spatial distribution and cellular behavior of infiltrated cells.