Cellular responses in acetabular labral reconstruction: effects of strain level on labral, tibialis tendon, and meniscal cells <i>in vitro</i>.

Abstract

While the clinical outcomes of acetabular labral repair and reconstruction have been reported, comparative cellular responses between common allografts to clinically relevant load are less clear. This study aims to compare acetabular labrum (LAB), anterior tibialis tendon (TEN), and knee meniscus (MEN) cellular responses to biaxial tensile strain during <i>in vitro</i> culture. LAB, TEN, and MEN tissues were recovered from skeletally mature research hounds (<i>n</i> = 5). Primary LAB, TEN, and MEN fibroblast cell cultures were established. Using a bioreactor, cells were loaded at 0%, 4%, or 10% biaxial tensile strain for 5 days. RNA was extracted and reverse transcription-polymerase chain reaction (RT-PCR) was used to determine relative gene expression levels. Cells were then tested for various stress-induced biomarkers. Statistical analysis determined significance between groups for relative gene expression levels and biomarker concentrations. LAB in the 0% strain group had more viable cells compared to the 4% and 10% strain groups, and MEN fibroblasts in the 4% strain group had more viable cells compared to the 10% strain group. LAB and MEN were associated with higher concentrations of MMP-3 in the 10% strain compared to the 0% strain group. The characterization of acetabular labrum cellular responses to clinically relevant loads of force more closely matches those of meniscal allograft tissue than tibialis anterior allograft tissue. This has potential implications for labral reconstruction, as meniscal allograft tissues may be more suited than tibialis anterior tissues to withstand compressive forces necessary for stabilization and chondroprotection within the hip.