Abstract:
Osteochondral explants can serve as valuable ex vivo models for investigating joint development and testing therapeutic
interventions in osteoarthritis (OA). The incorporation of synovial tissue in coculture settings more closely
reproduces the inflammatory milieu characteristic of OA joints; however, no report exists regarding the culture
media that can support such ex vivo systems. We investigated the reactivity of osteochondral explants using two
media types: Dulbecco’s modified essential medium (DMEM) and chondrogenic medium (CHONDRO).
Additionally, we tested the potential therapeutic effect of serum-free conditioned media (CM) derived from allogeneic
adipose-derived stem cells (ADSCs) in the context of OA. Osteochondral fragments with or without homologous
synovium were cultured in DMEM and CHONDRO for up to 30 days. A subset of explants received
treatment with CM. Explant reactivity was assessed by cytokine release, synovial cellularity, and osteochondral
protein content usingWestern blot and immunohistochemistry. Explants kept in DMEMdisplayed diminished levels
of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFa), together with increased Collagen II (Col II)
expression. Notably, consistent suppression of TNFa was observed following CM treatment. Conversely, the
CHONDRO-kept samples exhibited an increased prevalence of chondrocyte clusters; heightened Perlecan presence
as well as IL-1b levels in response to CMtreatment and synovial tissue-dependent fluctuations in Col II levels.
Remarkably, significantly increased b-galactosidase levels could be detected in osteochondral tissues treated with
CM, regardless of the culturemedia type. In the experimental conditions created, DMEMprovided a neutral milieu
and was less prone to confounding experimental outcomes, rendering it suitable for evaluating potential therapies.
CHONDRO apparently increased chondrocyte clusters and facilitated extracellular matrix synthesis; however, its
usage requires caution due to potential interference with experimental readouts. CM could exert an antisenescence
effect, an effect that warrants further investigation.
