Probes for TGF-β

Abstract

BACKGROUND:

Low back pain is one of the most common ailments in western countries afflicting more than 80% of the population and the main cause is considered to be degeneration of intervertebral discs (IVDs). IL-1β is a vital inflammatory cytokine found in abundance in degenerated disc environment whereas BMP-3 is believed to promote chondrogenesis through TGF-β pathway.

AIM:

The aim was to study the effects of BMP-3, IL-1β and combination (pre-treatment with IL-1β) on hMSCs encapsulated in PuraMatrix™ hydrogel (Phg) especially in the absence of TGF-β in order to investigate the proliferation, and differentiation ability of hMSCs over 28 days period.

METHOD:

100µL of hMSCs cell suspension was encapsulated between two layers of 100 µL hydrogels forming a sandwich-like structure. The encapsulated hMSCs were cultured in two sets of media, chondrogenic (C) and non-chondrogenic (nC) media along with addition of BMP-3 (10ng/mL) and IL-1β (10ng/mL). To study the combined effects of BMP-3 and IL-1β, the encapsulated hMSCs were first pre-treated with relevant media containing IL-1β for 24 hours, and then the media was replaced by media containing BMP-3 for the remaining experimental time period. IL-1β pre-treatment was carried out in both C and nC media. The samples were collected at day 7, 14, and 28.

RESULTS:

Proliferation and differentiation of hMSCs into chondrocyte-like cells was observed in all samples. Proteoglycans accumulation was observed in pre-treatment samples in C media. The protein and gene expression of Sox-9 and COL2A1 respectively, showed the occurrence of chondrogenesis in all samples.

CONCLUSION:

High cell viability, proliferation and differentiation was achieved in this in vitro model confirming that BMP-3 alone in the absence of TGF-β could drive hMSCs into chondrogenic lineage. Pre-treatment with IL-1β followed by BMP-3 stimulation resulted in high proteoglycans accumulation compared to stimulation with growth factors or cytokine alone. This suggests that pre-treatment with a pro-inflammatory cytokine before driving them into a chondrogeneic lineage might be of importance also in vivo.