Abstract
Placenta-derived mesenchymal stromal cells (PMSCs) provide a promising cell source for tissue regeneration. However, rapid induction of PMSC chondrogenic differentiation during therapeutic transplantation remains extremely challenging. Here we undertook a study to determine if Notch inhibition by soluble Jagged1 (JAG1) peptides could be utilized to accelerate PMSC-induced cartilage regeneration in a mouse post-traumatic osteoarthritis (PTOA) model. Our results showed that treatment of PMSCs with soluble JAG1 significantly enhanced chondrogenesis in culture as shown by increased alcian blue staining and decreased Notch target Hes1 expression when compared to those in lgG-treated control cells. Importantly, significantly enhanced cartilage formation and decreased joint inflammation were observed when JAG1-treated PMSCs were injected into mouse PTOA knee joints. Finally, in vivo cell tracing showed that more JAG1-treated PMSCs remained in knee joint tissues and that JAG1-treated PMSCs exhibited greater PMSC chondrogenic differentiation than lgG-treated control PMSCs at 4 weeks after injection. These data indicate that transient Notch inhibition by soluble JAG1 could be used to enhance PMSC survival and chondrogenic differentiation, thereby increasing the therapeutic potential of PMSCs for cartilage regeneration.
Highlights
Mesenchymal stromal cells (PMSCs) derived from placental tissue are highly proliferative with multipotent differentiation capacity[1]
Since MSCs are known to home to diseased tissue and are preferentially attracted to diseased tissue rather than to intact tissue[4], intra-articular injection of MSCs has been widely used to adenoviral JAG1 transduction of human MSCs, which caused continuous expression of JAG1 and sustained Notch signaling, completely blocked chondrogenesis[24], suggesting that inhibition of Notch signaling is critical for MSC chondrogenic differentiation
Soluble JAG1 is able to induce rapid Placenta-derived mesenchymal stromal cells (PMSCs) chondrogenesis ex vivo, whether it can be translated to a treatment for cartilage repair is not known
Summary
Human PMSC isolation and culture Placentas delivered by normal pregnant women were collected immediately after delivery. The procedures for PMSC isolation and culture were performed as described before[3]. Pellets were cultured for 14 days in 0.5 ml of serum-free MesenCultTM-Chondrogenic differentiation medium (Stem cell Technologies, Vancouver, Canada) containing soluble JAG1 (10 μg/ml) or lgG (10 μg/ml) peptides. Tissue sections were observed using a fluorescence microscope for labeled PMSCs and stained with H&E and alcian blue/orange G for histological scoring. IHC for tracing human cells in knee joint tissue was performed using anti-human nuclear antigen antibody (ab191181, Abcam, USA). RT-PCRs were performed on ABI 7900HT fast Real-Time PCR System using primers for Notch target Hes[1], chondrogenic (ColII, Aggrecan and SOX9), osteogenic (Runx[2] and Osteocalcin), adipogenic (PPARr and C/EBPa), and proinflammation (TNF-α, IL-1β, MMP-1, MMP-13) marker genes.
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