Modification of Mesenchymal Stem/Stromal Cell-Derived Small Extracellular Vesicles by Calcitonin Gene Related Peptide (CGRP) Antagonist: Potential Implications for Inflammation and Pain Reversal

During the progression of knee osteoarthritis (OA), the synovium and infrapatellar fat pad (IFP) can serve as source for Substance P (SP) and calcitonin gene-related peptide (CGRP), two important pain-transmitting, immune, and inflammation modulating neuropeptides. Our previous studies showed that infrapatellar fat pad-derived mesenchymal stem/stromal cells (MSC) acquire a potent immunomodulatory phenotype and actively degrade Substance P via CD10 both in vitro and in vivo. On this basis, our hypothesis is that CD10-bound IFP-MSC sEVs can be engineered to target CGRP while retaining their anti-inflammatory phenotype. Herein, human IFP-MSC cultures were transduced with an adeno-associated virus (AAV) vector carrying a GFP-labelled gene for a CGRP antagonist peptide (aCGRP). The GFP positive aCGRP IFP-MSC were isolated and their sEVs' miRNA and protein cargos were assessed using multiplex methods. Our results showed that purified aCGRP IFP-MSC cultures yielded sEVs with cargo of 147 distinct MSC-related miRNAs. Reactome analysis of miRNAs detected in these sEVs revealed strong involvement in the regulation of target genes involved in pathways that control pain, inflammation and cartilage homeostasis. Protein array of the sEVs cargo demonstrated high presence of key immunomodulatory and reparative proteins. Stimulated macrophages exposed to aCGRP IFP-MSC sEVs demonstrated a switch towards an alternate M2 status. Also, stimulated cortical neurons exposed to aCGRP IFP-MSC sEVs modulate their molecular pain signaling profile. Collectively, our data suggest that yielded sEVs can putatively target CGRP in vivo, while containing potent anti-inflammatory and analgesic cargo, suggesting the promise for novel sEVs-based therapeutic approaches to diseases such as OA.

CD10-Bound Human Mesenchymal Stem/Stromal Cell-Derived Small Extracellular Vesicles Possess Immunomodulatory Cargo and Maintain Cartilage Homeostasis under Inflammatory Conditions

The onset and progression of human inflammatory joint diseases are strongly associated with the activation of resident synovium/infrapatellar fat pad (IFP) pro-inflammatory and pain-transmitting signaling. We recently reported that intra-articularly injected IFP-derived mesenchymal stem/stromal cells (IFP-MSC) acquire a potent immunomodulatory phenotype and actively degrade substance P (SP) via neutral endopeptidase CD10 (neprilysin). Our hypothesis is that IFP-MSC robust immunomodulatory therapeutic effects are largely exerted via their CD10-bound small extracellular vesicles (IFP-MSC sEVs) by attenuating synoviocyte pro-inflammatory activation and articular cartilage degradation. Herein, IFP-MSC sEVs were isolated from CD10High- and CD10Low-expressing IFP-MSC cultures and their sEV miRNA cargo was assessed using multiplex methods. Functionally, we interrogated the effect of CD10High and CD10Low sEVs on stimulated by inflammatory/fibrotic cues synoviocyte monocultures and cocultures with IFP-MSC-derived chondropellets. Finally, CD10High sEVs were tested in vivo for their therapeutic capacity in an animal model of acute synovitis/fat pad fibrosis. Our results showed that CD10High and CD10Low sEVs possess distinct miRNA profiles. Reactome analysis of miRNAs highly present in sEVs showed their involvement in the regulation of six gene groups, particularly those involving the immune system. Stimulated synoviocytes exposed to IFP-MSC sEVs demonstrated significantly reduced proliferation and altered inflammation-related molecular profiles compared to control stimulated synoviocytes. Importantly, CD10High sEV treatment of stimulated chondropellets/synoviocyte cocultures indicated significant chondroprotective effects. Therapeutically, CD10High sEV treatment resulted in robust chondroprotective effects by retaining articular cartilage structure/composition and PRG4 (lubricin)-expressing cartilage cells in the animal model of acute synovitis/IFP fibrosis. Our study suggests that CD10High sEVs possess immunomodulatory miRNA attributes with strong chondroprotective/anabolic effects for articular cartilage in vivo. The results could serve as a foundation for sEV-based therapeutics for the resolution of detrimental aspects of immune-mediated inflammatory joint changes associated with conditions such as osteoarthritis (OA).

CD10/Neprilysin Enrichment in Infrapatellar Fat Pad-Derived Mesenchymal Stem Cells Under Regulatory-Compliant Conditions: Implications for Efficient Synovitis and Fat Pad Fibrosis Reversal

BACKGROUND

Synovitis and infrapatellar fat pad (IFP) fibrosis participate in various conditions of the knee. Substance P (SP), a neurotransmitter secreted within those structures and historically associated with nociception, also modulates local neurogenic inflammatory and fibrotic responses. Exposure of IFP mesenchymal stem cells (IFP-MSCs) to a proinflammatory/profibrotic environment (ex vivo priming with TNFα, IFNγ, and CTGF) induces their expression of CD10/neprilysin, effectively degrading SP in vitro and in vivo.

PURPOSE/HYPOTHESIS

The purpose was to test the therapeutic effects of IFP-MSCs processed under regulatory-compliant protocols, comparing them side-by-side with standard fetal bovine serum (FBS)-grown cells. The hypothesis was that when processed under such protocols, IFP-MSCs do not require ex vivo priming to acquire a CD10-rich phenotype efficiently degrading SP and reversing synovitis and IFP fibrosis.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human IFP-MSCs were processed in FBS or either of 2 alternative conditions-regulatory-compliant pooled human platelet lysate (hPL) and chemically reinforced medium (Ch-R)-and then subjected to proinflammatory/profibrotic priming with TNFα, IFNγ, and CTGF. Cells were assessed for in vitro proliferation, stemness, immunophenotype, differentiation potential, transcriptional and secretory profiles, and SP degradation. Based on a rat model of acute synovitis and IFP fibrosis, the in vivo efficacy of cells degrading SP plus reversing structural signs of inflammation and fibrosis was assessed.

RESULTS

When compared with FBS, IFP-MSCs processed with either hPL or Ch-R exhibited a CD10^High phenotype and showed enhanced proliferation, differentiation, and immunomodulatory transcriptional and secretory profiles (amplified by priming). Both methods recapitulated and augmented the secretion of growth factors seen with FBS plus priming, with some differences between them. Functionally, in vitro SP degradation was more efficient in hPL and Ch-R, confirmed upon intra-articular injection in vivo where CD10-rich IFP-MSCs also dramatically reversed signs of synovitis and IFP fibrosis even without priming or at significantly lower cell doses.

CONCLUSION

hPL and Ch-R formulations can effectively replace FBS plus priming to induce specific therapeutic attributes in IFP-MSCs. The resulting fine-tuned, regulatory-compliant, cell-based product has potential future utilization as a novel minimally invasive cell therapy for the treatment of synovitis and IFP fibrosis.

CLINICAL RELEVANCE

The therapeutic enhancement of IFP-MSCs manufactured under regulatory-compliant conditions suggests that such a strategy could accelerate the time from preclinical to clinical phases. The therapeutic efficacy obtained at lower MSC numbers than currently needed and the avoidance of cell priming for efficient results could have a significant effect on the design of clinical protocols to potentially treat conditions involving synovitis and IFP fibrosis.

Functional Recovery in Osteoarthritic Chondrocytes Through Hyaluronic Acid and Platelet-Rich Plasma-Inhibited Infrapatellar Fat Pad Adipocytes

BACKGROUND

Recent studies have shown evidence that higher adiposity in the infrapatellar fat pad (IFP) induces inflammatory phenotypes in the knee joint and thereby contributes to the development and progression of osteoarthritis (OA). In particular, IFP adipocyte-derived inflammatory cytokines participate in pathological events. Our previous research has already addressed the therapeutic efficacy of hyaluronic acid and platelet-rich plasma (HA+PRP), including the promotion of cartilage regeneration and the inhibition of inflammation. The current study aimed to explore the remedial action of coadministered HA+PRP in OA recovery via IFP adipocyte inhibition.

HYPOTHESIS

HA+PRP repairs OA articular cartilage by inhibiting the release of adipokines from IFP adipocytes.

STUDY DESIGN

Controlled laboratory study.

METHODS

IFP adipocytes and articular chondrocytes were obtained from 10 patients with OA, and the effects of releasates containing cytokines and adipokines in IFP adipocyte-derived conditioned medium (IACM) on articular chondrocytes and IFP adipocytes themselves were evaluated. The therapeutic efficacy of exogenous HA+PRP was determined through its administration to cocultured IFP adipocytes and articular chondrocytes and further demonstrated in a 3-dimensional (3D) arthritic neocartilage model.

RESULTS

The IACM and IFP adipocyte-induced microenvironment could induce dedifferentiated and inflammatory phenotypes in articular chondrocytes. HA+PRP decreased the inflammatory potential of IFP adipocytes through the profound inhibition of cytokines and adipokines. The IACM-mediated and -reduced cartilaginous extracellular matrix could also be recovered through HA+PRP in the 3D arthritic neocartilage model.

CONCLUSION

IFP adipocyte-derived releasates mediated inflammatory response dedifferentiation in chondrocytes, which was recovered through HA+PRP administration.

CLINICAL RELEVANCE

Our findings demonstrated that HA+PRP effectively diminished IFP adipocyte-promoted inflammation in articular chondrocytes, indicating that the IFP could be a potential therapeutic target for OA therapy.