BMP-3 Promotes Matrix Production in Co-cultured Stem Cells and Disc Cells from Low Back Pain Patients

A new strategy for intervertebral disc regeneration: The synergistic potential of mesenchymal stem cells and their extracellular vesicles with hydrogel scaffolds

Intervertebral disc degeneration (IDD) is a disease that severely affects spinal health and is prevalent worldwide. Mesenchymal stem cells (MSCs) and their derived extracellular vesicles (EVs) have regenerative potential and have emerged as promising therapeutic tools for treating degenerative discs. However, challenges such as the harsh microenvironment of degenerated intervertebral discs and EVs' limited stability and efficacy have hindered their clinical application. In recent years, hydrogels have attracted much attention in the field of IDD therapy because they can mimic the physiologic microenvironment of the disc and provide a potential solution by providing a suitable growth environment for MSCs and EVs. This review introduced the biological properties of MSCs and their derived EVs, summarized the research on the application of MSCs and EVs in IDD, summarized the current clinical trial studies of MSCs and EVs, and also explored the mechanism of action of MSCs and EVs in intervertebral discs. In addition, plenty of research elaborated on the mechanism of action of different classified hydrogels in tissue engineering, the synergistic effect of MSCs and EVs in promoting intervertebral disc regeneration, and their wide application in treating IDD. Finally, the challenges and problems still faced by hydrogel-loaded MSCs and EVs in the treatment of IDD are summarized, and potential solutions are proposed. This paper outlines the synergistic effects of MSCs and EVs in treating IDD in combination with hydrogels and aims to provide theoretical references for future related studies.

Reviving Intervertebral Discs: Treating Degeneration Using Advanced Delivery Systems

Intervertebral disc degeneration (IVDD) is commonly associated with many spinal problems, such as low back pain, and significantly impacts a patient's quality of life. However, current treatments for IVDD, which include conservative and surgical methods, are limited in their ability to fully address degeneration. To combat IVDD, delivery-system-based therapy has received extensive attention from researchers. These delivery systems can effectively deliver therapeutic agents for IVDD, overcoming the limitations of these agents, reducing leakage and increasing local concentration to inhibit IVDD or promote intervertebral disc (IVD) regeneration. This review first briefly introduces the structure and function of the IVD, and the related pathophysiology of IVDD. Subsequently, the roles of drug-based and bioactive-substance-based delivery systems in IVDD are highlighted. The former includes natural source drugs, nonsteroidal anti-inflammatory drugs, steroid medications, and other small molecular drugs. The latter includes chemokines, growth factors, interleukin, and platelet-rich plasma. Additionally, gene-based and cell-based delivery systems are briefly involved. Finally, the limitations and future development of the combination of therapeutic agents and delivery systems in the treatment of IVDD are discussed, providing insights for future research.

Effects of rAAV-mediated overexpression of bone morphogenetic protein 3 (BMP-3) on the chondrogenic fate of human bone marrow-derived mesenchymal stromal cells

Implantation of genetically modified chondrogenically competent human bone marrow-derived mesenchymal stromal cells (hMSCs) is an attractive strategy to improve cartilage repair. The goal of this study was to examine the potential benefits of transferring a sequence coding for the bone morphogenetic protein 3 (BMP-3) that modulates bone and cartilage formation, using recombinant adeno-associated virus (rAAV) vectors on the chondroreparative activities of hMSCs. Undifferentiated and chondrogenically induced primary human MSCs were treated with an rAAV-hBMP-3 construct to evaluate its effects on the proliferative, metabolic, and chondrogenic activities of the cells compared with control (reporter rAAV-lacZ vector) condition. Effective BMP-3 expression was noted both in undifferentiated and chondrogenically differentiated cells in the presence of rAAV-hBMP-3 relative to rAAV-lacZ, stimulating cell proliferation and extracellular matrix (proteoglycans, type-II collagen) deposition together with higher levels of chondrogenic SOX9 expression. rAAV-hBMP-3 also advantageously decreased terminal differentiation, hypertrophy, and osteogenesis (type-I/-X collagen and alkaline phosphatase expression), with reduced levels of osteoblast-related RUNX-2 transcription factor and β-catenin (osteodifferentiation mediator) and enhanced PTHrP expression (inhibitor of hypertrophic maturation, calcification, and bone formation). This study shows the advantage of modifying hMSCs with rAAV-hBMP-3 to trigger adapted chondroreparative activities as a source of improved cells for transplantation protocols in cartilage defects.

Extracellular vesicles from human mesenchymal stem cells expedite chondrogenesis in 3D human degenerative disc cell cultures

Background

Extracellular vesicles (EVs) from human mesenchymal stem cells (hMSCs) are known to be mediators of intercellular communication and have been suggested as possible therapeutic agents in many diseases. Their potential use in intervertebral disc (IVD) degeneration associated with low back pain (LBP) is yet to be explored. Since LBP affects more than 85% of the western population resulting in high socioeconomic consequences, there is a demand for exploring new and possibly mini-invasive treatment alternatives. In this study, the effect of hMSC-derived small EVs (sEVs) on degenerated disc cells (DCs) isolated from patients with degenerative discs and chronic LBP was investigated in a 3D in vitro model.

Methods

hMSCs were isolated from bone marrow aspirate, and EVs were isolated from conditioned media of the hMSCs by differential centrifugation and filtration. 3D pellet cultures of DCs were stimulated with the sEVs at 5 × 10¹⁰ vesicles/ml concentration for 28 days and compared to control. The pellets were harvested at days 7, 14, and 28 and evaluated for cell proliferation, viability, ECM production, apoptotic activity, chondrogenesis, and cytokine secretions.

Results

The findings demonstrated that treatment with sEVs from hMSCs resulted in more than 50% increase in cell proliferation and decrease in cellular apoptosis in degenerated DCs from this patient group. ECM production was also observed as early as in day 7 and was more than three times higher in the sEV-treated DC pellets compared to control cultures. Further, sEV treatment suppressed secretion of MMP-1 in the DCs.

Conclusion

hMSC-derived sEVs improved cell viability and expedited chondrogenesis in DCs from degenerated IVDs. These findings open up for new tissue regeneration treatment strategies to be developed for degenerative disorders of the spine.