Mesenchymal stem cell-derived secretome enhances nucleus pulposus cell metabolism and modulates extracellular matrix gene expression in vitro

[Mechanism of extracellular vesicles in the repair of intervertebral disc degeneration]

Extracellular vesicles (EVs), defined as cell-secreted nanoscale vesicles that carry bioactive molecules, have emerged as a promising therapeutic strategy in tumor and tissue regeneration. Their potential in repairing intervertebral disc degeneration (IDD) through multidimensional regulatory mechanisms is a rapidly advancing field of research. This paper provided an overview of the mechanisms of EVs in IDD repair, thoroughly reviewed recent literature on EVs for IDD, domestically and internationally, and summarized their therapeutic mechanisms. In IDD repair, EVs could act through different mechanisms at the molecular, cellular, and tissue levels. At the molecular level, EVs could treat IDD by inhibiting inflammatory reactions, suppressing oxidative stress, and regulating the synthesis and decomposition of extracellular matrix. At the cellular level, EVs could treat IDD by inhibiting cellular pyroptosis, ferroptosis, and apoptosis and promoting cell proliferation and differentiation. At the tissue level, EVs could treat IDD by inhibiting neovascularization. EVs have a strong potential for clinical application in the treatment of IDD and deserve more profound study.

Advancements in Degenerative Disc Disease Treatment: A Regenerative Medicine Approach

Regenerative medicine represents a transformative approach to treating nucleus pulposus degeneration and offers hope for patients suffering from chronic low back pain due to disc degeneration. By focusing on restoring the natural structure and function of the nucleus pulposus rather than merely alleviating symptoms, these innovative therapies hold the potential to significantly improve patient outcomes. As research continues to advance in this field, we may soon witness a paradigm shift in how we approach spinal health and degenerative disc disease. The main purpose of this review is to provide an overview of the various regenerative approaches that target the restoration of the nucleus pulposus, a primary site for initiation of intervertebral disc degeneration.

Can treatment with human mesenchymal stem cells rescue the degenerative disc phenotype? An in vitro pilot study of induced cytokine expression

BACKGROUND CONTEXT

Given the relatively low cell density in degenerative discs, strategies intended to bolster disc cellularity through stem cell injections have come into clinical use. Stem cell therapy is meant to provide a source of viable disc cells that can promote a healthy disc phenotype. Nevertheless, there is a limited understanding of the mechanisms through which stem cell therapy impacts degeneration.

PURPOSE

The objectives of this pilot study were: 1) to evaluate gene expression changes associated with an in vitro induced degenerative phenotype in human nucleus pulposus (NP) cells, 2) to co-culture these degenerative NP cells with human mesenchymal stem cells (hMSCs) and investigate the impact this has on gene expression, 3) to investigate possible mechanisms by which hMSCs may impact the degenerative phenotype.

STUDY DESIGN

Laboratory study.

METHODS

NP cells were isolated and cultured from patients undergoing anterior lumbar interbody fusion for degenerative disc disease. A degenerative phenotype was induced in cultured NP cells by treatment with an inflammatory protocol (10pg/ml IL-1β and 100pg/ml TNF-α) for 7 days. Gene expression of Treated NP cells was compared to Untreated NP cells via reverse transcriptase polymerase chain reaction. NP cells were then co-cultured with hMSCs in vitro and treated with the inflammatory protocol. Gene expression of Treated NP cells co-cultured with hMSCs was compared to Treated NP cells alone. Preliminary co-culture data demonstrated that IL-10 was uniquely and dramatically upregulated. Therefore, gene expression of Treated NP cells exposed to IL-10 for 24 hours was compared to Treated NP cells alone.

RESULTS

Treated NP cells compared to Control NP cells showed upregulation of numerous pro-inflammatory cytokines, including CXCL5, IL-8, and IL-6 and downregulation of several antiinflammatory cytokines, including IL-10. After co-culture of Treated NP cells with hMSCs, a significant increase in gene expression was identified in IL-10 (+15.34 fold), BMP-6 (+2.32 fold), and LIF (+2.14 fold). A significant decrease in gene expression (p<.05) was seen in CCL7 (-2.03) and CXCL12 (-1.67). Exposure of Treated NP cells to IL-10 resulted in upregulation of COL-2 (+1.55 fold, p=.013) and downregulation of IL-8 (-1.4 fold), CXCL-5 (-1.58 fold,), and MMP-3 (-2.02 fold).

CONCLUSION

This in vitro pilot study shows that co-culture of degenerative phenotype NP cells with hMSCs produces multiple gene regulatory changes associated with an antiinflammatory phenotype. Additionally, exposure of degenerative phenotype NP cells to IL-10 produces gene regulation associated with both antiinflammatory and pro-extracellular matrix effects.

CLINICAL SIGNIFICANCE

These findings provide mechanistic support for the use of stem cell therapy as a strategy to decrease the pro-inflammatory molecular environment associated with disc degeneration. Additionally, given the challenges with the viability of hMSCs in the disc microenvironment, IL-10 may be another potential candidate for future targeted therapies for disc degeneration.

Tissue integrity and healing response in hypoestrogenic animal model treated by mesh implantation with addition of mesenchymal stem cell secretome

Background

Pelvic organ prolapse increases in prevalence and incidence in older women and hypoestrogenic conditions. Treatment with native tissue surgery has a fairly high recurrence rate. Mesh-augmented surgery is one of the most promising treatments for pelvic organ prolapse, with high effectiveness and low recurrence. Mesh-augmented surgery has a side effect of tissue erosion. The addition of secretome is expected to improve tissue integrity and reduce tissue erosion.

Aim

This study aimed to investigate the effect of adding the umbilical cord mesenchymal stem cell (UC-MSC) secretome on preventing tissue inflammatory responses, improving tissue integrity, and accelerating wound healing.

Methods

A total of 32 female New Zealand white rabbit hypoestrogenic models were divided into two groups: the control group with normal mesh and the secretome group with artificial mesh. Hypoestrogenic models were created using the bilateral ovariectomy method. Mesh implantation was performed using a surgical method on hypoestrogenic rabbits. The animals were euthanized on days 7, 14, 28, and 90 after mesh implantation. Histopathology parameters included angiogenesis formation, fibroblast number, and collagen deposition area.

Result

The results of this study showed that the number of angiogenesis, fibroblast, and collagen deposition data in the secretome group showed higher significantly (p < 0.05) than those in the control group on days 7, 14, 28, and 90 post mesh implantation. The formation of new blood vessels (angiogenesis) in the secretome group demonstrated a mean value of 9.81 ± 2.2 compared to 0.37 ± 0.03 in the control. The number of fibroblasts in the secretome group averaged 151.00 ± 8.14, in contrast to 34.00 ± 13.37 in the control group. Collagen formation in the secretome group was also higher, with a mean value of 80.02 ± 6.71 compared to 59.49 ± 4.61 in the control group over 90 days of observation.

Conclusion

The administration of secretomes from UC-MSC improved tissue integrity and accelerated wound healing.

Tissue integrity and healing response in hypoestrogenic animal model treated by mesh implantation with addition of mesenchymal stem cell secretome

Background

Pelvic organ prolapse increases in prevalence and incidence in older women and hypoestrogenic conditions. Treatment with native tissue surgery has a fairly high recurrence rate. Mesh-augmented surgery is one of the most promising treatments for pelvic organ prolapse, with high effectiveness and low recurrence. Mesh-augmented surgery has a side effect of tissue erosion. The addition of secretome is expected to improve tissue integrity and reduce tissue erosion.

Aim

This study aimed to investigate the effect of adding the umbilical cord mesenchymal stem cell (UC-MSC) secretome on preventing tissue inflammatory responses, improving tissue integrity, and accelerating wound healing.

Methods

A total of 32 female New Zealand white rabbit hypoestrogenic models were divided into two groups: the control group with normal mesh and the secretome group with artificial mesh. Hypoestrogenic models were created using the bilateral ovariectomy method. Mesh implantation was performed using a surgical method on hypoestrogenic rabbits. The animals were euthanized on days 7, 14, 28, and 90 after mesh implantation. Histopathology parameters included angiogenesis formation, fibroblast number, and collagen deposition area.

Result

The results of this study showed that the number of angiogenesis, fibroblast, and collagen deposition data in the secretome group showed higher significantly (p < 0.05) than those in the control group on days 7, 14, 28, and 90 post mesh implantation. The formation of new blood vessels (angiogenesis) in the secretome group demonstrated a mean value of 9.81 ± 2.2 compared to 0.37 ± 0.03 in the control. The number of fibroblasts in the secretome group averaged 151.00 ± 8.14, in contrast to 34.00 ± 13.37 in the control group. Collagen formation in the secretome group was also higher, with a mean value of 80.02 ± 6.71 compared to 59.49 ± 4.61 in the control group over 90 days of observation.

Conclusion

The administration of secretomes from UC-MSC improved tissue integrity and accelerated wound healing.

Application of mesenchymal stem cells in liver fibrosis and regeneration

Liver transplantation remains the most effective treatment for end-stage liver disease (ESLD), but it is fraught with challenges such as immunosuppression, high risk and cost, and donor shortage. In recent years, stem cell transplantation has emerged as a promising new strategy for ESLD treatment, with mesenchymal stem cells (MSCs) gaining significant attention because of their unique properties. MSCs can regulate signaling pathways, including hepatocyte growth factor/c-Met, Wnt/beta (β)-catenin, Notch, transforming growth factor-β1/Smad, interleukin-6/Janus kinase/signal transducer and activator of transcription 3, and phosphatidylinositol 3-kinase/PDK/Akt, thereby influencing the progression of liver fibrosis and regeneration. As a promising stem cell type, MSCs offer numerous advantages in liver disease treatment, including low immunogenicity; ease of acquisition; unlimited proliferative ability; pluripotent differentiation potential; immunomodulatory function; and anti-inflammatory, antifibrotic, and antiapoptotic biological characteristics. This review outlines the mechanisms by which MSCs reverse liver fibrosis and promote liver regeneration. MSCs are crucial in reversing liver fibrosis and repairing liver damage through the secretion of growth factors, regulation of signaling pathways, and modulation of immune responses. MSCs have shown good therapeutic effects in preclinical and clinical studies, providing new strategies for liver disease treatment. However, challenges still exist in the clinical application of MSCs, including low differentiation efficiency and limited sources. This review provides a reference for MSC application in liver disease treatment. With the continuous progress in MSC research, MSCs are expected to achieve breakthroughs in liver disease treatment, thereby improving patient treatment outcomes.

Allogenic bone marrow-derived mesenchymal stromal cell-based therapy for patients with chronic low back pain: a prospective, multicentre, randomised placebo controlled trial (RESPINE study)

OBJECTIVES

To assess the efficacy of a single intradiscal injection of allogeneic bone marrow mesenchymal stromal cells (BM-MSCs) versus a sham placebo in patients with chronic low back pain (LBP).

METHODS

Participants were randomised in a prospective, double-blind, controlled study to receive either sham injection or intradiscal injection of 20 million allogeneic BM-MSC, between April 2018 and December 2022. The first co-primary endpoint was the rate of responders defined by improvement of the Visual Analogue Scale (VAS) for pain of at least 20% and 20 mm, or improvement of the Oswestry Disability Index (ODI) of 20% between baseline and month 12. The secondary structural co-primary endpoint was assessed by the disc fluid content measured by quantitative MRI T2, between baseline and month 12. Secondary endpoints included pain VAS, ODI, the Short Form (SF)-36 and the minimal clinically important difference in all timepoints (1, 3, 6, 12 and 24 months). We determined the immune response associated with allogeneic cell injection between baseline and 6 months. Serious adverse events (SAEs) were recorded.

RESULTS

114 patients were randomised (n=58, BM-MSC group; n=56, sham placebo group). At 12 months, the primary outcome was not reached (74% in the BM-MSC group vs 69% in the placebo group; p=0.77). The groups did not differ in all secondary outcomes. No SAE related to the intervention occurred.

CONCLUSIONS

While our study did not conclusively demonstrate the efficacy of allogeneic BM-MSCs for LBP, the procedure was safe. Long-term outcomes of MSC therapy for LBP are still being studied.

TRIAL REGISTRATION NUMBER

EudraCT 2017-002092-25/ClinicalTrials.gov: NCT03737461.

Potential Consequences of the Use of Adipose-Derived Stem Cells in the Treatment of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) ranks as the most prevalent of primary liver cancers and stands as the third leading cause of cancer-related deaths. Early-stage HCC can be effectively managed with available treatment modalities ranging from invasive techniques, such as liver resection and thermoablation, to systemic therapies primarily employing tyrosine kinase inhibitors. Unfortunately, these interventions take a significant toll on the body, either through physical trauma or the adverse effects of pharmacotherapy. Consequently, there is an understandable drive to develop novel HCC therapies. Adipose-derived stem cells (ADSCs) are a promising therapeutic tool. Their facile extraction process, coupled with the distinctive immunomodulatory capabilities of their secretome, make them an intriguing subject for investigation in both oncology and regenerative medicine. The factors they produce are both enzymes affecting the extracellular matrix (specifically, metalloproteinases and their inhibitors) as well as cytokines and growth factors affecting cell proliferation and invasiveness. So far, the interactions observed with various cancer cell types have not led to clear conclusions. The evidence shows both inhibitory and stimulatory effects on tumor growth. Notably, these effects appear to be dependent on the tumor type, prompting speculation regarding their potential inhibitory impact on HCC. This review briefly synthesizes findings from preclinical and clinical studies examining the effects of ADSCs on cancers, with a specific focus on HCC, and emphasizes the need for further research.

Getting to the Core: Exploring the Embryonic Development from Notochord to Nucleus Pulposus

The intervertebral disc (IVD) is the largest avascular organ of the human body and plays a fundamental role in providing the spine with its unique structural and biomechanical functions. The inner part of the IVD contains the nucleus pulposus (NP), a gel-like tissue characterized by a high content of type II collagen and proteoglycans, which is crucial for the disc's load-bearing and shock-absorbing properties. With aging and IVD degeneration (IDD), the NP gradually loses its physiological characteristics, leading to low back pain and additional sequelae. In contrast to surrounding spinal tissues, the NP presents a distinctive embryonic development since it directly derives from the notochord. This review aims to explore the embryology of the NP, emphasizing the pivotal roles of key transcription factors, which guide the differentiation and maintenance of the NP cellular components from the notochord and surrounding sclerotome. Through an understanding of NP development, we sought to investigate the implications of the critical developmental aspects in IVD-related pathologies, such as IDD and the rare malignant chordomas. Moreover, this review discusses the therapeutic strategies targeting these pathways, including the novel regenerative approaches leveraging insights from NP development and embryology to potentially guide future treatments.

ISSLS PRIZE in Basic Science 2024: superiority of nucleus pulposus cell- versus mesenchymal stromal cell-derived extracellular vesicles in attenuating disc degeneration and alleviating pain

PURPOSE

To investigate the therapeutic potential of extracellular vesicles (EVs) derived from human nucleus pulposus cells (NPCs), with a specific emphasis on Tie2-enhanced NPCs, compared to EVs derived from human bone marrow-derived mesenchymal stromal cells (BM-MSCs) in a coccygeal intervertebral disc degeneration (IDD) rat model.

METHODS

EVs were isolated from healthy human NPCs cultured under standard (NPCSTD-EVs) and Tie2-enhancing (NPCTie2+-EVs) conditions. EVs were characterized, and their potential was assessed in vitro on degenerative NPCs in terms of cell proliferation and senescence, with or without 10 ng/mL interleukin (IL)-1β. Thereafter, 16 Sprague-Dawley rats underwent annular puncture of three contiguous coccygeal discs to develop IDD. Phosphate-buffered saline, NPCSTD-EVs, NPCTie2+-EVs, or BM-MSC-derived EVs were injected into injured discs, and animals were followed for 12 weeks until sacrifice. Behavioral tests, radiographic disc height index (DHI) measurements, evaluation of pain biomarkers, and histological analyses were performed to assess the outcomes of injected EVs.

RESULTS

NPC-derived EVs exhibited the typical exosomal morphology and were efficiently internalized by degenerative NPCs, enhancing cell proliferation, and reducing senescence. In vivo, a single injection of NPC-derived EVs preserved DHI, attenuated degenerative changes, and notably reduced mechanical hypersensitivity. MSC-derived EVs showed marginal improvements over sham controls across all measured outcomes.

CONCLUSION

Our results underscore the regenerative potential of young NPC-derived EVs, particularly NPCTie2+-EVs, surpassing MSC-derived counterparts. These findings raise questions about the validity of MSCs as both EV sources and cellular therapeutics against IDD. The study emphasizes the critical influence of cell type, source, and culture conditions in EV-based therapeutics.

Wharton's Jelly mesenchymal stromal cell-derived extracellular vesicles promote nucleus pulposus cell anabolism in an in vitro 3D alginate-bead culture model

Background

Intradiscal transplantation of mesenchymal stromal cells (MSCs) has emerged as a promising therapy for intervertebral disc degeneration (IDD). However, the hostile microenvironment of the intervertebral disc (IVD) may compromise the survival of implanted cells. Interestingly, studies reported that paracrine factors, such as extracellular vesicles (EVs) released by MSCs, may regenerate the IVD. The aim of this study was to investigate the therapeutic effects of Wharton's Jelly MSC (WJ-MSC)-derived EVs on human nucleus pulposus cells (hNPCs) using an in vitro 3D alginate-bead culture model.

Methods

After EV isolation and characterization, hNPCs isolated from surgical specimens were encapsulated in alginate beads and treated with 10, 50, and 100 μg/mL WJ-MSC-EVs. Cell proliferation and viability were assessed by flow cytometry and live/dead staining. Nitrite and glycosaminoglycan (GAG) content was evaluated through Griess and 1,9-dimethylmethylene blue assays. hNPCs in alginate beads were paraffin-embedded and stained for histological analysis (hematoxylin-eosin and Alcian blue) to assess extracellular matrix (ECM) composition. Gene expression levels of catabolic (MMP1, MMP13, ADAMTS5, IL6, NOS2), anabolic (ACAN), and hNPC marker (SOX9, KRT19) genes were analyzed through qPCR. Collagen type I and type II content was assessed with Western blot analysis.

Results

Treatment with WJ-MSC-EVs resulted in an increase in cell content and a decrease in cell death in degenerated hNPCs. Nitrite production was drastically reduced by EV treatment compared to the control. Furthermore, proteoglycan content was enhanced and confirmed by Alcian blue histological staining. EV stimulation attenuated ECM degradation and inflammation by suppressing catabolic and inflammatory gene expression levels. Additionally, NPC phenotypic marker genes were also maintained by the EV treatment.

Conclusions

WJ-MSC-derived EVs ameliorated hNPC growth and viability, and attenuated ECM degradation and oxidative stress, offering new opportunities for IVD regeneration as an attractive alternative strategy to cell therapy, which may be jeopardized by the harsh microenvironment of the IVD.

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.

Can extracellular vesicles be considered as a potential frontier in the treatment of intervertebral disc disease?

As a global public health problem, low back pain (LBP) caused by intervertebral disc degeneration (IDD) seriously affects patients' quality of life. In addition, the prevalence of IDD tends to be younger, which brings a huge burden to individuals and society economically. Current treatments do not delay or reverse the progression of IDD. The emergence of biologic therapies has brought new hope for the treatment of IDD. Among them, extracellular vesicles (EVs), as nanoscale bioactive substances that mediate cellular communication, have now produced many surprising results in the research of the treatment of IDD. This article reviews the mechanisms and roles of EVs in delaying IDD and describes the prospects and challenges of EVs.

Irisin inhibits tenocyte response to inflammation in vitro: New insights into tendon-muscle cross-talk

Tendinopathy is one of the most common musculoskeletal disorders with significant repercussions on quality of life and sport activities. Physical exercise (PE) is considered the first-line approach to treat tendinopathy due renowned mechanobiological effects on tenocytes. Irisin, a recently identified myokine released during PE, has been recognized for several beneficial effects towards muscle, cartilage, bone, and intervertebral disc tissues. The aim of this study was to evaluate the effects of irisin on human primary tenocytes (hTCs) in vitro. Human tendons were harvested from specimens of patients undergoing anterior cruciate ligament reconstruction (n = 4). After isolation and expansion, hTCs were treated with RPMI medium (negative control), interleukin (IL)-1β or tumor necrosis factor-α (TNF-α) (positive controls; 10 ng/mL), irisin (5, 10, 25 ng/mL), IL-1β or TNF-α pretreatment and subsequent co-treatment with irisin, pretreatment with irisin and subsequent co-treatment with IL-1β or TNF-α. hTC metabolic activity, proliferation, and nitrite production were evaluated. Detection of unphosphorylated and phosphorylated p38 and ERK was performed. Tissue samples were analyzed by histology and immunohistochemistry to evaluate irisin αVβ5 receptor expression. Irisin significantly increased hTC proliferation and metabolic activity, while reducing the production of nitrites both before and after the addition of IL-1β and TNF-α. Interestingly, irisin reduced p-p38 and pERK levels in inflamed hTCs. The αVβ5 receptor was uniformly expressed on hTC plasma membranes, supporting the potential binding of irisin. This is the first study reporting the capacity of irisin to target hTCs and modulating their response to inflammatory stresses, possibly orchestrating a biological crosstalk between the muscle and tendon.