A Systematic Study of the Effect of Different Molecular Weights of Hyaluronic Acid on Mesenchymal Stromal Cell-Mediated Immunomodulation

Fibrotic reaction to hyaluronic acid fillers in the face

BACKGROUND

Hyaluronic acids (HAs) can have very different actions not only depending on injector and host factors but also depending on their molecular weight. Whereas short chain HA has immunological activity long chain HA influences fibroblasts and may stimulate them to produce collagen. Although this is generally thought to be a positive feature it may be disadvantageous in certain localizations.

PATIENTS AND METHODS

We have encountered 23 patients who developed fibrous tissue next to the nasolabial folds accentuating them and becoming very obvious while smiling. Hyaluronidase injection did not reduce this mass.

RESULTS

Intralesional triamcinolone acetonide injection led to rapid improvement.

DISCUSSION

Fibrotic tissue reaction not responding to hyaluronidase may be the result of HA injection and can effectively be treated with intralesional steroid injection.

Enhancing Immunomodulatory Function of Mesenchymal Stromal Cells by Hydrogel Encapsulation

Mesenchymal stromal cells (MSCs) showcase remarkable immunoregulatory capabilities in vitro, positioning them as promising candidates for cellular therapeutics. However, the process of administering MSCs and the dynamic in vivo environment may impact the cell-cell and cell-matrix interactions of MSCs, consequently influencing their survival, engraftment, and their immunomodulatory efficacy. Addressing these concerns, hydrogel encapsulation emerges as a promising solution to enhance the therapeutic effectiveness of MSCs in vivo. Hydrogel, a highly flexible crosslinked hydrophilic polymer with a substantial water content, serves as a versatile platform for MSC encapsulation. Demonstrating improved engraftment and heightened immunomodulatory functions in vivo, MSCs encapsulated by hydrogel are at the forefront of advancing therapeutic outcomes. This review delves into current advancements in the field, with a focus on tuning various hydrogel parameters to elucidate mechanistic insights and elevate functional outcomes. Explored parameters encompass hydrogel composition, involving monomer type, functional modification, and co-encapsulation, along with biomechanical and physical properties like stiffness, viscoelasticity, topology, and porosity. The impact of these parameters on MSC behaviors and immunomodulatory functions is examined. Additionally, we discuss potential future research directions, aiming to kindle sustained interest in the exploration of hydrogel-encapsulated MSCs in the realm of immunomodulation.

Using biomaterials to improve mesenchymal stem cell therapies for chronic, nonhealing wounds

Historically, treatment of chronic, nonhealing wounds has focused on managing symptoms using biomaterial-based wound dressings, which do not adequately address the underlying clinical issue. Mesenchymal stem cells (MSCs) are a promising cell-based therapy for the treatment of chronic, nonhealing wounds, yet inherent cellular heterogeneity and susceptibility to death during injection limit their clinical use. Recently, researchers have begun to explore the synergistic effects of combined MSC-biomaterial therapies, where the biomaterial serves as a scaffold to protect the MSCs and provides physiologically relevant physicochemical cues that can direct MSC immunomodulatory behavior. In this review, we highlight recent progress in this field with a focus on the most commonly used biomaterials, classified based on their source, including natural biomaterials, synthetic biomaterials, and the combination of natural and synthetic biomaterials. We also discuss current challenges regarding the clinical translation of these therapies, as well as a perspective on the future outlook of the field.

Preclinical Studies and Clinical Trials on Cell-Based Treatments for Meniscus Regeneration

This study aims at performing a thorough review of cell-based treatment strategies for meniscus regeneration in preclinical and clinical studies. The PubMed, Embase, and Web of Science databases were searched for relevant studies (both preclinical and clinical) published from the time of database construction to December 2022. Data related to cell-based therapies for in situ regeneration of the meniscus were extracted independently by two researchers. Assessment of risk of bias was performed according to the Cochrane Handbook for Systematic Reviews of Interventions. Statistical analyses based on the classification of different treatment strategies were performed. A total of 5730 articles were retrieved, of which 72 preclinical studies and 6 clinical studies were included in this review. Mesenchymal stem cells (MSCs), especially bone marrow MSCs (BMSCs), were the most commonly used cell type. Among preclinical studies, rabbit was the most commonly used animal species, partial meniscectomy was the most commonly adopted injury pattern, and 12 weeks was the most frequently chosen final time point for assessing repair outcomes. A range of natural and synthetic materials were used to aid cell delivery as scaffolds, hydrogels, or other morphologies. In clinical trials, there was large variation in the dose of cells, ranging from 16 × 106 to 150 × 106 cells with an average of 41.52 × 106 cells. The selection of treatment strategy for meniscus repair should be based on the nature of the injury. Cell-based therapies incorporating various "combination" strategies such as co-culture, composite materials, and extra stimulation may offer greater promise than single strategies for effective meniscal tissue regeneration, restoring natural meniscal anisotropy, and eventually achieving clinical translation. Impact Statement This review provides an up-to-date and comprehensive overview of preclinical and clinical studies that tested cell-based treatments for meniscus regeneration. It presents novel perspectives on studies published in the past 30 years, giving consideration to the cell sources and dose selection, delivery methods, extra stimulation, animal models and injury patterns, timing of outcome assessment, and histological and biomechanical outcomes, as well as a summary of findings for individual studies. These unique insights will help to shape future research on the repair of meniscus lesions and inform the clinical translation of new cell-based tissue engineering strategies.

Intra-articular Hyaluronic Acid Treatments for Knee Osteoarthritis: A Systematic Review of Product Properties

INTRODUCTION

There are many intra-articular hyaluronic acid (IA-HA) products on the market that have known intrinsic differences in molecular size, source, and structure. The current review summarizes existing evidence describing and assessing these differences, while also identifying whether these differences have an impact on clinical outcomes.

METHODS

This systematic review summarized all literature that specifically addresses IA-HA product differences. Included studies summarized basic science and mechanism of action comparisons of IA-HA product differences, or systematic reviews that assess differences in clinical outcomes between IA-HA product differences.

RESULTS

A total of 20 investigations assessed basic science differences between IA-HA products, while 20 investigations provided assessments of the clinical outcome differences between IA-HA product characteristics. The published basic science literature provided a differentiation between low molecular weight (LMW) and high molecular weight (HMW) HA with regard to changes within the synovial fluid, driven by the interactions that these molecules have with receptors in the joint space. These differences in receptor interaction manifest within clinical outcomes, as meta-analyses comparing pain relief after IA-HA suggest that pain reduction is superior in patients who receive HMW HA as opposed to LMW HA.

CONCLUSION

This review highlights differences between IA-HA characteristics, and how important the molecular weight, derivation of the product, and structure are to variances in reported clinical outcomes to treat osteoarthritis (OA) of the knee. HMW IA-HAs have shown greater efficacy compared to the alternative of LMW products, while avian-derived and cross-linked products have potentially demonstrated an increase in inflammatory events over non-avian-derived, non-cross-linked HAs.

Putative critical quality attribute matrix identifies mesenchymal stromal cells with potent immunomodulatory and angiogenic "fitness" ranges in response to culture process parameters

Adipose-derived mesenchymal stromal cells (MSC(AT)) display immunomodulatory and angiogenic properties, but an improved understanding of quantitative critical quality attributes (CQAs) that inform basal MSC(AT) fitness ranges for immunomodulatory and/or angiogenic applications is urgently needed for effective clinical translation. We constructed an in vitro matrix of multivariate readouts to identify putative CQAs that were sensitive enough to discriminate between specific critical processing parameters (CPPs) chosen for their ability to enhance MSC immunomodulatory and angiogenic potencies, with consideration for donor heterogeneity. We compared 3D aggregate culture conditions (3D normoxic, 3D-N) and 2D hypoxic (2D-H) culture as non-genetic CPP conditions that augment immunomodulatory and angiogenic fitness of MSC(AT). We measured multivariate panels of curated genes, soluble factors, and morphometric features for MSC(AT) cultured under varying CPP and licensing conditions, and we benchmarked these against two functional and therapeutically relevant anchor assays - in vitro monocyte/macrophage (MΦ) polarization and in vitro angiogenesis. Our results showed that varying CPP conditions was the primary driver of MSC(AT) immunomodulatory fitness; 3D-N conditions induced greater MSC(AT)-mediated MΦ polarization toward inflammation-resolving subtypes. In contrast, donor heterogeneity was the primary driver of MSC(AT) angiogenic fitness. Our analysis further revealed panels of putative CQAs with minimum and maximum values that consisted of twenty MSC(AT) characteristics that informed immunomodulatory fitness ranges, and ten MSC(AT) characteristics that informed angiogenic fitness ranges. Interestingly, many of the putative CQAs consisted of angiogenic genes or soluble factors that were inversely correlated with immunomodulatory functions (THBS1, CCN2, EDN1, PDGFA, VEGFA, EDIL3, ANGPT1, and ANG genes), and positively correlated to angiogenic functions (VEGF protein), respectively. We applied desirability analysis to empirically rank the putative CQAs for MSC(AT) under varying CPP conditions and donors to numerically identify the desirable CPP conditions or donors with maximal MSC(AT) immunomodulatory and/or angiogenic fitness. Taken together, our approach enabled combinatorial analysis of the matrix of multivariate readouts to provide putative quantitative CQAs that were sensitive to variations in select CPPs that enhance MSC immunomodulatory/angiogenic potency, and donor heterogeneity. These putative CQAs may be used to prospectively screen potent MSC(AT) donors or cell culture conditions to optimize for desired basal MSC(AT) immunomodulatory or angiogenic fitness.

Immunomodulatory potential of secretome from cartilage cells and mesenchymal stromal cells in an arthritic context: From predictive fiction toward reality

The purpose of the present study is to predict by bioinformatics the activity of the extracellular vesicle (EV)-embedded micro RNA (miRNAs) secreted by cartilage cells (CCs), adipose tissue-derived- (ASCs), and bone marrow-derived stem cells (BMSCs) and verify their immunomodulatory potential supporting our bioinformatics findings to optimize the autologous cell-based therapeutic strategies for osteoarthritis (OA) management. Cells were isolated from surgical waste tissues of three patients who underwent total hip replacement, expanded and the EVs were collected. The expression of EV-embedded miRNA was evaluated with the QuantStudio 12 K Flex OpenArray^® platform. Mientournet and ingenuity pathway analysis (IPA) were used for validated target prediction analysis and to identify miRNAs involved in OA and inflammation. Cells shared the expression of 325 miRNAs embedded in EVs and differed for the expression of a small number of them. Mienturnet revealed no results for miRNAs selectively expressed by ASCs, whereas miRNA expressed by CCs and BMSCs were putatively involved in the modulation of cell cycle, senescence, apoptosis, Wingless and Int-1 (Wnt), transforming growth factor beta (TGFβ), vascular endothelial growth factor (VEGF), Notch, Hippo, tumor necrosis factor alpha (TNFα), interleukin 1 beta (IL-1β), insulin like growth factor 1 (IGF-1), RUNX family transcription factor 2 (RUNX2), and endochondral ossification pathways. Cartilage homeostasis, macrophages and T cells activity and inflammatory mediators were identified by IPA as targets of the miRNAs found in all the cell populations. Co-culture tests on macrophages and T cells confirmed the immuno-modulatory ability of CCs, ASCs, and BMSCs. The study findings support the rationale behind the use of cell-based therapy for the treatment of OA.

Hydrogel Encapsulation: Taking the Therapy of Mesenchymal Stem Cells and Their Derived Secretome to the Next Level

Biomaterials have long been the focus of research and hydrogels are representatives thereof. Hydrogels have attracted much attention in the medical sciences, especially as a candidate drug-carrier. Mesenchymal stem cells (MSC) and MSC-derived secretome are a promising therapeutic method, owing to the intrinsic therapeutic properties thereof. The low cell retention and poor survival rate of MSCs make further research difficult, which is a problem that hydrogel encapsulation largely solved. In this review, safety and feasibility of hydrogel-encapsulated MSCs, the improvement of the survival, retention, and targeting, and the enhancement of their therapeutic effect by hydrogels were studied. The status of the hydrogel-encapsulated MSC secretome was also discussed.

Advances in Encapsulation and Delivery Strategies for Islet Transplantation

Type 1 diabetes mellitus (T1DM) is a chronic metabolic disease caused by the destruction of pancreatic β-cells in response to autoimmune reactions. Shapiro et al. conducted novel islet transplantation with a glucocorticoid-free immunosuppressive agent in 2000 and achieved great success; since then, islet transplantation has been increasingly regarded as a promising strategy for the curative treatment of T1DM. However, many unavoidable challenges, such as a lack of donors, poor revascularization, blood-mediated inflammatory reactions, hypoxia, and side effects caused by immunosuppression have severely hindered the widespread application of islet transplantation in clinics. Biomaterial-based encapsulation and delivery strategies are proposed for overcoming these obstacles, and have demonstrated remarkable improvements in islet transplantation outcomes. Herein, the major problems faced by islet transplantation are summarized and updated biomaterial-based strategies for islet transplantation, including islet encapsulation across different scales, delivery of stem cell-derived beta cells, co-delivery of islets with accessory cells and immunomodulatory molecules are highlighted.

Patients with Obstructive Sleep Apnea Have Altered Levels of Four Cytokines Associated with Cardiovascular and Kidney Disease, but Near Normal Levels with Airways Therapy

INTRODUCTION

Obstructive sleep apnea (OSA) results in chronic intermittent hypoxia leading to systemic inflammation, increases in pro-inflammatory cytokines TNF-Alpha and IL-6, and increased risk for a number of life threatening medical disorders such as cardiovascular and kidney disease.

METHODS

A BioPlex Array was used to examined the serum levels of four cytokines also expressed in endothelial cells and/or macrophages and associated with cardiovascular and kidney disease risk.

RESULTS

Relative to untreated OSA patients, airways treated OSA patients had a 5.4-fold higher median level of MMP2 (p = 9.1x10-11), a 1.4-fold higher level of TWEAK (p = 1.8x10-7), a 1.7-fold higher level of CD163 (p = 1.4x10-6), but a 2.0-fold lower level of MMP3 (p = 7.9x10-7). Airway treatment resulted in levels more similar to or indistinguishable from control subjects. Both t-SNE or UMAP analysis of the global structure of these multi-dimensional data revealed two data clusters, one populated primarily with data for controls and most airways treated OSA patients and a second populated primarily with data for OSA patients.

DISCUSSION

We discuss a concept in which the aberrant levels of these cytokines in untreated OSA patients may represent a chronic response after years of experiencing intermittent nightly hypoxia, which attenuated the acute response to hypoxia. A balanced therapeutic correction of the aberrant levels of these cytokines may limit the progression of CVD and kidney disease in OSA patients.

Strategies to Potentiate Paracrine Therapeutic Efficacy of Mesenchymal Stem Cells in Inflammatory Diseases

Mesenchymal stem cells (MSCs) have been developed as cell therapeutics for various immune disorders using their immunoregulatory properties mainly exerted by their paracrine functions. However, variation among cells from different donors, as well as rapid clearance after transplantation have impaired the uniform efficacy of MSCs and limited their application. Recently, several strategies to overcome this limitation have been suggested and proven in pre-clinical settings. Therefore, in this review article, we will update the knowledge on bioengineering strategies to improve the immunomodulatory functions of MSCs, including genetic modification and physical engineering.

Challenges and advances in clinical applications of mesenchymal stromal cells

Mesenchymal stromal cells (MSCs), also known as mesenchymal stem cells, have been intensely investigated for clinical applications within the last decades. However, the majority of registered clinical trials applying MSC therapy for diverse human diseases have fallen short of expectations, despite the encouraging pre-clinical outcomes in varied animal disease models. This can be attributable to inconsistent criteria for MSCs identity across studies and their inherited heterogeneity. Nowadays, with the emergence of advanced biological techniques and substantial improvements in bio-engineered materials, strategies have been developed to overcome clinical challenges in MSC application. Here in this review, we will discuss the major challenges of MSC therapies in clinical application, the factors impacting the diversity of MSCs, the potential approaches that modify MSC products with the highest therapeutic potential, and finally the usage of MSCs for COVID-19 pandemic disease.

The role of the immune system in tendon healing: a systematic review

INTRODUCTION

The role of the immune system in tendon healing relies on polymorphonucleocytes, mast cells, macrophages and lymphocytes, the 'immune cells' and their cytokine production. This systematic review reports how the immune system affects tendon healing.

SOURCES OF DATA

We registered our protocol (registration number: CRD42019141838). After searching PubMed, Embase and Cochrane Library databases, we included studies of any level of evidence published in peer-reviewed journals reporting clinical or preclinical results. The PRISMA guidelines were applied, and risk of bias and the methodological quality of the included studies were assessed. We excluded all the articles with high risk of bias and/or low quality after the assessment. We included 62 articles assessed as medium or high quality.

AREAS OF AGREEMENT

Macrophages are major actors in the promotion of proper wound healing as well as the resolution of inflammation in response to pathogenic challenge or tissue damage. The immune cells secrete cytokines involving both pro-inflammatory and anti-inflammatory factors which could affect both healing and macrophage polarization.

AREAS OF CONTROVERSY

The role of lymphocytes, mast cells and polymorphonucleocytes is still inconclusive.

GROWING POINTS

The immune system is a major actor in the complex mechanism behind the healing response occurring in tendons after an injury. A dysregulation of the immune response can ultimately lead to a failed healing response.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further studies are needed to shed light on therapeutic targets to improve tendon healing and in managing new way to balance immune response.

Improving Cell Therapy Survival and Anabolism in Harsh Musculoskeletal Disease Environments

Cell therapies are an up and coming technology in orthopedic medicine that has the potential to provide regenerative treatments for musculoskeletal disease. Despite numerous cell therapies showing preclinical success for common musculoskeletal indications of disc degeneration and osteoarthritis, there have been mixed results when testing these therapies in humans during clinical trials. A theory behind the mixed success of these cell therapies is that the harsh microenvironments of the disc and knee they are entering inhibit their anabolism and survival. Therefore, there is much ongoing research looking into how to improve the survival and anabolism of cell therapies within these musculoskeletal disease environments. This includes research into improving cell function under specific microenvironmental conditions known to exist in the intervertebral disc (IVD) and knee environment such as hypoxia, low-nutrient conditions, hyperosmolarity, acidity, and inflammation. This research also includes improving differentiation of cells into desired native cell phenotypes to better enhance their survival and anabolism in the knee and IVD. This review highlights the effects of specific musculoskeletal microenvironmental challenges on cell therapies and what research is being done to overcome these challenges. Impact statement While there has been significant clinical interest in using cell therapies for musculoskeletal pathologies in the knee and intervertebral disc, cell therapy clinical trials have had mixed outcomes. The information presented in this review includes the environmental challenges (i.e., acidic pH, inflammation, hyperosmolarity, hypoxia, and low nutrition) that cell therapies experience in these pathological musculoskeletal environments. This review summarizes studies that describe various approaches to improving the therapeutic capability of cell therapies in these harsh environments. The result is an overview of what approaches can be targeted and/or combined to develop a more consistent cell therapy for musculoskeletal pathologies.

Safety and Localization of Mesenchymal Stromal Cells Derived from Human Adipose Tissue-Associated Hyaluronic Acid: A Preclinical Study

Millions of plastic surgeries are performed worldwide every year with the objective of correcting lipodystrophies stemming from lesions, tumor resections, birth defects, and AIDS-associated antiretroviral therapy. Besides that, a large number of clinical research have assessed the outcome of procedures that rely on combinations of dermal fillers and autologous cells. However, little is known about the safety of these combinations and the localization of the injected cells. The aim of this study was to test the toxicity of a solution containing 1% hyaluronic acid (HA) and adipose-derived stromal cells (ASCs) from the human adipose tissue and to assess the localization of the injected cells, with and without HA, labeled with technetium-99m. Rats received subcutaneous and intraperitoneal injections of a solution containing 1% HA/adipose-derived stromal cells isolated from the human fat tissue. The animals were then observed for up to forty-two days. The solution tested in this study did not result in systemic, biochemical, or anatomic alterations that could represent toxicity symptoms. The association of HA and ASCs labeled with technetium-99m remained at the site of the injection within a period of twenty-four hours, as demonstrated by a whole-body imaging software fusion of SPECT and CT. In conclusion, our study shows that the subcutaneous and intraperitoneal injection of HA associated with adipose-derived stromal cells (ASCs) is safe. The association of HA and ASCs did not induce local or systemic toxicity. Thus, the administration of volume equal to or less than 0.2 mL of the agent filler (1 × 10⁶ ASC+HA 1%) should be considered for subsequent studies and may be an alternative to dermal fillers due to the expected lasting effects.

Harnessing the Properties of Biomaterial to Enhance the Immunomodulation of Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have great therapeutic potential for tissue engineering and regenerative medicine due to their multipotency and paracrine functions. However, shortly after in vivo implantation, MSCs tend to migrate to the lungs and undergo apoptosis, which impairs their clinical efficacy. In addition, the ex vivo two-dimensional expansion of MSCs results in changes in their immunophenotype and functional activities compared to those in vivo. The use of biomaterials to culture and deliver MSCs has the potential to overcome these limitations. MSC-biomaterial constructs retain MSCs in situ and prolong their survival, while the MSCs ameliorate the foreign body reaction and fibrosis caused by the biomaterial. Biomaterial scaffolds can both preserve the tissue architecture and provide a three-dimensional biomimetic milieu for embedded MSCs, which enhance their paracrine functions, including their immunomodulatory potential. The dimensionality, physical characteristics, topographical cues, biochemistry, and microstructure can enhance the immunomodulatory potential of MSCs. Here, we review the link between the properties of biomaterial and the immunomodulatory potential of MSCs. Impact Statement Regeneration of cells, tissues, and whole organs is challenging. Mesenchymal stem cells (MSCs) have therapeutic potential in tissue engineering and regenerative medicine due to their paracrine functions, including immunomodulatory activity. The dimensionality, physical characteristics, topographical cues, biochemistry, and microstructure of biomaterial can be harnessed to enhance the immunomodulatory potential of MSCs for tissue engineering, which will increase their clinical efficacy, particularly for immune-related diseases.

High and Low Molecular Weight Hyaluronic Acid Differentially Influences Oxylipins Synthesis in Course of Neuroinflammation

Hyaluronic acid (HA), a major glycosaminoglycan of the extracellular matrix, has cell signaling functions that are dependent on its molecular weight. Anti-inflammatory effects for high-molecular-weight (HMW) HA and pro-inflammatory effects for low-molecular-weight (LMW) HA effects were found for various myeloid cells, including microglia. Astrocytes are cells of ectodermal origin that play a pivotal role in brain inflammation, but the link between HA with different molecular weights and an inflammatory response in these cells is not clear. We tested the effects of LMW and HMW HA in rat primary astrocytes, stimulated with Poly:IC (PIC, TLR3 agonist) and lipopolysaccharide (LPS, TLR4 agonist). Oxylipin profiles were measured by the UPLC-MS/MS analysis and metabolites HDoHEs (from docosahexaenoic acid), -HETEs, prostaglandins (from arachidonic acid), DiHOMEs and HODEs (from linoleic acid) were detected. Both, HMW and LMW HA downregulated the cyclooxygenase-mediated polyunsaturated fatty acids metabolism, LMW also reduced lipoxygenase-mediated fatty acid metabolism. Taken together, the data show that both LMW and HMW (i) influence themselves on cytokines (TNFα, IL-6, IL-10), enzymes iNOS, COX-2, and oxylipin levels in extracellular medium of cultured astrocytes, (ii) induced cellular adaptations in long-term applications, (iii) modulate TLR4- and TLR3-signaling pathways. The effects of HMW and LMW HA are predominantly revealed in TLR4– and TLR3- mediated responses, respectively.

Membrane Cholesterol Efflux Drives Tumor-Associated Macrophage Reprogramming and Tumor Progression

Macrophages possess intrinsic tumoricidal activity, yet tumor-associated macrophages (TAMs) rapidly adopt an alternative phenotype within the tumor microenvironment that is marked by tumor-promoting immunosuppressive and trophic functions. The mechanisms that promote such TAM polarization remain poorly understood, but once identified, they may represent important therapeutic targets to block the tumor-promoting functions of TAMs and restore their anti-tumor potential. Here, we have characterized TAMs in a mouse model of metastatic ovarian cancer. We show that ovarian cancer cells promote membrane-cholesterol efflux and depletion of lipid rafts from macrophages. Increased cholesterol efflux promoted IL-4-mediated reprogramming, including inhibition of IFNγ-induced gene expression. Genetic deletion of ABC transporters, which mediate cholesterol efflux, reverts the tumor-promoting functions of TAMs and reduces tumor progression. These studies reveal an unexpected role for membrane-cholesterol efflux in driving TAM-mediated tumor progression while pointing to a potentially novel anti-tumor therapeutic strategy.

Extracellular Vesicle-Educated Macrophages Promote Early Achilles Tendon Healing

Tendon healing follows a complex series of coordinated events, which ultimately produces a mechanically inferior tissue more scar‐like than native tendon. More regenerative healing occurs when anti‐inflammatory M2 macrophages play a more dominant role. Mesenchymal stromal/stem cells (MSCs) are able to polarize macrophages to an M2 immunophenotype via paracrine mechanisms. We previously reported that coculture of CD14+ macrophages (MQs) with MSCs resulted in a unique M2‐like macrophage. More recently, we generated M2‐like macrophages using only extracellular vesicles (EVs) isolated from MSCs creating “EV‐educated macrophages” (also called exosome‐educated macrophages [EEMs]), thereby foregoing direct use of MSCs. For the current study, we hypothesized that cell therapy with EEMs would improve in vivo tendon healing by modulating tissue inflammation and endogenous macrophage immunophenotypes. We evaluated effects of EEMs using a mouse Achilles tendon rupture model and compared results to normal tendon healing (without any biologic intervention), MSCs, MQs, or EVs. We found that exogenous administration of EEMs directly into the wound promoted a healing response that was significantly more functional and more regenerative. Injured tendons treated with exogenous EEMs exhibited (a) improved mechanical properties, (b) reduced inflammation, and (c) earlier angiogenesis. Treatment with MSC‐derived EVs alone were less effective functionally but stimulated a biological response as evidenced by an increased number of endothelial cells and decreased M1/M2 ratio. Because of their regenerative and immunomodulatory effects, EEM treament could provide a novel strategy to promote wound healing in this and various other musculoskeletal injuries or pathologies where inflammation and inadequate healing is problematic. Stem Cells2019;37:652–662

Antinociceptive effects of hyaluronic acid on monoiodoacetate-induced ankle osteoarthritis in rats

Purpose

Ankle osteoarthritis (OA) causes significant pain and debilitation; yet, its underlying mechanisms remain unclear. Clinically, hyaluronic acid (HA) is widely used to treat OA. The present study aimed to investigate the roles of HA in pain-related behavior, joint function, swelling, and pathological changes in cartilage in a rat model of monoiodoacetate (MIA)-induced ankle OA.

Materials and methods

Male Sprague Dawley rats were assigned to three experimental groups as follows: 1) MIA rats injected with 1 mg MIA in the right tibiotarsal joint for two consecutive days; 2) sham rats injected with saline instead of MIA; and 3) MIA-HA rats injected with HA in the tibiotarsal joint at 7, 14, and 21 days after MIA injection. Joint swelling, range of motion (ROM), and pain-related behavior were evaluated 1 day before and on the 7th, 14th, 21st, and 28th day after MIA or saline injection. Pathological changes in the ankle joint were assessed 28 days after MIA or saline injection.

Results

No significant difference in the degree of ankle swelling or ROM reduction was observed between MIA rats and MIA-HA rats. However, compared with those in MIA rats, mechanical and thermal hypersensitivity was significantly reduced and stride length significantly improved in MIA-HA rats. Histologic analysis revealed that cartilage degeneration was significantly suppressed in MIA-HA rats compared with that in MIA rats, reflecting the chondroprotective effects of HA.

Conclusion

HA improved pain-related behavior and stride length and suppressed MIA-induced cartilage degeneration. HA may thus inhibit OA progression and suppress peripheral and/or central sensitization.

The efficacy of multiple versus single hyaluronic acid injections: a systematic review and meta-analysis

BACKGROUND

Intra-articular hyaluronic acid (IA-HA) is a common therapy used to treat knee pain and suppress knee inflammation in knee osteoarthritis (OA), typically prescribed in regimens ranging from a single injection to 5 weekly injections given once weekly. We conducted a systematic review to determine the efficacy of IA-HA, with subgroup analyses to explore the differences in knee pain and adverse events (AEs) across different dosing regimens.

METHODS

We conducted a systematic search of the literature to identify studies evaluating IA-HA for the management of knee OA compared to IA-saline. Primary outcome measure was the mean knee pain score at 13 Weeks (3 months) or 26 weeks (6 months). Secondary outcome was the number of treatment-related AEs and treatment-related serious adverse events (SAEs). We evaluated differences in levels of pain and AEs/SAEs between dosing regimens compared to IA-Saline.

RESULTS

Thirty articles were included. Overall, IA-HA injections were associated with less knee pain compared to IA-Saline injections for all dosing regimens. 2-4 injections of IA-HA vs. IA-Saline produced the largest effect size at both 3-months and 6-months (Standard mean difference [SMD] = -0.76; -0.98 to -0.53, 95% CI, P < 0.00001, and SMD = -0.36; -0.63 to -0.09 95% CI, P = 0.008, respectively). Additionally, single injection studies yielded a non-significant treatment effect at 3 and 6 months, while ≥5 5 injections demonstrated a significant improvement in pain only at 6 months. Five or more injections of IA-HA were associated with a higher risk of treatment-related AEs compared to IA-Saline (Risk ratio [RR] = 1.67; 1.09 to 2.56 95% CI, p = 0.02), which was a result not seen within the 1 and 2-4 injection subgroups.

CONCLUSION

Overall, 2-4 and ≥5 injection regimens provided pain relief over IA-Saline, while single injection did not. Intra-articular injections of HA used in a 2-4 injection treatment regimen provided the greatest benefit when compared to IA-Saline with respect to pain improvement in patients with knee OA, and was generally deemed safe with few to no treatment-related AEs reported across studies. Future research is needed to directly compare these treatment regimens.

Autologous Bone Marrow Concentrate in a Sheep Model of Osteoarthritis: New Perspectives for Cartilage and Meniscus Repair

INTRODUCTION

Cell-based therapies are becoming a valuable tool to treat osteoarthritis (OA). This study investigated and compared the regenerative potential of bone marrow concentrate (BMC) and mesenchymal stem cells (MSC), both engineered with Hyaff(®)-11 (HA) for OA treatment in a sheep model.

METHODS

OA was induced via unilateral medial meniscectomy. Bone marrow was aspirated from the iliac crest, followed by concentration processes or cell isolation and expansion to obtain BMC and MSC, respectively. Treatments consisted of autologous BMC and MSC seeded onto HA. The regenerative potential of bone, cartilage, menisci, and synovia was monitored using macroscopy, histology, immunohistochemistry, and micro-computed tomography at 12 weeks post-op. Data were analyzed using the general linear model with adjusted Sidak's multiple comparison and Spearman's tests.

RESULTS

BMC-HA treatment showed a greater repair ability in inhibiting OA progression compared to MSC-HA, leading to a reduction of inflammation in cartilage, meniscus, and synovium. Indeed, the decrease of inflammation positively contributed to counteract the progression of fibrotic and hypertrophic processes, known to be involved in tissue failure. Moreover, the treatment with BMC-HA showed the best results in allowing meniscus regeneration. Minor healing effects were noticed at bone level for both cell strategies; however, a downregulation of subchondral bone thickness (Cs.Th) was found in both cell treatments compared to the OA group in the femur.

CONCLUSION

The transplantation of BMC-HA provided the best effects in supporting regenerative processes in cartilage, meniscus, and synovium and at less extent in bone. On the whole, both MSC and BMC combined with HA reduced inflammation and contributed to switch off fibrotic and hypertrophic processes. The observed regenerative potential by BMC-HA on meniscus could open new perspectives, suggesting its use not only for OA care but also for the treatment of meniscal lesions, even if further analyses are necessary to confirm its healing potential at long-term follow-up.

[Effect of injectable composites of calcium sulfate and hyaluronate in enhancing osteogenesis]

Objective

To fabricate an injectable composite bone substitute with hyaluronic acid (HA) and calcium sulfate and to evaluate the biocompatibility and effect of the composite on cell proliferation, osteogenic differentiation in vitro and osteogenic capability in vivo.

Methods

Calcium sulfate powder was mixed with HA solution, cross-linked HA solution, and phosphate buffer solution (PBS) in a ratio of 2∶1 ( W/ V) to get composites of CA+HA, CA+HAC, and CA. The standard extracts from above 3 materials were prepared according to ISO10993-5, and were used to culture mouse MC3T3-E1 cells. The composite biocompatibility and cell proliferation in different concentrations of extract were tested with cell counting kit-8 (CCK-8). The cells were cultured with standard medium as a control. The optimal concentration was selected for osteogenic differentiation test, and ELISA Kit was used to determine the alkaline phosphatase (ALP), collagen type I (COL-I), and osteocalcin (OCN). The femoral condylar bone defect was made on New Zealand white rabbits and repaired with CA+HA, CA+HAC, and CA. Micro-CT was done to evaluate new bone formation with bone volume/tissue volume (BV/TV) ratio at 6 and 12 weeks. HE staining was used to observe bone formation.

Results

CA+HA and CA+HAC were better in injectability and stability in PBS than CA. The biocompatibility test showed that absorbance ( A) value of CA group was significantly lower than that of control group ( P<0.05) at 6, 12, and 24 hours after culture, but no significant difference was found in A values between CA+HA group or CA+HAC group and control group ( P>0.05). The proliferation test showed 25% and 50% extract of all 3 materials had significantly higher A value than control group ( P<0.05). For 75% and 100% extract, only CA+HA group had significantly higher A value than control group ( P<0.05). And 50% extract was selected for osteogenic differentiation test. At 14 and 21 days, ALP, COL-I and OCN concentrations of CA+HA group and CA+HAC group were significantly higher than those of CA group and control group ( P<0.05). Micro-CT results showed higher BV/TV in CA+HA group and CA+HAC group than CA group at 6 and 12 weeks ( P<0.05), but no significant difference was found between CA+HA group and CA+HAC group ( P>0.05). HE staining revealed that a little bone tissue was seen in CA+HA group and CA+HAC group, but there was no bone formation in CA group at 6 weeks; more streak bone tissue in CA+HA group and CA+HAC group than CA group at 12 weeks.

Conclusion

Composites prepared with calcium sulfate and HA or with cross-linked HA are stable, injectable, and biocompatible. The materials have excellent effect on proliferation and differentiation of mouse MC3T3-E1 cells. They also show good osteogenic capability in vivo. So it is a potential bone substitutes for bone defective diseases.

Stage-specific differences in secretory profile of mesenchymal stromal cells (MSCs) subjected to early- vs late-stage OA synovial fluid

OBJECTIVE

Although, mesenchymal stromal cells (MSCs) are being clinically investigated for their use in osteoarthritis (OA), it is unclear whether their postulated therapeutic properties are equally effective in the early- and late-stages of OA. In this study we investigated MSC cytokine secretion post-exposure to synovial fluid (SF), obtained from early- vs late-stage knee OA patients to justify a potential patient stratification strategy to maximize MSC-mediated treatment effects.

METHOD

Subjects were recruited and categorized into early- [Kellgren-Lawrence (KL) grade I/II, n = 12] and late-stage (KL-III/IV, n = 12) knee OA groups. SF samples were obtained, and their proteome was tested using multiplex assays, after 3-days culture, with and without MSCs. SFs cultured without MSCs were used as a baseline to identify MSC-secreted factors into SFs cultured with MSCs. Linear mixed-effect models and non-parametric tests were used to identify alterations in the MSC secretome during exposure to OA SF (3-days). MSCs cultured for 3-days in 0.5% fetal bovine serum (FBS)-supplemented medium were used to compare SF results with culture medium.

RESULTS

Following exposure to OA SF, the MSC secretome contained proteins that are involved in tissue repair, angiogenesis, chemotaxis, matrix remodeling and the clotting process. However, chemokine (C-X-C motif) ligand-8 (CXCL8; chemoattractant), interleukin-6 (IL6) and chemokine (C-C motif) ligand 2 (CCL2) were elevated in the MSC-secretome in response to early- vs late-stage OA SF.

CONCLUSION

Early- vs late-stage OA SF samples elicit a differential MSC secretome response, arguing for stratification of OA patients to maximize MSC-mediated therapeutic effects.