Cell-based Treatment Research Articles

Adipose-derived stem cell exosome NFIC improves diabetic foot ulcers by regulating miR-204-3p/HIPK2

BackgroundDiabetic foot ulcers (DFU) are a serious complication of diabetes that lead to significant morbidity and mortality. Recent studies reported that exosomes secreted by human adipose tissue-derived mesenchymal stem cells (ADSCs) might alleviate DFU development. However, the molecular mechanism of ADSCs-derived exosomes in DFU is far from being addressed.MethodsHuman umbilical vein endothelial cells (HUVECs) were induced by high-glucose (HG), which were treated with exosomes derived from nuclear factor I/C (NFIC)-modified ADSCs. MicroRNA-204-3p (miR-204-3p), homeodomain-interacting protein kinase 2 (HIPK2), and NFIC were determined using real-time quantitative polymerase chain reaction. Cell proliferation, apoptosis, migration, and angiogenesis were assessed using cell counting kit-8, 5-ethynyl-2′-deoxyuridine (EdU), flow cytometry, wound healing, and tube formation assays. Binding between miR-204-3p and NFIC or HIPK2 was predicted using bioinformatics tools and validated using a dual-luciferase reporter assay. HIPK2, NFIC, CD81, and CD63 protein levels were measured using western blot. Exosomes were identified by a transmission electron microscope and nanoparticle tracking analysis.ResultsmiR-204-3p and NFIC were reduced, and HIPK2 was enhanced in DFU patients and HG-treated HUVECs. miR-204-3p overexpression might abolish HG-mediated HUVEC proliferation, apoptosis, migration, and angiogenesis in vitro. Furthermore, HIPK2 acted as a target of miR-204-3p. Meanwhile, NFIC was an upstream transcription factor that might bind to the miR-204-3p promoter and improve its expression. NFIC-exosome from ADSCs might regulate HG-triggered HUVEC injury through miR-204-3p-dependent inhibition of HIPK2.ConclusionExosomal NFIC silencing-loaded ADSC sheet modulates miR-204-3p/HIPK2 axis to suppress HG-induced HUVEC proliferation, migration, and angiogenesis, providing a stem cell-based treatment strategy for DFU.

A Comprehensive Review on Neuroimmunology: Insights from Multiple Sclerosis to Future Therapeutic Developments.

This review delves into neuroimmunology, focusing on its relevance to multiple sclerosis (MS) and potential treatment advancements. Neuroimmunology explores the intricate relationship between the immune system and the central nervous system (CNS). Understanding these mechanisms is vital for grasping the pathophysiology of diseases like MS and for devising innovative treatments. This review introduces foundational neuroimmunology concepts, emphasizing the role of immune cells, cytokines, and blood-brain barrier in CNS stability. It highlights how their dysregulation can contribute to MS and discusses genetic and environmental factors influencing MS susceptibility. Cutting-edge research methods, from omics techniques to advanced imaging, have revolutionized our understanding of MS, offering valuable diagnostic and prognostic tools. This review also touches on the intriguing gut-brain axis, examining how gut microbiota impacts neuroimmunological processes and its potential therapeutic implications. Current MS treatments, from immunomodulatory drugs to disease-modifying therapies, are discussed alongside promising experimental approaches. The potential of personalized medicine, cell-based treatments, and gene therapy in MS management is also explored. In conclusion, this review underscores neuroimmunology's significance in MS research, suggesting that a deeper understanding could pave the way for more tailored and effective treatments for MS and similar conditions. Continued research and collaboration in neuroimmunology are essential for enhancing patient outcomes.

Artificial intelligence and improvement of stem cell delivery in healthcare

Artificial intelligence (AI) is critical for improving the quality of stem cell manufacturing and delivery. AI can assist in determining the viability, effectiveness, efficacy, and safety of stem cells. Furthermore, in stem cell and regenerative medicine, AI is utilized to streamline simulation and model-building processes and find connections between cellular activities and their microenvironments. However, thoughtful consideration is required to minimize unwanted implications of AI incorporation for stem cell-based treatment.

In Vivo Stem Cell Imaging Principles and Applications.

Stem cells are the foundational cells for every organ and tissue in our body. Cell-based therapeutics using stem cells in regenerative medicine have received attracting attention as a possible treatment for various diseases caused by congenital defects. Stem cells such as induced pluripotent stem cells (iPSCs) as well as embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), and neuroprogenitors stem cells (NSCs) have recently been studied in various ways as a cell-based therapeutic agent. When various stem cells are transplanted into a living body, they can differentiate and perform complex functions. For stem cell transplantation, it is essential to determine the suitability of the stem cell-based treatment by evaluating the origin of stem, the route of administration, in vivo bio-distribution, transplanted cell survival, function, and mobility. Currently, these various stem cells are being imaged in vivo through various molecular imaging methods. Various imaging modalities such as optical imaging, magnetic resonance imaging (MRI), ultrasound (US), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) have been introduced for the application of various stem cell imaging. In this review, we discuss the principles and recent advances of in vivo molecular imaging for application of stem cell research.

Cell-Based Outer Vocal Fold Replacement Both Treats and Prevents Vocal Fold Scarring in Rabbits.

Numerous pharmacological and cell-based treatments have shown promise in preventing vocal fold (VF) scarring when applied at the time of injury. A common clinical scenario, however, is the finding of mature scar impeding voicing. Many treatments are less effective in remodeling existing scar tissue. This objective of this study is to determine if a cell-based outer vocal fold replacement (COVR) effectively restores VF function when applied to existing scar. Eighteen rabbits were allocated to three groups: unilateral COVR implant at the time of cordectomy (acute COVR); unilateral cordectomy followed by COVR implant 2 months later (chronic COVR); and unilateral cordectomy followed by sham implant surgery 2 months later (chronic scar). Larynges were harvested 2 months after implant or sham surgery. All larynges in the COVR groups demonstrated human leukocyte antigen labeling on immunohistochemistry (IHC). COVR groups had increased hyaluronic acid content compared with normal. VF stiffness as measured by elastic moduli in acute COVR and chronic COVR were similar to their contralateral unoperated VF. COVR implantation in both acutely injured and chronically scarred VF demonstrate persistence of implanted cells, restored tissue biomechanics, and increased hyaluronic acid content. NA Laryngoscope, 134:764-772, 2024.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: An Emerging Diagnostic and Therapeutic Biomolecules for Neurodegenerative Disabilities.

Mesenchymal stem cells (MSCs) are a type of versatile adult stem cells present in various organs. These cells give rise to extracellular vesicles (EVs) containing a diverse array of biologically active elements, making them a promising approach for therapeutics and diagnostics. This article examines the potential therapeutic applications of MSC-derived EVs in addressing neurodegenerative disorders such as Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). Furthermore, the present state-of-the-art for MSC-EV-based therapy in AD, HD, PD, ALS, and MS is discussed. Significant progress has been made in understanding the etiology and potential treatments for a range of neurodegenerative diseases (NDs) over the last few decades. The contents of EVs are carried across cells for intercellular contact, which often results in the control of the recipient cell's homeostasis. Since EVs represent the therapeutically beneficial cargo of parent cells and are devoid of many ethical problems connected with cell-based treatments, they offer a viable cell-free therapy alternative for tissue regeneration and repair. Developing innovative EV-dependent medicines has proven difficult due to the lack of standardized procedures in EV extraction processes as well as their pharmacological characteristics and mechanisms of action. However, recent biotechnology and engineering research has greatly enhanced the content and applicability of MSC-EVs.

CDK6 is essential for mesenchymal stem cell proliferation and adipocyte differentiation.

Background: Overweight or obesity poses a significant risk of many obesity-related metabolic diseases. Among all the potential new therapies, stem cell-based treatments hold great promise for treating many obesity-related metabolic diseases. However, the mechanisms regulating adipocyte stem cells/progenitors (precursors) are unknown. The aim of this study is to investigate if CDK6 is required for mesenchymal stem cell proliferation and adipocyte differentiation. Methods: Cyclin-dependent kinase 6 (Cdk6) mouse models together with stem cells derived from stromal vascular fraction (SVF) or mouse embryonic fibroblasts (MEFs) of Cdk6 mutant mice were used to determine if CDK6 is required for mesenchymal stem cell proliferation and adipocyte differentiation. Results: We found that mice with a kinase inactive CDK6 mutants (K43M) had fewer precursor residents in the SVF of adult white adipose tissue (WAT). Stem cells from the SVF or MEFs of K43M mice had defects in proliferation and differentiation into the functional fat cells. In contrast, mice with a constitutively active kinase CDK6 mutant (R31C) had the opposite traits. Ablation of RUNX1 in both mature and precursor K43M cells, reversed the phenotypes. Conclusion: These results represent a novel role of CDK6 in regulating precursor numbers, proliferation, and differentiation, suggesting a potential pharmacological intervention for using CDK6 inhibitors in the treatment of obesity-related metabolic diseases.

Knowledge about stem cell sources and obstacles in donation of bone marrow and peripheral blood stem cells: a cross-sectional survey from Ha’il city to track the prospects of regenerative medicine in Saudi Arabia

BackgroundPromoting stem cell donation behaviors could be crucial in advancing stem cell-based treatment, research and improving public health in Saudi Arabia. Donation of stem cells can be considered an act of social welfare just like blood donation because stem-cell-based therapies are emerging as a hope for those suffering from chronic health conditions and/or terminal illnesses.AimThis study aims at assessing levels of awareness about sources of stem-cells, donor organizations and predictors of stem cell donation behavior in target population.MethodsThe study employed a cross-sectional online survey method. The study sample comprises 1325 educated Saudi people living in Ha’il city. The survey questionnaire collected data about respondents’ demographic background, awareness about various sources of stem cells and stem-cell donor registries, willingness to donate stem cells, registration status and obstacles in stem cell donation registration. Percentages, Chi-square analysis and Odd Ratios were computed to analyze the data.ResultsIn this sample, (n = 696; 52%) were males and (n = 629; 48%) were females. Although (n = 1308; 98%) percent of respondents reported willingness to donate stem cell, less than one percent (n = 6; 0.5) were registered with Saudi Stem Cell Registry. Over 50% of respondents hold inaccurate perceptions about sources of stem cell. Odd Ratio (OR) values from binary logistic regression model identified four factors as significant predictors of non-registration status. These included (i) unaware about donor agencies and procedures (OR = 10.07; p < 0.05), (ii) unaware about possibility to donate stem cells (OR = 8.08; p < 0.05) (iii) concerns about impact on health (OR = 10.01; p < 0.05) and (iv) have health issues that does not permit donation (OR = 10.50; p < 0.05).ConclusionStem cell registrations can be enhanced through appropriate health education programs that focus on increasing awareness about donation procedures, trustworthy donor organizations and reducing people apprehensions related to donation.

Engineered biochemical cues of regenerative biomaterials to enhance endogenous stem/progenitor cells (ESPCs)-mediated articular cartilage repair.

As a highly specialized shock-absorbing connective tissue, articular cartilage (AC) has very limited self-repair capacity after traumatic injuries, posing a heavy socioeconomic burden. Common clinical therapies for small- to medium-size focal AC defects are well-developed endogenous repair and cell-based strategies, including microfracture, mosaicplasty, autologous chondrocyte implantation (ACI), and matrix-induced ACI (MACI). However, these treatments frequently result in mechanically inferior fibrocartilage, low cost-effectiveness, donor site morbidity, and short-term durability. It prompts an urgent need for innovative approaches to pattern a pro-regenerative microenvironment and yield hyaline-like cartilage with similar biomechanical and biochemical properties as healthy native AC. Acellular regenerative biomaterials can create a favorable local environment for AC repair without causing relevant regulatory and scientific concerns from cell-based treatments. A deeper understanding of the mechanism of endogenous cartilage healing is furthering the (bio)design and application of these scaffolds. Currently, the utilization of regenerative biomaterials to magnify the repairing effect of joint-resident endogenous stem/progenitor cells (ESPCs) presents an evolving improvement for cartilage repair. This review starts by briefly summarizing the current understanding of endogenous AC repair and the vital roles of ESPCs and chemoattractants for cartilage regeneration. Then several intrinsic hurdles for regenerative biomaterials-based AC repair are discussed. The recent advances in novel (bio)design and application regarding regenerative biomaterials with favorable biochemical cues to provide an instructive extracellular microenvironment and to guide the ESPCs (e.g. adhesion, migration, proliferation, differentiation, matrix production, and remodeling) for cartilage repair are summarized. Finally, this review outlines the future directions of engineering the next-generation regenerative biomaterials toward ultimate clinical translation.

Developments in Stem Cell Therapy by Utilizing Artificial Intelligence.

Undifferentiated cells, known as stem cells, have the capacity to self-renew and specialise in a variety of distinct mature and functional cell types while still retaining their original identity. For their significance in regenerative medicine, stem cells' deep potential has been widely examined, and this work has established the groundwork for cell-based therapeutics. With the potential to repair and restore specific organs or tissue injuries or chronic disease situations when the body's regenerative process is insufficient to heal, regenerative medicine is quickly advancing in healthcare. The most recent developments in stem cell-based treatments for regenerative medicine are covered in this review, focusing on mesenchymal stem cell-based treatments because these cells have received the most clinical research. The most recent applications of artificial intelligence algorithms in stem cell-based therapeutics are presented, along with their limitations and potential future applications.

Kartogenin-loaded hydrogel promotes intervertebral disc repair via protecting MSCs against reactive oxygen species microenvironment by Nrf2/TXNIP/NLRP3 axis.

Intervertebral disc (IVD) degeneration (IDD) and the consequent low back pain present a major medical challenge. Stem cell-based tissue engineering is promising for the treatment of IDD. However, stem cell-based treatment is severely impaired by the increased generation of reactive oxygen species (ROS) in degenerative disc, which can lead to a high level of cell dysfunction and even death. In this study, a kartogenin (KGN)@PLGA-GelMA/PRP composite hydrogel was designed and used as a carrier of ADSCs-based therapies in disc repair. Injectable composite hydrogel act as a carrier for controlled release of KGN and deliver ADSCs to the degenerative disc. The released KGN can stimulate the differentiation of ADSCs into a nucleus pulposus (NP) -like phenotype and boost antioxidant capacity of ADSCs via activating Nrf2/TXNIP/NLRP3 axis. Furthermore, the composite hydrogel combined with ADSCs attenuated the in vivo degeneration of rat IVDs, maintained IVD tissue integrity and accelerated the synthesis of NP-like extracellular matrix. Therefore, the KGN@PLGA-GelMA/PRP composite hydrogel is a promising strategy for stem cell-based therapies of IDD.

Decellularized tendon scaffolds loaded with collagen targeted extracellular vesicles from tendon-derived stem cells facilitate tendon regeneration

Stem cell-based treatment of tendon injuries remains to have some inherent issues. Extracellular vesicles derived from stem cells have shown promising achievements in tendon regeneration, though their retention in vivo is low. This study reports on the use of a collagen binding domain (CBD) to bind extracellular vesicles, obtained from tendon-derived stem cells (TDSCs), to collagen. CBD-extracellular vesicles (CBD-EVs) were coupled to decellularized bovine tendon sheets (DBTS) to fabricate a bio-functionalized scaffold (CBD-EVs-DBTS). Our results show that thus obtained bio-functionalized scaffolds facilitate the proliferation, migration and tenogenic differentiation of stem cells in vitro. Furthermore, the scaffolds promote endogenous stem cell recruitment to the defects, facilitate collagen deposition and improve the biomechanics of injured tendons, thus resulting in functional regeneration of tendons.

Report of a phase 1 clinical trial for safety assessment of human placental mesenchymal stem cells therapy in patients with critical limb ischemia (CLI)

BackgroundCritical limb ischemia (CLI) is associated with increased risk of tissue loss, leading to significant morbidity and mortality. Therapeutic angiogenesis using cell-based treatments, notably mesenchymal stem cells (MSCs), is essential for enhancing blood flow to ischemic areas in subjects suffering from CLI. The objective of this study was to evaluate the feasibility of using placenta-derived mesenchymal stem cells (P-MSCs) in patients with CLI.MethodsThis phase I dose-escalation study investigated P-MSCs in nine CLI patients who were enrolled into each of the two dosage groups (20 × 106 and 60 × 106 cells), delivered intramuscularly twice, two months apart. The incidence of treatment-related adverse events was the primary endpoint. The decrease in inflammatory cytokines, improvement in the ankle-brachial pressure index (ABI), maximum walking distance, vascular collateralization, alleviation of rest pain, healing of ulceration, and avoidance of major amputation in the target leg were the efficacy outcomes.ResultsAll dosages of P-MSCs, including the highest tested dose of 60 × 106 cells, were well tolerated. During the 6-month follow-up period, there was a statistically significant decrease in IL-1 and IFN-γ serum levels following P-MSC treatment. The blood lymphocyte profile of participants with CLI did not significantly differ, suggesting that the injection of allogeneic cells did not cause T-cell proliferation in vivo. We found clinically substantial improvement in rest pain, ulcer healing, and maximum walking distance after P-MSC implantation. In patients with CLI, we performed minor amputations rather than major amputations. Angiography was unable to demonstrate new small vessels formation significantly.ConclusionThe observations from this phase I clinical study indicate that intramuscular administration of P-MSCs is considered safe and well tolerated and may dramatically improve physical performance and minimize inflammatory conditions in patients with CLI.Trial registration: IRCT, IRCT20210221050446N1. Registered May 09, 2021.

Analyzing the Current Umbilical Cord-derived Mesenchymal Stem Cell Secretome Evidence for Erectile Dysfunction Management

Erectile dysfunction (ED) impacts millions of men, especially older men, and current treatment options, including tadalafil, phosphodiesterase type 5 inhibitors, and short-acting testosterone, are ineffective. This necessitates the immediate development of effective alternative ED treatments. In recent years, attention has been drawn to the secretome of umbilical cord-derived mesenchymal stem cells (UC-MSCs) due to its anti-inflammatory and immunomodulatory properties, which can reduce inflammation and promote tissue repair. The UC-MSCs secretome contains numerous growth factors, such as vascular endothelial growth factor, insulin-like growth factor 1 (IGF-1), and basic fibroblast growth factor (bFGF), which are essential for promoting endothelial cell proliferation and penile blood flow. This review seeks to examine the existing evidence on the use of stem cells, with a focus on UC-MSCs secretome, as a potential treatment modality for erectile dysfunction (ED). By reviewing the PubMed, Google Scholar, and Scopus databases, a comprehensive narrative review was conducted. Included among the search queries were "erectile dysfunction," "stem cells," "mesenchymal stem cells," "umbilical cord," and "secretome." Only research published in English within the past decade was included in the analysis. The findings indicate that the secretome of UC-MSCs has promise for treating ED. The secretome is composed of growth factors, cytokines, and other bioactive compounds that promote tissue repair and regeneration via paracrine effects on adjacent cells. The administration of UC-MSCs improved erectile function, penile blood flow, and smooth muscle content. In addition, discarded UC-MSCs serve as a cost-effective and copious source of ethically acceptable and immunogenic UC-MSCs with low immunogenicity. The secretome of UC-MSCs offers a potential therapeutic strategy for treating erectile dysfunction. However, further preclinical and clinical research must be done to determine the safety and efficacy of stem cell-based treatments for erectile dysfunction.

Poster 114: Viability and Expression of Chondrocytes Harvested During Arthroscopic Treatment of Femoroacetabular Impingement

Poster 114: Viability and Expression of Chondrocytes Harvested During Arthroscopic Treatment of Femoroacetabular Impingement

1808-PUB: Effective and Durable Stem-Cell-Enabled Therapy of Autoimmune T1DM in Rodents and Dogs Provides the Scientific Basis for the First-in-Human Trial Using I.P. Administered “Neo-Islets,” 3-D Organoids of Allogeneic Islet, and Mesenchymal Stromal Cells—The Omentum Becomes the New Endocrine Pancreas without the Need for Antirejection Drugs

Two initial reports from Clinical Trials with cell-based interventions for the urgently needed therapy of T1DM show: (a) Open, s.c.-placed encapsulation devices containing insulin-producing progenitor cells that require anti-rejection drugs have failed to adequately improve glycemic control. (b) The intraportal administration of stem cell-derived insulin-producing cells, requiring anti-rejection drugs, has shown promising results in 2 or 3 subjects. However, the inability to retrieve these cells and the need for anti-rejection drugs remain a concern. Our approach harnesses the immune-modulating and -isolating, anti-inflammatory, angiogenic, anti-apoptotic and other trophic actions of Mesenchymal Stromal Cells (MSCs). First, we demonstrated that allogeneic Neo-islets (NIs), islet-sized organoids composed of equal numbers of MSCs and culture expanded Islet Cells do, when given i.p., omentally engraft, redifferentiate, re-express all islet hormones and permanently restore euglycemia in auto-immune diabetic NOD mice, i.e., without encapsulation devices or antirejection drugs. The omentum becomes the new endocrine pancreas. Second, i.p. therapy of spontaneously diabetic pet dogs with allogeneic canine NIs significantly improved glycemia and insulin needs (&amp;gt; 3 years), and this without immune response (abstract this meeting). Third, human NIs permanently correct streptozotocin-induced diabetes in NOD/SCID mice. Removal of the omentally-engrafted NIs promptly restores the diabetic state. No long-term complications of the NI therapy have been observed. Based on this body of evidence, a successful Pre-IND meeting with the FDA was held and final Proof-of-Concept studies that are expected to lead IND approval are ongoing. Disclosure A.Gooch: Board Member; SymbioCellTech, LLC, Employee; SymbioCellTech, LLC, Stock/Shareholder; SymbioCellTech, LLC. C.Westenfelder: Board Member; SymbioCellTech, LLC., Employee; SymbioCellTech, LLC., Research Support; SymbioCellTech, LLC., Stock/Shareholder; SymbioCellTech, LLC.

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.

Failure of cartilage regeneration: emerging hypotheses and related therapeutic strategies.

Osteoarthritis (OA) is a disabling condition that affects billions of people worldwide and places a considerable burden on patients and on society owing to its prevalence and economic cost. As cartilage injuries are generally associated with the progressive onset of OA, robustly effective approaches for cartilage regeneration are necessary. Despite extensive research, technical development and clinical experimentation, no current surgery-based, material-based, cell-based or drug-based treatment can reliably restore the structure and function of hyaline cartilage. This paucity of effective treatment is partly caused by a lack of fundamental understanding of why articular cartilage fails to spontaneously regenerate. Thus, research studies that investigate the mechanisms behind the cartilage regeneration processes and the failure of these processes are critical to instruct decisions about patient treatment or to support the development of next-generation therapies for cartilage repair and OA prevention. This Review provides a synoptic and structured analysis of the current hypotheses about failure in cartilage regeneration, and the accompanying therapeutic strategies to overcome these hurdles, including some current or potential approaches to OA therapy.

Classic costimulatory interactions in MAIT cell responses: from gene expression to immune regulation.

Mucosa-associated invariant T (MAIT) cells are evolutionarily conserved, innate-like T lymphocytes with enormous immunomodulatory potentials. Due to their strategic localization, their invariant T cell receptor (iTCR) specificity for major histocompatibility complex-related protein 1 (MR1) ligands of commensal and pathogenic bacterial origin, and their sensitivity to infection-elicited cytokines, MAIT cells are best known for their antimicrobial characteristics. However, they are thought to also play important parts in the contexts of cancer, autoimmunity, vaccine-induced immunity, and tissue repair. While cognate MR1 ligands and cytokine cues govern MAIT cell maturation, polarization, and peripheral activation, other signal transduction pathways, including those mediated by costimulatory interactions, regulate MAIT cell responses. Activated MAIT cells exhibit cytolytic activities and secrete potent inflammatory cytokines of their own, thus transregulating the biological behaviors of several other cell types, including dendritic cells, macrophages, natural killer cells, conventional T cells, and B cells, with significant implications in health and disease. Therefore, an in-depth understanding of how costimulatory pathways control MAIT cell responses may introduce new targets for optimized MR1/MAIT cell-based interventions. Herein, we compare and contrast MAIT cells and mainstream T cells for their expression of classic costimulatory molecules belonging to the immunoglobulin superfamily and the tumor necrosis factor (TNF)/TNF receptor superfamily, based not only on the available literature but also on our transcriptomic analyses. We discuss how these molecules participate in MAIT cells' development and activities. Finally, we introduce several pressing questions vis-à-vis MAIT cell costimulation and offer new directions for future research in this area.

P41: 4D Manufacturing: Immunoprotective Materials for Islet Tissue Patches in Cell-Based Diabetes Treatments

Purpose: In order to cure diabetes on a large scale, researchers are working to develop insulin-producing cells differentiated from human pluripotent stem cells, encapsulating the tissues to protect the cells from immune attack, and implanting the cells for regulated insulin secretion. This project explored the synthesis and in vivo performance of a 4D biomaterial intended to protect implanted insulin-producing cells in the body. 3D printing of insulin-producing cells encapsulated within the biomaterial with additional timed-release anti-inflammatory agents enabled complex, personalized shapes and a 4D functional material. Methods: Anti-inflammatory agents were functionalized with varying permanent and degradable linkages to achieve a range of timed-release therapeutics to prevent immune system-mediated rejection. The molecules were crosslinked with a multi-arm polyethylene glycol (PEG) material in the subcutaneous space of immunocompetent C57BL/6 mice. After 30 days, tissue slices of the explant were examined using H&E staining revealing the thickness of biological encapsulation compared to alginate controls. Results: PEG-based implants with acetal linkages enabling the slow release (~30 days) of anti-inflammatory agents achieved the thinnest layer of biological encapsulation compared to the controls. Summary: Collectively, the described 4D biomaterial with other novel approaches and tools will enable the investigation of survival and function of a stem cell-based therapy for diabetes that could ultimately allow patients to live a diabetes-free lifestyle.