In Vitro Culture Expansion Shifts the Immune Phenotype of Human Adipose-Derived Mesenchymal Stem Cells

Phenotypic changes associated with continuous long term in vitro expansion of bone marrow-derived mesenchymal stem cells

In vitro expansion of mesenchymal stem cells is necessary to obtain a higher cell number for clinical applications. However, long-term expansion can produce significant phenotypic changes on these cells, decreasing their therapeutic utility. Therefore, understanding the phenotypic changes that long-term expansion triggers in mesenchymal stem cells will allow for better and more consistent cell therapy results. Here, we evaluate the phenotypic changes caused by continuous passaging through colony forming unit-fibroblast assay, senescence beta-galactosidase staining, morphology examination, secretome analysis, surface marker expression, protein quantification, osteogenic and adipogenic differentiation, and CD4+ T lymphocyte immunosuppressive potential. Long-term in vitro culture decreases mesenchymal stem cell osteogenic potential and self-renewal, increases cell size, and senescence, but does not consistently affect adipogenic differentiation. Surface marker expression remains similar for positive and negative markers, while secretory phenotype shifts with decreased p14ARF, MMP-3, p21 Waf1/Cip1,ENA-78, GCP-2, GROα, IL-3, IL-7, IL-8, RANTES, TNFβ, and VEGF-A expression, and increased p53, p16 INK4a, MCP-1, and SDF-1 expression. Immunomodulatory potential remains unchanged. These findings can help better understand the phenotypic changes that mesenchymal stem cells undergo while expanded in vitro.

Myogenic nano-adjuvant for orthopedic-related sarcopenia via mitochondrial homeostasis modulation in macrophage-myosatellite metabolic crosstalk

The decline in skeletal muscle mass and muscle strength linked to aging, also known as sarcopenia, is strongly associated with disability, traumatic injury, and metabolic disease in patients. Meanwhile, sarcopenia increases the risk of adverse orthopedic perioperative complications including implant dislocation, infection, loosening, and poor wound healing. Mitochondrial dyshomeostasis in the immune-myosatellite metabolic crosstalk is one of the major pathological factors in sarcopenia. To reduce the incidence of orthopedic perioperative complications in patients, we designed and developed a nano-adjuvant based on two-dimensional layer double hydroxide (LDH) for sustained improvement of systemic and orthopedic-related sarcopenia. Construction of MgAlCo-LDH@UA (MACL@UA) nano-adjuvant was performed by introducing cobalt in magnesium-aluminum LDH and further loading urolithin A (UA). The release of magnesium ions and UA promoted myocyte proliferation, angiogenesis and improved mitochondrial homeostasis. Al acted as an immunomodulatory adjuvant to enhance the metabolic crosstalk between macrophages and myosatellite cells, and prompted macrophage-derived glutamine nourishment. Animal experiments confirmed that vaccination with MACL@UA in systemic sarcopenia and intensive orthopedic perioperative vaccination with MACL@UA significantly enhanced quadriceps muscle mass in rats. This nano-adjuvant offers a solution for long-term improvement of sarcopenia and short-term significant reduction of orthopedic perioperative complications in patients, with promising prospects for clinical application and commercial translation.

Impacts of Inorganic Arsenic Exposure on Genetic Stability of Human Mesenchymal Stromal Cells

Human mesenchymal stem/stromal cells (hMSCs) can differentiate into mesoderm-type cells, making them suitable candidates for tissue repair therapies. However, their relatively low frequency in adult tissue necessitates ex vivo expansion prior to regenerative medicine applications, and therefore, long-term hMSC genetic stability during expansion should be studied. hMSC applications in regenerative medicine ensure commercial availability of normal karyotype human primary cells for toxicity assessment and hMSCs could serve as alternatives to immortalized human cell models. In this work, we evaluated the potential of hMSCs in toxicity testing using inorganic arsenic (iAs) as a case study. hMSCs were exposed to iAs at different durations to track cellular aging and study long-term genetic stability. iAs exposures (48 h) resulted in micronuclei induction. hMSCs were also exposed to iAs for 6 days to determine if hMSCs would become more susceptible to chromosomal damage following exposure to the model genotoxicant, mitomycin C (MMC). The culture duration and iAs exposure did not alter MMC potency, indicating that the hMSC susceptibility to chromosomal damage remained unchanged. We also used gene expression analysis to investigate the molecular impacts of iAs on hMSCs over the course of short (3 days total) and long (30 days total) experiments. Both iAs exposures activated biomarkers associated with oxidative stress, but not biomarkers for direct DNA damage, providing support for an indirect mode of action for iAs genotoxicity. Overall, this study establishes the utility of hMSCs as a new model for toxicity screening and provides mechanistic information underlying iAs toxicity.

Electrical Phenotyping of Aged Human Mesenchymal Stem Cells Using Dielectrophoresis

Human mesenchymal stem cells (hMSCs) are widely used in regenerative medicine, but large-scale in vitro expansion alters their function, impacting proliferation and differentiation potential. Currently, a predictive marker to assess these changes is lacking. Here, we used dielectrophoresis (DEP) to characterize the electrical phenotype of hMSCs derived from bone marrow (BM), adipose tissue (AT), and umbilical cord (UC) as they aged in vitro from passage 4 (P4) to passage 9 (P9). The electrical phenotype was defined by the DEP spectra, membrane capacitance, and cytoplasm conductivity. Cell morphology and size, growth characteristics, adipogenic differentiation potential, and osteogenic differentiation potential were assessed alongside label-free biomarker membrane capacitance and cytoplasm conductivity. Differentiation was confirmed by histological staining and RT-qPCR. All hMSCs exhibited typical morphology, though cell size varied, with UC-hMSCs displaying the largest variability across all size metrics. Growth analysis revealed that UC-hMSCs proliferated the fastest. The electrical phenotype varied with cell source and in vitro age, with high passage hMSCs showing noticeable shifts in DEP spectra, membrane capacitance, and cytoplasm conductivity. Correlation analysis revealed that population doubling level (PDL) correlated with membrane capacitance and cytoplasm conductivity, indicating PDL as a more precise marker of in vitro aging than passage number. Additionally, we demonstrate that membrane capacitance correlates with the osteogenic marker COL1A1 and that cytoplasm conductivity correlates with the adipogenic markers ADIPOQ and FABP4, suggesting that DEP-derived electrical properties serve as label-free biomarkers of differentiation potential. While DEP has previously been applied to BM-hMSCs and AT-hMSCs, and more recently to UC-hMSCs, few studies have provided a direct comparison across all three sources or tracked changes across continuous expansion. These findings underscore the utility of DEP as a label-free approach for assessing hMSC aging and function, offering practical applications for optimizing stem cell expansion and stem cell banking in clinical settings.

In vitro and in vivo assessment of a non-animal sourced chitosan scaffold loaded with xeno-free umbilical cord mesenchymal stromal cells cultured under macromolecular crowding conditions

There is an increasing demand to not only accelerate the development of advanced therapy tissue engineered medicines, but to also eliminate xenogeneic materials from their development cycle. With these in mind, herein we first assessed the influence of carrageenan as macromolecular crowding agent to enhance and accelerate extracellular matrix deposition in xeno-free human umbilical cord mesenchymal stromal cell cultures and we developed and characterised a non-animal sourced chitosan scaffold. Following appropriate in vitro experimentation, a splinted nude mouse wound healing model was used to assess wound closure and scar size of non-treated control, non-animal sourced chitosan scaffold, non-animal sourced chitosan scaffold loaded with xeno-free human umbilical cord mesenchymal stromal cells and non-animal sourced chitosan scaffold loaded with xeno-free human umbilical cord mesenchymal stromal cells cultured under macromolecular crowding conditions groups. Across all three donors, carrageenan supplementation significantly increased collagen deposition at day 5, day 8 and day 11 without affecting cell morphology, viability, DNA concentration and metabolic activity. Through freeze drying, a non-animal sourced chitosan sponge was developed with appropriate structural and mechanical properties for wound healing applications. In vitro biological analysis made apparent that neither the scaffold nor macromolecular crowding negatively impacted xeno-free human umbilical cord mesenchymal stromal cell metabolic activity and proliferation. In vivo biological analysis revealed no significant differences between the groups in wound closure and scar size, raising question about the suitability of the model. In any case, this work sets the foundations for the development of completely xeno-free tissue engineered medicines.

Network-based drug repurposing identifies small molecule drugs as immune checkpoint inhibitors for endometrial cancer

Endometrial cancer (EC) is the 6th most common cancer in women around the world. Alone in the United States (US), 66,200 new cases and 13,030 deaths are expected to occur in 2023 which needs the rapid development of potential therapies against EC. Here, a network-based drug-repurposing strategy is developed which led to the identification of 16 FDA-approved drugs potentially repurposable for EC as potential immune checkpoint inhibitors (ICIs). A network of EC-associated immune checkpoint proteins (ICPs)-induced protein interactions (P-ICP) was constructed. As a result of network analysis of P-ICP, top key target genes closely interacting with ICPs were shortlisted followed by network proximity analysis in drug-target interaction (DTI) network and pathway cross-examination which identified 115 distinct pathways of approved drugs as potential immune checkpoint inhibitors. The presented approach predicted 16 drugs to target EC-associated ICPs-induced pathways, three of which have already been used for EC and six of them possess immunomodulatory properties providing evidence of the validity of the strategy. Classification of the predicted pathways indicated that 15 drugs can be divided into two distinct pathway groups, containing 17 immune pathways and 98 metabolic pathways. In addition, drug-drug correlation analysis provided insight into finding useful drug combinations. This fair and verified analysis creates new opportunities for the quick repurposing of FDA-approved medications in clinical trials.

Donor Sex and Passage Conditions Influence MSC Osteogenic Response in Mineralized Collagen Scaffolds

Contemporary tissue engineering efforts often seek to use mesenchymal stem cells (MSCs) due to their multi-potent potential and ability to generate a pro-regenerative secretome. While many have reported the influence of matrix environment on MSC osteogenic response, few have investigated the effects of donor and sex. Here, a well-defined mineralized collagen scaffold is used to study the influence of passage number and donor-reported sex on MSC proliferation and osteogenic potential. A library of bone marrow and adipose tissue-derived stem cells from eight donors to examine donor viability in osteogenic capacity in mineralized collagen scaffolds is obtained. MSCs displayed reduced proliferative capacity as a function of passage duration. Further, MSCs showed significant sex-associated variability in osteogenic capacity. Notably, MSCs from male donors displayed significantly higher cell proliferation while MSCs from female donors displayed significantly higher osteogenic response via increased alkaline phosphate activity, osteoprotegerin release, and mineral formation in vitro. The study highlights the essentiality of including donor-reported sex as an experimental variable and reporting culture expansion in future studies of biomaterial regenerative potential.

Evidence-Based Clinical Practice Guidelines on Regenerative Medicine Treatment for Chronic Pain: A Consensus Report from a Multispecialty Working Group

Purpose

Injectable biologics have not only been described and developed to treat dermal wounds, cardiovascular disease, and cancer, but have also been reported to treat chronic pain conditions. Despite emerging evidence supporting regenerative medicine therapy for pain, many aspects remain controversial.

Methods

The American Society of Pain and Neuroscience (ASPN) identified the educational need for an evidence-based guideline on regenerative medicine therapy for chronic pain. The executive board nominated experts spanning multiple specialties including anesthesiology, physical medicine and rehabilitation, and sports medicine based on expertise, publications, research, and clinical practice. A steering committee selected preliminary questions, which were reviewed and refined. Evidence was appraised using the United States Preventive Services Task Force (USPSTF) criteria for evidence level and degree of recommendation. Using a modified Delphi approach, consensus points were distributed to all collaborators and each collaborator voted on each point. If collaborators provided a decision of "disagree" or "abstain", they were invited to provide a rationale in a non-blinded fashion to the committee chair, who incorporated the respective comments and distributed revised versions to the committee until consensus was achieved.

Results

Sixteen questions were selected for guideline development. Questions that were addressed included type of injectable biologics and mechanism, evidence in treating chronic pain indications (eg, tendinopathy, muscular pathology, osteoarthritis, intervertebral disc disease, neuropathic pain), role in surgical augmentation, dosing, comparative efficacy between injectable biologics, peri-procedural practices to optimize therapeutic response and quality of injectate, federal regulations, and complications with mitigating strategies.

Conclusion

In well-selected individuals with certain chronic pain indications, use of injectable biologics may provide superior analgesia, functionality, and/or quality of life compared to conventional medical management or placebo. Future high-quality randomized clinical trials are warranted with implementation of minimum reporting standards, standardization of preparation protocols, investigation of dose-response associations, and comparative analysis between different injectable biologics.

New insights into dairy management and the prevention and treatment of osteoporosis: The shift from single nutrient to dairy matrix effects-A review

Dairy is recognized as a good source of calcium, which is important for preventing osteoporosis. However, the relationship between milk and bone health is more complex than just calcium supplementation. It is unwise to focus solely on observing the effects of a single nutrient. Lactose, proteins, and vitamins in milk, as well as fatty acids, oligosaccharides, and exosomes, all work together with calcium to enhance its bioavailability and utilization efficiency through various mechanisms. We evaluate the roles of dairy nutrients and active ingredients in maintaining bone homeostasis from the perspective of the dairy matrix effects. Special attention is given to threshold effects, synergistic effects, and associations with the gut-bone axis. We also summarize the associations between probiotic/prebiotic milk, low-fat/high-fat milk, lactose-free milk, and fortified milk with a reduced risk of osteoporosis and discuss the potential benefits and controversies of these dairy products. Moreover, we examine the role of dairy products in increasing peak bone mass during adolescence and reducing bone loss in old age. It provides a theoretical reference for the use of dairy products in the accurate prevention and management of osteoporosis and related chronic diseases and offers personalized dietary recommendations for bone health in different populations.

Adipose Tissue and Umbilical Cord Tissue: Potential Sources of Mesenchymal Stem Cells for Liver Fibrosis Treatment

Background/Aims

Mesenchymal stem cells (MSCs) are potential alternatives for liver fibrosis treatment; however, their optimal sources remain uncertain. This study compares the ex-vivo expansion characteristics of MSCs obtained from adipose tissue (AT) and umbilical cord (UC) and assesses their therapeutic potential for liver fibrosis treatment.

Methods

Since MSCs from early to mid-passage numbers (P2-P6) are preferable for cellular therapy, we investigated the growth kinetics of AT-MSCs and UC-MSCs up to P6 and evaluated their therapeutic effects in a rat model of liver fibrosis induced by diethylnitrosamine.

Results

Results from the expansion studies demonstrated that both cell types exhibited bona fide characteristics of MSCs, including surface antigens, pluripotent gene expression, and differentiation potential. However, AT-MSCs demonstrated a shorter doubling time (58.2 ± 7.3 vs. 82.3 ± 4.3 h; P < 0.01) and a higher population doubling level (10.1 ± 0.7 vs. 8.2 ± 0.3; P < 0.01) compared to UC-MSCs, resulting in more cellular yield (230 ± 9.0 vs. 175 ± 13.2 million) in less time. Animal studies demonstrated that both MSC types significantly reduced liver fibrosis (P < 0.05 vs. the control group) while also improving liver function and downregulating fibrosis-associated gene expression.

Conclusion

AT-MSCs and UC-MSCs effectively reduce liver fibrosis. However, adipose cultures display an advantage by yielding a higher number of MSCs in a shorter duration, rendering them a viable choice for scenarios requiring immediate single-dose administration, often encountered in clinical settings.

Role of secretomes in cell-free therapeutic strategies in regenerative medicine

After an injury, peripheral nervous system neurons have the potential to rebuild their axons by generating a complicated activation response. Signals from the damaged axon are required for this genetic transition to occur. Schwann cells (SCs) near a damaged nerve's distal stump also play a role in the local modulation of axonal programs, not only via cell-to-cell contacts but also through secreted signals (the secretome). The secretome is made up of all the proteins that the cell produces, such as cytokines, growth factors, and extracellular vesicles. The released vesicles may carry signaling proteins as well as coding and regulatory RNAs, allowing for multilayer communication. The secretome of SCs is now well understood as being critical for both orchestrating Wallerian degeneration and maintaining axonal regeneration. As a consequence, secretome has emerged as a feasible tissue regeneration alternative to cell therapy. Separate SC secretome components have been used extensively in the lab to promote peripheral nerve regeneration after injury. However, in neurological therapies, the secretome generated by mesenchymal (MSC) or other derived stem cells has been the most often used. In fact, the advantages of cell treatment have been connected to the release of bioactive chemicals and extracellular vesicles, which make up MSCs' secretome.

Possibilities and efficiency of MSC co-transfection for gene therapy

Mesenchymal stem/stromal cells (MSCs) are not only capable of self-renewal, trans-differentiation, homing to damaged tissue sites and immunomodulation by secretion of trophic factors but are also easy to isolate and expand. Because of these characteristics, they are used in numerous clinical trials for cell therapy including immune and neurological disorders, diabetes, bone and cartilage diseases and myocardial infarction. However, not all trials have successful outcomes, due to unfavourable microenvironmental factors and the heterogenous nature of MSCs. Therefore, genetic manipulation of MSCs can increase their prospect. Currently, most studies focus on single transfection with one gene. Even though the introduction of more than one gene increases the complexity, it also increases the effectivity as different mechanism are triggered, leading to a synergistic effect. In this review we focus on the methodology and efficiency of co-transfection, as well as the opportunities and pitfalls of these genetically engineered cells for therapy.

Extracellular vesicle biogenesis of three-dimensional human pluripotent stem cells in a novel Vertical-Wheel bioreactor

Extracellular vesicles (EVs) secreted by human-induced pluripotent stem cells (hiPSCs) have great potential as cell-free therapies in various diseases, including prevention of blood-brain barrier senescence and stroke. However, there are still challenges in pre-clinical and clinical use of hiPSC-EVs due to the need for large-scale production of a large quantity. Vertical-Wheel bioreactors (VWBRs) have design features that allow the biomanufacturing of hiPSC-EVs using a scalable aggregate or microcarrier-based culture system under low shear stress. EV secretion by undifferentiated hiPSCs expanded as 3-D aggregates and on Synthemax II microcarriers in VWBRs were investigated. Additionally, two types of EV collection media, mTeSR and HBM, were compared. The hiPSCs were characterized by metabolite and transcriptome analysis as well as EV biogenesis markers. Protein and microRNA cargo were analysed by proteomics and microRNA-seq, respectively. The in vitro functional assays of microglia stimulation and proliferation were conducted. HiPSCs expanded as 3-D aggregates and on microcarriers had comparable cell number, while microcarrier culture had higher glucose consumption, higher glycolysis and lower autophagy gene expression based on mRNA-seq. The microcarrier cultures had at least 17-23 fold higher EV secretion, and EV collection in mTeSR had 2.7-3.7 fold higher yield than HBM medium. Microcarrier culture with mTeSR EV collection had a smaller EV size than other groups, and the cargo was enriched with proteins (proteomics) and miRNAs (microRNA-seq) reducing apoptosis and promoting cell proliferation (e.g. Wnt-related pathways). hiPSC-EVs demonstrated the ability of stimulating proliferation and M2 polarization of microglia in vitro. HiPSC expansion on microcarriers produces much higher yields of EVs than hiPSC aggregates in VWBRs. EV collection in mTeSR increases yield compared to HBM. The biomanufactured EVs from microcarrier culture in mTeSR have exosomal characteristics and are functional in microglia stimulation, which paves the ways for future in vivo anti-aging study.

Spheroid size influences cellular senescence and angiogenic potential of mesenchymal stromal cell-derived soluble factors and extracellular vesicles

Introduction: The secretome of mesenchymal stromal cells (MSCs) serves as an innovative tool employed in the regenerative medicine approach. In this particular context, three-dimensional (3D) culture systems are widely utilized to better replicate in vivo conditions and facilitate prolonged cell maintenance during culture. The use of spheroids enables the preservation of the classical phenotypical characteristics of MSCs. However, the distinct microenvironment within the spheroid may impact the secretome, thereby enhancing the angiogenic properties of adult MSCs that typically possess a reduced angiogenic potential compared to MSCs derived from perinatal tissues due to the hypoxia created in the internal region of the spheroid. Methods: In this study, large spheroids (2,600 cells, ∼300 μm diameter) and small spheroids (1,000 cells, ∼200 μm diameter) were used to examine the role of spheroid diameter in the generation of nutrients and oxygen gradients, cellular senescence, and the angiogenic potential of secreted factors and extracellular vesicles (EVs). Results: In this study, we demonstrate that large spheroids showed increased senescence and a secretome enriched in pro-angiogenic factors, as well as pro-inflammatory and anti-angiogenic cytokines, while small spheroids exhibited decreased senescence and a secretome enriched in pro-angiogenic molecules. We also demonstrated that 3D culture led to a higher secretion of EVs with classical phenotypic characteristics. Soluble factors and EVs from small spheroids exhibited higher angiogenic potential in a human umbilical vein endothelial cell (HUVEC) angiogenic assay. Discussion: These findings highlighted the necessity of choosing the appropriate culture system for obtaining soluble factors and EVs for specific therapeutic applications.

DONOR VARIABILITY IN HUMAN MESENCHYMAL STEM CELL OSTEOGENIC RESPONSE AS A FUNCTION OF PASSAGE CONDITIONS AND DONOR SEX

Contemporary tissue engineering efforts often seek to use mesenchymal stem cells (MSCs) due to their potential to differentiate to various tissue-specific cells and generate a pro-regenerative secretome. While MSC differentiation and therapeutic potential can differ as a function of matrix environment, it may also be widely influenced as a function of donor-to-donor variability. Further, effects of passage number and donor sex may further convolute the identification of clinically effective MSC-mediated regeneration technologies. We report efforts to adapt a well-defined mineralized collagen scaffold platform to study the influence of MSC proliferation and osteogenic potential as a function of passage number and donor sex. Mineralized collagen scaffolds broadly support MSC osteogenic differentiation and regenerative potency in the absence of traditional osteogenic supplements for a wide range of MSCs (rabbit, rat, porcine, human). We obtained a library of bone marrow and adipose tissue derived stem cells to examine donor-variability of regenerative potency in mineralized collagen scaffolds. MSCs displayed reduced proliferative capacity as a function of passage duration. Further, MSCs showed significant sex-based differences. Notably, MSCs from male donors displayed significantly higher metabolic activity and proliferation while MSCs from female donor displayed significantly higher osteogenic response via increased alkaline phosphate activity, osteoprotegerin release, and mineral formation in vitro. Our study highlights the essentiality of considering MSC donor sex and culture expansion in future studies of biomaterial regenerative potential.

Management of Rheumatoid Arthritis: Possibilities and Challenges of Mesenchymal Stromal/Stem Cell-Based Therapies

Rheumatoid arthritis (RA) is a highly prevalent, chronic, and progressive autoimmune disorder primarily affecting joints and muscles. The associated inflammation, pain, and motor restriction negatively impact patient quality of life (QOL) and can even contribute to premature mortality. Further, conventional treatments such as antiinflammatory drugs are only symptomatic. Substantial progress has been made on elucidating the etiopathology of overt RA, in particular the contributions of innate and adaptive immune system dysfunction to chronic inflammation. Although the precise mechanisms underlying onset and progression remain elusive, the discovery of new drug targets, early diagnosis, and new targeted treatments have greatly improved the prognosis and QOL of patients with RA. However, a sizable proportion of patients develop severe adverse effects, exhibit poor responses, or cannot tolerate long-term use of these drugs, necessitating more effective and safer therapeutic alternatives. Mounting preclinical and clinical evidence suggests that the transplantation of multipotent adult stem cells such as mesenchymal stromal/stem cells is a safe and effective treatment strategy for controlling chronic inflammation and promoting tissue regeneration in patients with intractable diseases, including RA. This review describes the current status of MSC-based therapies for RA as well as the opportunities and challenges to broader clinical application.

Aged mesenchymal stem cells and inflammation: from pathology to potential therapeutic strategies

Natural ageing of organisms and corresponding age-related diseases result mainly from stem cell ageing and "inflammaging". Mesenchymal stem cells (MSCs) exhibit very high immune-regulating capacity and are promising candidates for immune-related disease treatment. However, the effect of MSC application is not satisfactory for some patients, especially in elderly individuals. With ageing, MSCs undergo many changes, including altered cell population reduction and differentiation ability, reduced migratory and homing capacity and, most important, defective immunosuppression. It is necessary to explore the relationship between the "inflammaging" and aged MSCs to prevent age-related diseases and increase the therapeutic effects of MSCs. In this review, we discuss changes in naturally ageing MSCs mainly from an inflammation perspective and propose some ideas for rejuvenating aged MSCs in future treatments.

Bovine Fibroblast-Derived Extracellular Matrix Promotes the Growth and Preserves the Stemness of Bovine Stromal Cells during In Vitro Expansion

Cultivated meat is a fast-growing research field and an industry with great potential to overcome the limitations of traditional meat production. Cultivated meat utilizes cell culture and tissue engineering technologies to culture a vast number of cells in vitro and grow/assemble them into structures mimicking the muscle tissues of livestock animals. Stem cells with self-renewal and lineage-specific differentiation abilities have been considered one of the key cell sources for cultivated meats. However, the extensive in vitro culturing/expansion of stem cells results in a reduction in their abilities to proliferate and differentiate. Extracellular matrix (ECM) has been used as a culturing substrate to support cell expansion for cell-based therapies in regenerative medicine due to its resemblance to the native microenvironment of cells. In this study, the effect of the ECM on the expansion of bovine umbilical cord stromal cells (BUSC) in vitro was evaluated and characterized. BUSCs with multi-lineage differentiation potentials were isolated from bovine placental tissue. Decellularized ECM prepared from a confluent monolayer of bovine fibroblasts (BF) is free of cellular components but contains major ECM proteins such as fibronectin and type I collagen and ECM-associated growth factors. Expansion of BUSC on ECM for three passages (around three weeks) resulted in about 500-fold amplification, while cells were amplified less than 10-fold when cultured on standard tissue culture plates (TCP). Moreover, the presence of ECM reduced the requirement for serum in the culture medium. Importantly, the cells amplified on ECM retained their differentiation abilities better than cells cultured on TCP. The results of our study support the notion that monolayer cell-derived ECM may be a strategy to expand bovine cells in vitro effectively and efficiently.

Managing the Heterogeneity of Mesenchymal Stem Cells for Cartilage Regenerative Therapy: A Review

Articular cartilage defects commonly result from trauma and are associated with significant morbidity. Since cartilage is an avascular, aneural, and alymphatic tissue with a poor intrinsic healing ability, the regeneration of functional hyaline cartilage remains a difficult clinical problem. Mesenchymal stem cells (MSCs) are multipotent cells with multilineage differentiation potential, including the ability to differentiate into chondrocytes. Due to their availability and ease of ex vivo expansion, clinicians are increasingly applying MSCs in the treatment of cartilage lesions. However, despite encouraging pre-clinical and clinical data, inconsistencies in MSC proliferative and chondrogenic potential depending on donor, tissue source, cell subset, culture conditions, and handling techniques remain a key barrier to widespread clinical application of MSC therapy in cartilage regeneration. In this review, we highlight the strategies to manage the heterogeneity of MSCs ex vivo for more effective cartilage repair, including reducing the MSC culture expansion period, and selecting MSCs with higher chondrogenic potential through specific genetic markers, surface markers, and biophysical attributes. The accomplishment of a less heterogeneous population of culture-expanded MSCs may improve the scalability, reproducibility, and standardisation of MSC therapy for clinical application in cartilage regeneration.

Toward transplantation tolerance with adipose tissue-derived therapeutics

Solid organ and composite tissue allotransplanation have been widely applied to treat end-stage organ failure and massive tissue defects, respectively. Currently there are a lot of research endeavors focusing on induction of transplantation tolerance, to relieve the burden derived from long-term immunosuppressant uptake. The mesenchymal stromal cells (MSCs) have been demonstrated with potent immunomodulatory capacities and applied as promising cellular therapeutics to promote allograft survival and induce tolerance. As a rich source of adult MSCs, adipose tissue provides additional advantages of easy accessibility and good safety profile. In recent years, the stromal vascular fraction (SVF) isolated from adipose tissues following enzymatic or mechanical processing without in vitro culture and expansion has demonstrated immunomodulatory and proangiogenic properties. Furthermore, the secretome of AD-MSCs has been utilized in transplantation field as a potential "cell-free" therapeutics. This article reviews recent studies that employ these adipose-derived therapeutics, including AD-MSCs, SVF, and secretome, in various aspects of organ and tissue allotransplantation. Most reports validate their efficacies in prolonging allograft survival. Specifically, the SVF and secretome have performed well for graft preservation and pretreatment, potentially through their proangiogenic and antioxidative capacities. In contrast, AD-MSCs were suitable for peri-transplantation immunosuppression. The proper combination of AD-MSCs, lymphodepletion and conventional immunosuppressants could consistently induce donor-specific tolerance to vascularized composite allotransplants (VCA). For each type of transplantation, optimizing the choice of therapeutics, timing, dose, and frequency of administration may be required. Future progress in the application of adipose-derived therapeutics to induce transplantation tolerance will be further benefited by continued research into their mechanisms of action and the development of standardized protocols for isolation methodologies, cell culture, and efficacy evaluation.

Bioreactor Expansion Reconfigures Metabolism and Extracellular Vesicle Biogenesis of Human Adipose-derived Stem Cells In Vitro

Human mesenchymal stem cells (hMSCs), including human adipose tissue-derived stem cells (hASCs), as well as the secreted extracellular vesicles (EVs), are promising therapeutics in treating inflammatory and neural degenerative diseases. However, prolonged expansion can lead to cellular senescence characterized by a gradual loss of self-renewal ability while altering secretome composition and EV generation. Additionally, hMSCs are highly sensitive to biophysical microenvironment in bioreactor systems utilized in scaling production. In this study, hASCs grown on Plastic Plus or Synthemax II microcarriers in a spinner flask bioreactor (SFB) system were compared to traditional 2D culture. The SFB microenvironment was found to increase the expression of genes associated with hASC stemness, nicotinamide adenine dinucleotide (NAD+) metabolism, glycolysis, and the pentose phosphate pathway as well as alter cytokine secretion (e.g., PGE2 and CXCL10). Elevated reactive oxidative species levels in hASCs of SFB culture were observed without increasing rates of cellular senescence. Expression levels of Sirtuins responsible for preventing cellular senescence through anti-oxidant and DNA repair mechanisms were also elevated in SFB cultures. In particular, the EV biogenesis genes were significantly upregulated (3-10 fold) and the EV production increased 40% per cell in SFB cultures of hASCs. This study provides advanced understanding of hASC sensitivity to the bioreactor microenvironment for EV production and bio-manufacturing towards the applications in treating inflammatory and neural degenerative diseases.

Engineering Human Mesenchymal Bodies in a Novel 3D-Printed Microchannel Bioreactor for Extracellular Vesicle Biogenesis

Human Mesenchymal Stem Cells (hMSCs) and their derived products hold potential in tissue engineering and as therapeutics in a wide range of diseases. hMSCs possess the ability to aggregate into "spheroids", which has been used as a preconditioning technique to enhance their therapeutic potential by upregulating stemness, immunomodulatory capacity, and anti-inflammatory and pro-angiogenic secretome. Few studies have investigated the impact on hMSC aggregate properties stemming from dynamic and static aggregation techniques. hMSCs' main mechanistic mode of action occur through their secretome, including extracellular vesicles (EVs)/exosomes, which contain therapeutically relevant proteins and nucleic acids. In this study, a 3D printed microchannel bioreactor was developed to dynamically form hMSC spheroids and promote hMSC condensation. In particular, the manner in which dynamic microenvironment conditions alter hMSC properties and EV biogenesis in relation to static cultures was assessed. Dynamic aggregation was found to promote autophagy activity, alter metabolism toward glycolysis, and promote exosome/EV production. This study advances our knowledge on a commonly used preconditioning technique that could be beneficial in wound healing, tissue regeneration, and autoimmune disorders.

Phenotypic, metabolic, and biogenesis properties of human stem cell-derived cerebellar spheroids

Human cerebellum consists of high density and complexity of neurons. Thus, it is challenging to differentiate cerebellar-like organoids with similar cellular markers and function to the human brain. Our previous study showed that the combination of retinoic acid (RA), Wingless/integrated (Wnt) activator, and Sonic Hedgehog (SHH) activator promotes cerebellar differentiation from human induced pluripotent stem cells (hiPSCs). This study examined phenotypic, metabolic, and biogenesis in early cerebellar development. Cerebellum spheroids were differentiated from human iPSK3 cells. During day 7–14, RA and Wnt activator CHIR99021 were used and SHH activator purmorphamine (PMR) was added later to promote ventralization. Gene expression for early cerebellar layer markers, metabolism, and extracellular vesicle (EV) biogenesis were characterized. Zinc-induced neurotoxicity was investigated as a proof-of-concept of neurotoxicity study. Flow cytometry results showed that there was no significant difference in NEPH3, PTF1A, OLIG2, and MATH1 protein expression between RCP (RA-CHIR-PMR) versus the control condition. However, the expression of cerebellar genes for the molecular layer (BHLE22), the granule cell layer (GABRB2, PAX6, TMEM266, KCNIP4), the Bergmann glial cells (QK1, DAO), and the Purkinje cell layer (ARHGEF33, KIT, MX1, MYH10, PPP1R17, SCGN) was significantly higher in the RCP condition than the control. The shift in metabolic pathways toward glycolysis was observed for RCP condition. The EV biogenesis marker expression was retained. Mild zinc-induced neurotoxicity may exist when zinc exposure exceeds 1.0 µM. RCP treatment can promote specific cerebellar-like differentiation from hiPSCs indicated by gene expression of early cerebellar markers and regionally enriched genes. The higher cerebellar marker expression is accompanied by the elevated glycolysis with the retained EV biogenesis. This study should advance the understanding of biomarkers during early cerebellar development for cerebellum organoid engineering and neurotoxicity study.

Engineering extracellular vesicles by three-dimensional dynamic culture of human mesenchymal stem cells

Human mesenchymal stem cell (hMSC) derived extracellular vesicles (EVs) have shown therapeutic potential in recent studies. However, the corresponding therapeutic components are largely unknown, and scale-up production of hMSC EVs is a major challenge for translational applications. In the current study, hMSCs were grown as 3D aggregates under wave motion to promote EV secretion. Results demonstrate that 3D hMSC aggregates promote activation of the endosomal sorting complexes required for transport (ESCRT)-dependent and -independent pathways. mRNA sequencing revealed global transcriptome alterations for 3D hMSC aggregates. Compared to 2D-hMSC-EVs, the quantity of 3D-hMSC-EVs was enhanced significantly (by 2-fold), with smaller sizes, higher miR-21 and miR-22 expression, and an altered protein cargo (e.g., upregulation of cytokines and anti-inflammatory factors) uncovered by proteomics analysis, possibly due to altered EV biogenesis. Functionally, 3D-hMSC-EVs rejuvenated senescent stem cells and exhibited enhanced immunomodulatory potentials. In summary, this study provides a promising strategy for scalable production of high-quality EVs from hMSCs with enhanced therapeutic potential.

Heterogeneity of In Vitro Expanded Mesenchymal Stromal Cells and Strategies to Improve Their Therapeutic Actions

Beneficial properties of mesenchymal stromal cells (MSCs) have prompted their use in preclinical and clinical research. Accumulating evidence has been provided for the therapeutic effects of MSCs in several pathologies, including neurodegenerative diseases, myocardial infarction, skin problems, liver disorders and cancer, among others. Although MSCs are found in multiple tissues, the number of MSCs is low, making in vitro expansion a required step before MSC application. However, culture-expanded MSCs exhibit notable differences in terms of cell morphology, physiology and function, which decisively contribute to MSC heterogeneity. The changes induced in MSCs during in vitro expansion may account for the variability in the results obtained in different MSC-based therapy studies, including those using MSCs as living drug delivery systems. This review dissects the different changes that occur in culture-expanded MSCs and how these modifications alter their therapeutic properties after transplantation. Furthermore, we discuss the current strategies developed to improve the beneficial effects of MSCs for successful clinical implementation, as well as potential therapeutic alternatives.

3D Tissue-Engineered Vascular Drug Screening Platforms: Promise and Considerations

Despite the efforts devoted to drug discovery and development, the number of new drug approvals have been decreasing. Specifically, cardiovascular developments have been showing amongst the lowest levels of approvals. In addition, concerns over the adverse effects of drugs to the cardiovascular system have been increasing and resulting in failure at the preclinical level as well as withdrawal of drugs post-marketing. Besides factors such as the increased cost of clinical trials and increases in the requirements and the complexity of the regulatory processes, there is also a gap between the currently existing pre-clinical screening methods and the clinical studies in humans. This gap is mainly caused by the lack of complexity in the currently used 2D cell culture-based screening systems, which do not accurately reflect human physiological conditions. Cell-based drug screening is widely accepted and extensively used and can provide an initial indication of the drugs' therapeutic efficacy and potential cytotoxicity. However, in vitro cell-based evaluation could in many instances provide contradictory findings to the in vivo testing in animal models and clinical trials. This drawback is related to the failure of these 2D cell culture systems to recapitulate the human physiological microenvironment in which the cells reside. In the body, cells reside within a complex physiological setting, where they interact with and respond to neighboring cells, extracellular matrix, mechanical stress, blood shear stress, and many other factors. These factors in sum affect the cellular response and the specific pathways that regulate variable vital functions such as proliferation, apoptosis, and differentiation. Although pre-clinical in vivo animal models provide this level of complexity, cross species differences can also cause contradictory results from that seen when the drug enters clinical trials. Thus, there is a need to better mimic human physiological conditions in pre-clinical studies to improve the efficiency of drug screening. A novel approach is to develop 3D tissue engineered miniaturized constructs in vitro that are based on human cells. In this review, we discuss the factors that should be considered to produce a successful vascular construct that is derived from human cells and is both reliable and reproducible.

Gene Ontology Groups and Signaling Pathways Regulating the Process of Avian Satellite Cell Differentiation

Modern science is becoming increasingly committed to environmentally friendly solutions, mitigating the impact of the developing human civilisation on the environment. One of the leading fields aimed at sustainable agriculture is in vitro meat production. Cellular agriculture aims to provide a source of animal-free meat products, which would decrease worldwide nutritional dependency on animal husbandry, thereby reducing the significant impact of this industry on Earth’s climate. However, while some studies successfully produced lab-based meat on a small scale, scalability of this approach requires significant optimisation of the methodology in order to ensure its viability on an industrial scale. One of the methodological promises of in vitro meat production is the application of cell suspension-based bioreactors. Hence, this study focused on a complex transcriptomic comparison of adherent undifferentiated, differentiated and suspension-cultured myosatellite cells, aiming to determine the effects of different culture methods on their transcriptome. Modern next-generation sequencing (RNAseq) was used to determine the levels of transcripts in the cultures’ cell samples. Then, differential expression and pathway analyses were performed using bionformatical methods. The significantly regulated pathways included: EIF2, mTOR, GP6, integrin and HIFα signalling. Differential regulation of gene expression, as well as significant enrichment and modulation of pathway activity, suggest that suspension culture potentially promotes the ex vivo-associated loss of physiological characteristics and gain of plasticity. Therefore, it seems that suspension cultures, often considered the desired method for in vitro meat production, require further investigation to fully elucidate their effect on myosatellite cells and, therefore, possibly enable their easier scalability to ensure suitability for industrial application.

Studying the Inflammatory Responses to Amyloid Beta Oligomers in Brain-Specific Pericyte and Endothelial Co-culture from Human Stem Cells

Background

Recently, the in vitro blood brain barrier (BBB) models derived from human pluripotent stem cells have been given extensive attention in therapeutics due to the implications it has with the health of the central nervous system. It is essential to create an accurate BBB model in vitro in order to better understand the properties of the BBB and how it can respond to inflammatory stimulation and be passed by targeted or non-targeted cell therapeutics, more specifically extracellular vesicles.

Methods

Brain-specific pericytes (iPCs) were differentiated from iPSK3 cells using dual SMAD signaling inhibitors and Wnt activation plus fibroblast growth factor 2 (FGF-2). The derived cells were characterized by immunostaining, flow cytometry and RT-PCR. In parallel, blood vessels organoids were derived using Wnt activation, BMP4, FGF2, VEGF and SB431542. The organoids were replated and treated with retinoic acid to enhance the blood brain barrier (BBB) features in the differentiated brain endothelial cells (iECs). Co-culture was performed for the iPCs and iECs in transwell system and 3-D microfluidics channels.

Results

The derived iPCs expressed common markers PDGFRb and NG2, as well as brain-specific genes FOXF2, ABCC9, KCNJ8, and ZIC1. The derived iECs expressed common endothelial cell markers CD31, VE-cadherin, as well as BBB-associated genes BRCP, GLUT-1, PGP, ABCC1, OCLN, SLC2A1. The co-culture of the two cell types responded to the stimulation of amyloid β42 oligomers by the upregulation of expression of TNFa, IL6, NFKB, Casp3, SOD2 and TP53. The co-culture also showed the property of trans-endothelial electrical resistance. The proof-of-concept vascularization strategy was demonstrated in a 3-D microfluidics-based device.

Conclusion

The derived iPCs and iECs have brain-specific properties and the co-culture of iPCs and iECs provides an in vitro BBB model that show inflammatory response. This study has significance in establishing micro-physiological systems for neurological disease modeling and drug screening.

Polychromatic Flow Cytometric Analysis of Stromal Vascular Fraction from Lipoaspirate and Microfragmented Counterparts Reveals Sex-Related Immunophenotype Differences

Mesenchymal stem/stromal cells or medicinal signaling cells (MSC)-based therapy holds promise as a beneficial strategy for treating knee OA (osteoarthritis), but there is no standardized protocols nor mechanistic understanding. In order to gain a better insight into the human MSC from adipose tissue applied for autologous OA treatment, we performed extensive comparative immunophenotyping of the stromal vascular fraction from lipoaspirate or microfragmented lipoaspirates by polychromatic flow cytometry and investigated the cellular components considered responsible for cartilage regeneration. We found an enrichment of the regenerative cellular niche of the clinically applied microfragmented stromal vascular fraction. Sex-related differences were observed in the MSC marker expression and the ratio of the progenitor cells from fresh lipoaspirate, which, in female patients, contained a higher expression of CD90 on the three progenitor cell types including pericytes, a higher expression of CD105 and CD146 on CD31^highCD34^high endothelial progenitors as well as of CD73 on supra-adventitialadipose stromal cells. Some of these MSC-expression differences were present after microfragmentation and indicated a differential phenotype pattern of the applied MSC mixture in female and male patients. Our results provide a better insight into the heterogeneity of the adipose MSC subpopulations serving as OA therapeutics, with an emphasis on interesting differences between women and men.

A Novel 3D Culture Model of Human ASCs Reduces Cell Death in Spheroid Cores and Maintains Inner Cell Proliferation Compared With a Nonadherent 3D Culture

3D cell culture technologies have recently shown very valuable promise for applications in regenerative medicine, but the most common 3D culture methods for mesenchymal stem cells still have limitations for clinical application, mainly due to the slowdown of inner cell proliferation and increase in cell death rate. We previously developed a new 3D culture of adipose-derived mesenchymal stem cells (ASCs) based on its self-feeder layer, which solves the two issues of ASC 3D cell culture on ultra-low attachment (ULA) surface. In this study, we compared the 3D spheroids formed on the self-feeder layer (SLF-3D ASCs) with the spheroids formed by using ULA plates (ULA-3D ASCs). We discovered that the cells of SLF-3D spheroids still have a greater proliferation ability than ULA-3D ASCs, and the volume of these spheroids increases rather than shrinks, with more viable cells in 3D spheroids compared with the ULA-3D ASCs. Furthermore, it was discovered that the SLF-3D ASCs are likely to exhibit the abovementioned unique properties due to change in the expression level of ECM-related genes, like COL3A1, MMP3, HAS1, and FN1. These results indicate that the SLF-3D spheroid is a promising way forward for clinical application.

The effect of mesenchymal stem cells lyophilisate femoral artery of rat anastomosis: A histopathological and histomorphometric study

BACKGROUND AND OBJECTIVE

Mesenchymal Stem Cells (MSCs) are well known for their tissue regeneration enhancing effect and their contribution to immune regulation. However, their contribution to the healing process of femoral artery anastomosis, especially to endothelialization, has not been studied sufficiently in the clinic. This study was carried out to evaluate the effects of MSC-lyophilisate from the human umbilical cord on anastomosis experimental study in rats histopathologically.

METHOD

After intraperitoneal anesthesia was applied to the rats, the femoral artery was exposed with a 2 cm incision in the right femoral region. After the artery was cut in the experiment and sham groups, femoral artery end-to-end anastomosis was performed using the primary suture technique. MSC-lyophilisate was poured in powder form onto the anastomosed outer surface of the vessel in the treatment group and saline solution was poured to the sham group. No intervention was made to the control group. The data analysis was performed with IBM SPSS Statistics 25.

RESULTS

In the experiment group, flattening of the inner elastic lamina, morphological changes and vacuolization in the muscle fibers, inflammation in the adventitia and significant vascular wall thickening were observed in the femoral arteries of the rats after the intervention. According to the histopathological scoring results, tissue samples belonging to sham and experimental groups showed marked pathological findings such as endothelial damage, flattened areas where the folded structure in the inner elastic lamina disappeared, muscle fiber degeneration and inflammation in the adventitia.

CONCLUSION

Human umbilical cord-origin MSC-lyophilisate application holds an important place in femoral artery surgery. We evaluate that it will be meaningful to determine the MSC-lyophilisate dose for hemostasis without creating thrombus after anastomosis. MSC-lyophilisate will be used to provide hemostasis in areas with local bleeding in the future. In addition, it is recommended to make plans for an in-depth examination of possible problems and cases in future studies.

Adipose Tissue: Understanding the Heterogeneity of Stem Cells for Regenerative Medicine

Adipose-derived stem cells (ASCs) have been increasingly used as a versatile source of mesenchymal stem cells (MSCs) for diverse clinical investigations. However, their applications often become complicated due to heterogeneity arising from various factors. Cellular heterogeneity can occur due to: (i) nomenclature and criteria for definition; (ii) adipose tissue depots (e.g., subcutaneous fat, visceral fat) from which ASCs are isolated; (iii) donor and inter-subject variation (age, body mass index, gender, and disease state); (iv) species difference; and (v) study design (in vivo versus in vitro) and tools used (e.g., antibody isolation and culture conditions). There are also actual differences in resident cell types that exhibit ASC/MSC characteristics. Multilineage-differentiating stress-enduring (Muse) cells and dedifferentiated fat (DFAT) cells have been reported as an alternative or derivative source of ASCs for application in regenerative medicine. In this review, we discuss these factors that contribute to the heterogeneity of human ASCs in detail, and what should be taken into consideration for overcoming challenges associated with such heterogeneity in the clinical use of ASCs. Attempts to understand, define, and standardize cellular heterogeneity are important in supporting therapeutic strategies and regulatory considerations for the use of ASCs.

Agitation in a Microcarrier-based Spinner Flask Bioreactor Modulates Homeostasis of Human Mesenchymal Stem Cells

Human mesenchymal stem cells (hMSCs) are well known in cell therapy due to their secretion of trophic factors, multipotent differentiation potential, and ability for self-renewal. As a result, the number of clinical trials has been steadily increasing over the last decade highlighting the need for in vitro systems capable of producing large quantities of cells to meet growing demands. However, hMSCs are highly sensitive to microenvironment conditions, including shear stress caused by dynamic bioreactor systems, and can lead to alteration of cellular homeostasis. In this study, hMSCs were expanded on microcarriers within a 125 mL spinner flask bioreactor system. Our results demonstrate a three-fold expansion over seven days. Furthermore, our results show that culturing hMSCs in the microcarrier-based suspension bioreactor (compared to static planar culture) results in smaller cell size and higher levels of reactive oxidative species (ROS) and ROS regulator Sirtuin-3, which have implications on the nicotinamide adenine dinucleotide metabolic pathway and metabolic homeostasis. In addition, hMSCs in the bioreactor showed the increased Prostaglandin E₂ secretion as well as reduced the Indoleamine-pyrrole 2,3-dioxygenase secretion upon stimulus with interferon gamma. The results of this study provide understanding of potential hMSC physiology alterations impacted by bioreactor microenvironment during scalable production of hMSCs for biomanufacturing and clinical trials.