Cardiomyocyte grafting for cardiac repair: graft cell death and anti-death strategies

Mesenchymal stem cells enchanced by salidroside to inhibit ferroptosis and improve premature ovarian insufficiency via Keap1/Nrf2/GPX4 signaling

BACKGROUND

Regenerative medicine researches have shown that mesenchymal stem cells (MSCs) may be an effective treatment method for premature ovarian insufficiency (POI). However, the efficacy of MSCs is still limited.

PURPOSE

This study aims to explain whether salidroside and MSCs combination is a therapeutic strategy to POI and to explore salidroside-enhanced MSCs inhibiting ferroptosis via Keap1/Nrf2/GPX4 signaling.

METHODS

The effect of salidroside and MSCs on ovarian granular cells (GCs) was analyzed. After treatment, hormone levels and -fertility of rats were measured. Lipid peroxidation levels, iron deposition and mitochondrial morphology were detected. The genes and proteins of Keap1/Nrf2/GPX4 signaling were examined.

RESULTS

Salidroside and MSCs were found to inhibit cell death of GCs by reducing peroxidation and intracellular ferrous. Salidroside promotes the proliferation of MSCs and supports cell survival in ovary. Salidroside combined with MSCs therapy restored ovarian function, which was better than MSCs monotherapy. Salidroside-enhanced MSCs to inhibit ferroptosis. The results showed activation of the Keap1/Nrf2/GPX4 signaling and an increase in anti-ferroptosis molecule.

CONCLUSIONS

Salidroside-enhanced MSCs as a ferroptosis inhibitor and provide new therapeutic strategies for POI. The possible mechanisms of MSCs were related to maintaining redox homeostasis via a Keap1/Nrf2/GPX4 signaling.

Autoimmunity and clinical pathology amelioration in SLE by dexamethasone primed mesenchymal stem cell derived conditioned media

BACKGROUND

This study aimed to investigate the therapeutic potential of cell-free Dexamethasone (Dex) primed Wharton's jelly Mesenchymal stem cells derived conditioned media (DW) in addressing complications associated with systemic lupus erythematosus (SLE), focusing on its immunomodulatory effects.

METHODS

Peripheral blood mononuclear cells from 74 SLE patients were stimulated and treated with Dex, DW and W. Culture supernatant were evaluated for autoantibody levels, IL-10 and TGF-β by ELISA, Treg subtypes, Breg subtypes, TH17 cells Double negative T cells and inflammatory neutrophils by flow cytometry, IL-10 and IL-17A by qPCR. In vivo studies were performed on 60 pristane induced female BALB/c mice. Dex and DW treatments were evaluated for autoantibody production, proteinuria, immunomodulation of immune cells, organ function, and histopathology. In vivo imaging of internal organs was done using VevoLAZR-X photoacoustic imaging system.

RESULTS

DW treatment significantly expanded different Treg and Bregs subtypes. DW suppressed pathogenic TH17, Double negative T cells and inflammatory neutrophils. Comparative analyses with hydroxychloroquine showed similar effects, with combined treatment enhancing efficacy. Inhibition studies implicated the TGF-β pathway in DW's mechanism. In vivo studies using the PIL mouse model showed that DW treatment reduced mortality, prevented proteinuria, and ameliorated symptoms such as limb inflammation, seizures, and alopecia. Detailed organ-specific evaluations through live imaging and histopathological analyses revealed DW's protective effects on kidneys, liver, lungs, heart, and spleen.

CONCLUSION

DW shows promise as a cell-free biological therapy for SLE and related autoimmune disorders, capable of modulating immune responses effectively without the adverse effects of glucocorticoids.

Cardiomyocytes in Hypoxia: Cellular Responses and Implications for Cell-Based Cardiac Regenerative Therapies

Myocardial infarction (MI) is a severe hypoxic event, resulting in the loss of up to one billion cardiomyocytes (CMs). Due to the limited intrinsic regenerative capacity of the heart, cell-based regenerative therapies, which feature the implantation of stem cell-derived cardiomyocytes (SC-CMs) into the infarcted myocardium, are being developed with the goal of restoring lost muscle mass, re-engineering cardiac contractility, and preventing the progression of MI into heart failure (HF). However, such cell-based therapies are challenged by their susceptibility to oxidative stress in the ischemic environment of the infarcted heart. To maximize the therapeutic benefits of cell-based approaches, a better understanding of the heart environment at the cellular, tissue, and organ level throughout MI is imperative. This review provides a comprehensive summary of the cardiac pathophysiology occurring during and after MI, as well as how these changes define the cardiac environment to which cell-based cardiac regenerative therapies are delivered. This understanding is then leveraged to frame how cell culture treatments may be employed to enhance SC-CMs' hypoxia resistance. In this way, we synthesize both the complex experience of SC-CMs upon implantation and the engineering techniques that can be utilized to develop robust SC-CMs for the clinical translation of cell-based cardiac therapies.

Quantification of the Engraftment Status of Mesenchymal Stem Cells in Glioma Using Dual-Modality Magnetic Resonance Imaging and Bioluminescence Imaging

RATIONALE AND OBJECTIVES

The tumor-tropic properties of mesenchymal stem cells (MSCs) enable them to serve as appealing cellular vehicles for delivering therapeutic agents to treat malignant glioma. However, the exact engraftment status of MSCs in glioma via different administration routes remains unclear due to the lack of quantitative analysis. This study aimed to quantify the engraftment of MSCs in glioma after administration via different routes using non-invasive dual-modality magnetic resonance imaging (MRI) and bioluminescence imaging (BLI).

MATERIALS AND METHODS

MSCs were transduced with a lentivirus overexpressing ferritin heavy chain (FTH) and firefly luciferase (FLUC) reporter genes to yield FTH- and FLUC-overexpressed MSCs (FTH-FLUC-MSCs). Wistar rats bearing intracranial C6 glioma received peritumoral, intratumoral, intra-arterial, and intravenous injection of FTH-FLUC-MSCs, respectively. MRI and BLI were performed to monitor FTH-FLUC-MSCs in vivo.

RESULTS

FTH-FLUC-MSCs administered via peritumoral, intratumoral and intra-arterial routes migrated specially toward the intracranial glioma in vivo, as detected by MRI and BLI. As quantified by the BLI signal intensity, the percentages of FTH-FLUC-MSCs in the glioma were significantly higher with peritumoral injection (61%) and intratumoral injection (71%) compared to intra-arterial injection (30%) and intravenous injection (0%). Peritumorally injected FTH-FLUC-MSCs showed a gradual decline, with approximately 6% of FTH-FLUC-MSCs still retained within the tumor up to 11 days after injection. Meanwhile, the number of FTH-FLUC-MSCs injected via other routes dropped quickly, and none were detectable by day 11 post-injection.

CONCLUSION

Peritumoral delivery of FTH-FLUC-MSCs offers robust engraftment and could be used as the optimal delivery route for treating malignant glioma.

Injectable biodegradable microcarriers for iPSC expansion and cardiomyocyte differentiation

Cell therapy is a potential novel treatment for cardiac regeneration and numerous studies have attempted to transplant cells to regenerate the myocardium lost during myocardial infarction. To date, only minimal improvements to cardiac function have been reported. This is likely to be the result of low cell retention and survival following transplantation. This study aimed to improve the delivery and engraftment of viable cells by using an injectable microcarrier that provides an implantable, biodegradable substrate for attachment and growth of cardiomyocytes derived from induced pluripotent stem cells (iPSC). We describe the fabrication and characterisation of Thermally Induced Phase Separation (TIPS) microcarriers and their surface modification to enable iPSC-derived cardiomyocyte attachment in xeno-free conditions is described. The selected formulation resulted in iPSC attachment, expansion, and retention of pluripotent phenotype. Differentiation of iPSC into cardiomyocytes on the microcarriers is investigated in comparison with culture on 2D tissue culture plastic surfaces. Microcarrier culture is shown to support culture of a mature cardiomyocyte phenotype, be compatible with injectable delivery, and reduce anoikis. The findings from this study demonstrate that TIPS microcarriers provide a supporting matrix for culturing iPSC and iPSC-derived cardiomyocytes in vitro and are suitable as an injectable cell-substrate for cardiac regeneration.

Injectable shear-thinning hydrogels promote oligodendrocyte progenitor cell survival and remyelination in the central nervous system

Cell therapy for the treatment of demyelinating diseases such as multiple sclerosis is hampered by poor survival of donor oligodendrocyte cell preparations, resulting in limited therapeutic outcomes. Excessive cell death leads to the release of intracellular alloantigens, which likely exacerbate local inflammation and may predispose the graft to eventual rejection. Here, we engineered innovative cell-instructive shear-thinning hydrogels (STHs) with tunable viscoelasticity and bioactivity for minimally invasive delivery of primary human oligodendrocyte progenitor cells (hOPCs) to the brain of a shiverer/rag2 mouse, a model of congenital hypomyelinating disease. The STHs enabled immobilization of prosurvival signals, including a recombinantly designed bidomain peptide and platelet-derived growth factor. Notably, STHs reduced the death rate of hOPCs significantly, promoted the production of myelinating oligodendrocytes, and enhanced myelination of the mouse brain 12 weeks post-implantation. Our results demonstrate the potential of STHs loaded with biological cues to improve cell therapies for the treatment of devastating myelopathies.

The tardigrade-derived mitochondrial abundant heat soluble protein improves adipose-derived stem cell survival against representative stressors

Human adipose-derived stem cell (ASC) grafts have emerged as a powerful tool in regenerative medicine. However, ASC therapeutic potential is hindered by stressors throughout their use. Here we demonstrate the transgenic expression of the tardigrade-derived mitochondrial abundant heat soluble (MAHS) protein for improved ASC resistance to metabolic, mitochondrial, and injection shear stress. In vitro, MAHS-expressing ASCs demonstrate up to 61% increased cell survival following 72 h of incubation in phosphate buffered saline containing 20% media. Following up to 3.5% DMSO exposure for up to 72 h, a 14-49% increase in MAHS-expressing ASC survival was observed. Further, MAHS expression in ASCs is associated with up to 39% improved cell viability following injection through clinically relevant 27-, 32-, and 34-gauge needles. Our results reveal that MAHS expression in ASCs supports survival in response to a variety of common stressors associated with regenerative therapies, thereby motivating further investigation into MAHS as an agent for stem cell stress resistance. However, differentiation capacity in MAHS-expressing ASCs appears to be skewed in favor of osteogenesis over adipogenesis. Specifically, activity of the early bone formation marker alkaline phosphatase is increased by 74% in MAHS-expressing ASCs following 14 days in osteogenic media. Conversely, positive area of the neutral lipid droplet marker BODIPY is decreased by up to 10% in MAHS-transgenic ASCs following 14 days in adipogenic media. Interestingly, media supplementation with up to 40 mM glucose is sufficient to restore adipogenic differentiation within 14 days, prompting further analysis of mechanisms underlying interference between MAHS and differentiation processes.

Fine Tuning Mesenchymal Stromal Cells - Code For Mitigating Kidney Diseases

Kidney Disease (KD), has a high global prevalence and accounts for one of the most prominent causes of morbidity and mortality in the twenty-first century. Despite the advances in our understanding of its pathophysiology, the only available therapy options are dialysis and kidney transplantation. Mesenchymal stem cells (MSCs) have proven to be a viable choice for KD therapy due to their antiapoptotic, immunomodulatory, antioxidative, and pro-angiogenic activities. However, the low engraftment, low survival rate, diminished paracrine ability, and delayed delivery of MSCs are the major causes of the low clinical efficacy. A number of preconditioning regimens are being tested to increase the therapeutic capabilities of MSCs. In this review, we highlight the various strategies to prime MSCs and their protective effects in kidney diseases.

Recent Advances in Alginate-Based Hydrogels for Cell Transplantation Applications

With its exceptional biocompatibility, alginate emerged as a highly promising biomaterial for a large range of applications in regenerative medicine. Whether in the form of microparticles, injectable hydrogels, rigid scaffolds, or bioinks, alginate provides a versatile platform for encapsulating cells and fostering an optimal environment to enhance cell viability. This review aims to highlight recent studies utilizing alginate in diverse formulations for cell transplantation, offering insights into its efficacy in treating various diseases and injuries within the field of regenerative medicine.

Andrographolide induced heme oxygenase-1 expression in MSC-like cells isolated from rat bone marrow exposed to environmental stress

BACKGROUND AND OBJECTIVES

Mesenchymal stem cells (MSC-like cells) are the most important stem cells that are used in transplantation clinically in various applications. The survival rate of MSC-like cells is strongly reduced due to adverse conditions in the microenvironment of transplantation, including environmental stress. Heme oxygenase-1 (HO-1) is a member of the heat shock protein, as well as a stress-induced enzyme, present throughout the body. The present study was conducted to investigate the effect of andrographolide, an active derivative from andrographolide paniculate, on HO-1 expression in mesenchymal stem cells derived from rat bone marrow.

MATERIALS AND METHODS

The rat bone marrow-derived mesenchymal stem cells (BMSC-like cells) were extracted and proliferated in several passages. The identity of MSC-like cells was confirmed by morphological observations and differential tests. The flow cytometry method was used to verify the MSC-specific markers. Isolated MSC-like cells were treated with different concentrations of andrographolide and then exposed to environmental stress. Cell viability was assessed using the MTT colorimetric assay. A real-time PCR technique was employed to evaluate the expression level of HO-1 in the treated MSC-like cells.

RESULTS

Isolated MSC-like cells demonstrated fibroblast-like morphology. These cells in different culture mediums differentiated into osteocytes and adipocytes and were identified using alizarin red and oil red staining, respectively. As well, MSC-like cells were verified by the detection of CD105 surface antigen and the absence of CD14 and CD45 antigens. The results of the MTT assay showed that the pre-treatment of MSC-like cells with andrographolide concentration independently increased the viability and resistance of these cells to environmental stress caused by hydrogen peroxide and serum deprivation (SD). Real-time PCR findings indicated a significant increase in HO-1 gene expression in the andrographolide-receiving groups (p < 0.01).

CONCLUSION

Our results suggest that andrographolide creates a promising strategy for enhancing the quality of cell therapy by increasing the resistance of MSC-like cells to environmental stress and inducing the expression of HO-1.

Acceleration of a delayed healing wound repair model in diabetic rats by additive impacts of photobiomodulation plus conditioned medium of adipose-derived stem cells

Purpose

This study aimed to investigate the effects of photobiomodulation (PBM) and conditioned medium (CM) derived from human adipose-derived stem cells (h-ASCs), both individually and in combination, on the maturation stage of an ischemic infected delayed healing wound model (IIDHWM) in type I diabetic (TIDM) rats.

Methods

The study involved the extraction of h-ASCs from donated fat, assessment of their immunophenotypic markers, cell culture, and extraction and concentration of CM from cultured 1 × 10^6 h-ASCs. TIDM was induced in 24 male adult rats, divided into four groups: control, CM group, PBM group (80 Hz, 0.2 J/cm2, 890 nm), and rats receiving both CM and PBM. Clinical and laboratory evaluations were conducted on days 4, 8, and 16, and euthanasia was performed using CO2 on day 16. Tensiometrical and stereological examinations were carried out using two wound samples from each rat.

Results

Across all evaluated factors, including wound closure ratio, microbiological, tensiometrical, and stereological parameters, similar patterns were observed. The outcomes of CM + PBM, PBM, and CM treatments were significantly superior in all evaluated parameters compared to the control group (p = 0.000 for all). Both PBM and CM + PBM treatments showed better tensiometrical and stereological results than CM alone (almost all, p = 0.000), and CM + PBM outperformed PBM alone in almost all aspects (p = 0.000). Microbiologically, both CM + PBM and PBM exhibited fewer colony-forming units (CFU) than CM alone (both, p = 0.000).

Conclusion

PBM, CM, and CM + PBM interventions substantially enhanced the maturation stage of the wound healing process in IIDHWM of TIDM rats by mitigating the inflammatory response and reducing CFU count. Moreover, these treatments promoted new tissue formation in the wound bed and improved wound strength. Notably, the combined effects of CM + PBM surpassed the individual effects of CM and PBM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01285-3.

Hypoxic Preconditioning Enhances Cellular Viability and Migratory Ability: Role of DANCR/miR-656-3p/HIF-1α Axis in Placental Mesenchymal Stem Cells

Preeclampsia (PE) is a common complication of pregnancy characterized by new-onset hypertension, albuminuria, or end-stage organ dysfunction, which is seriously harmful to maternal and infant health. Mesenchymal stem cells (MSCs) are pluripotent stem cells derived from extraembryonic mesoderm. They have the potential for self-renewal, multidirectional differentiation, immunomodulation, and tissue regeneration. Several in vivo and in vitro experiments have confirmed that MSCs can delay the pathological progression of PE and improve maternal and fetal outcomes. However, the major limitations in the application of MSCs are their low-survival rates in ischemic and hypoxic disease areas after transplantation and their low rate of successful migration to the diseased regions. Therefore, enhancing cell viability and migration ability of MSCs in both ischemic and anoxic environments is important. This study aimed to investigate the effects of hypoxic preconditioning on the viability and migration ability of placental mesenchymal stem cells (PMSCs) and their underlying mechanisms. In this study, we found that hypoxic preconditioning enhanced the viability and migration ability of PMSCs, increased the expression of DANCR and hypoxia-inducible factor-1α (HIF-1α), and decreased the expression of miR-656-3p in PMSCs. Inhibiting the expression of HIF-1α and DACNR in PMSCs under hypoxia can inhibit the promotive effect of hypoxic preconditioning on viability and migration ability. In addition, RNA pull down and double luciferase assays confirmed that miR-656-3p could directly bind to DANCR and HIF-1α. In conclusion, our study showed that hypoxia could promote the viability and migration ability of PMSCs through the DANCR/miR-656-3p/HIF-1α axis.

Application of locally responsive design of biomaterials based on microenvironmental changes in myocardial infarction

Morbidity and mortality caused by acute myocardial infarction (AMI) are on the rise, posing a grave threat to the health of the general population. Up to now, interventional, surgical, and pharmaceutical therapies have been the main treatment methods for AMI. Effective and timely reperfusion therapy decreases mortality, but it cannot stimulate myocardial cell regeneration or reverse ventricular remodeling. Cell therapy, gene therapy, immunotherapy, anti-inflammatory therapy, and several other techniques are utilized by researchers to improve patients' prognosis. In recent years, biomaterials for AMI therapy have become a hot spot in medical care. Biomaterials furnish a microenvironment conducive to cell growth and deliver therapeutic factors that stimulate cell regeneration and differentiation. Biomaterials adapt to the complex microenvironment and respond to changes in local physical and biochemical conditions. Therefore, environmental factors and material properties must be taken into account when designing biomaterials for the treatment of AMI. This article will review the factors that need to be fully considered in the design of biological materials.

Spheroid Formation and Recovery Using Superhydrophobic Coating for Regenerative Purposes

Cell therapies commonly pursue tissue stimulation for regenerative purposes by replacing cell numbers or supplying for functional deficiencies. To this aim, monodispersed cells are usually transplanted for incorporation by local injection. The limitations of this strategy include poor success associated with cell death, insufficient retention, or cell damage due to shear forces associated with the injection. Spheroids have recently emerged as a model that mimics an in vivo environment with more representative cell-to-cell interactions and better intercellular communication. Nevertheless, cost-effective and lab friendly fabrication and effectively performed recovery are challenges that restrict the broad application of spheroids. In this work, glass surfaces were modified with an environmentally friendly superhydrophobic coating. The superhydrophobic surfaces were used for the 3D spheroid preparation of fibroblasts (3T3 cell line) and keratinocytes (HaCaT cell line). The effectiveness of the spheroids to be recovered and grown under 2D culture conditions was evaluated. The morphology of the migrated cells from the 3D spheroids was characterized at the nano-microscale through 3D profilometry. The results demonstrated improved adhesion and proliferation in the migrated cells, both advanced properties for regenerative applications.

Nanowired human cardiac organoid transplantation enables highly efficient and effective recovery of infarcted hearts

Human cardiac organoids hold remarkable potential for cardiovascular disease modeling and human pluripotent stem cell-derived cardiomyocyte (hPSC-CM) transplantation. Here, we show cardiac organoids engineered with electrically conductive silicon nanowires (e-SiNWs) significantly enhance the therapeutic efficacy of hPSC-CMs to treat infarcted hearts. We first demonstrated the biocompatibility of e-SiNWs and their capacity to improve cardiac microtissue engraftment in healthy rat myocardium. Nanowired human cardiac organoids were then engineered with hPSC-CMs, nonmyocyte supporting cells, and e-SiNWs. Nonmyocyte supporting cells promoted greater ischemia tolerance of cardiac organoids, and e-SiNWs significantly improved electrical pacing capacity. After transplantation into ischemia/reperfusion-injured rat hearts, nanowired cardiac organoids significantly improved contractile development of engrafted hPSC-CMs, induced potent cardiac functional recovery, and reduced maladaptive left ventricular remodeling. Compared to contemporary studies with an identical injury model, greater functional recovery was achieved with a 20-fold lower dose of hPSC-CMs, revealing therapeutic synergy between conductive nanomaterials and human cardiac organoids for efficient heart repair.

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

BACKGROUND

Critical 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.

METHODS

This 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.

RESULTS

All 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.

CONCLUSION

The 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.

Recent Advances in Tissue-Engineered Cardiac Scaffolds-The Progress and Gap in Mimicking Native Myocardium Mechanical Behaviors

Heart failure is the leading cause of death in the US and worldwide. Despite modern therapy, challenges remain to rescue the damaged organ that contains cells with a very low proliferation rate after birth. Developments in tissue engineering and regeneration offer new tools to investigate the pathology of cardiac diseases and develop therapeutic strategies for heart failure patients. Tissue -engineered cardiac scaffolds should be designed to provide structural, biochemical, mechanical, and/or electrical properties similar to native myocardium tissues. This review primarily focuses on the mechanical behaviors of cardiac scaffolds and their significance in cardiac research. Specifically, we summarize the recent development of synthetic (including hydrogel) scaffolds that have achieved various types of mechanical behavior-nonlinear elasticity, anisotropy, and viscoelasticity-all of which are characteristic of the myocardium and heart valves. For each type of mechanical behavior, we review the current fabrication methods to enable the biomimetic mechanical behavior, the advantages and limitations of the existing scaffolds, and how the mechanical environment affects biological responses and/or treatment outcomes for cardiac diseases. Lastly, we discuss the remaining challenges in this field and suggestions for future directions to improve our understanding of mechanical control over cardiac function and inspire better regenerative therapies for myocardial restoration.

Apoptotic Vesicles Regulate Bone Metabolism via the miR1324/SNX14/SMAD1/5 Signaling Axis

Mesenchymal stem cells (MSCs) are widely used in the treatment of diseases. After their in vivo application, MSCs undergo apoptosis and release apoptotic vesicles (apoVs). This study investigates the role of apoVs derived from human bone marrow mesenchymal stem cells (hBMMSCs) in bone metabolism and the molecular mechanism of the observed effects. The results show that apoVs can promote osteogenesis and inhibit osteoclast formation in vitro and in vivo. ApoVs may therefore attenuate the bone loss caused by primary and secondary osteoporosis and stimulate bone regeneration in areas of bone defect. The mechanisms responsible for apoV-induced bone regeneration include the release of miR1324, which inhibit expression of the target gene Sorting Nexin 14 (SNX14) and thus activate the SMAD1/5 pathway in target cells. Given that MSC-derived apoVs are easily obtained and stored, with low risks of immunological rejection and neoplastic transformation, The findings suggest a novel therapeutic strategy to treat bone loss, including via cell-free approaches to bone tissue engineering.

Temporary induction of hypoxic adaptations by preconditioning fails to enhance Schwann cell transplant survival after spinal cord injury

Hypoxic preconditioning is protective in multiple models of injury and disease, but whether it is beneficial for cells transplanted into sites of spinal cord injury (SCI) is largely unexplored. In this study, we analyzed whether hypoxia-related preconditioning protected Schwann cells (SCs) transplanted into the contused thoracic rat spinal cord. Hypoxic preconditioning was induced in SCs prior to transplantation by exposure to either low oxygen (1% O2 ) or pharmacological agents (deferoxamine or adaptaquin). All preconditioning approaches induced hypoxic adaptations, including increased expression of HIF-1α and its target genes. These adaptations, however, were transient and resolved within 24 h of transplantation. Pharmacological preconditioning attenuated spinal cord oxidative stress and enhanced transplant vascularization, but it did not improve either transplanted cell survival or recovery of sensory or motor function. Together, these experiments show that hypoxia-related preconditioning is ineffective at augmenting either cell survival or the functional outcomes of SC-SCI transplants. They also reveal that the benefits of hypoxia-related adaptations induced by preconditioning for cell transplant therapies are not universal.

Engineered tissue vascularization and engraftment depends on host model

Developing vascular networks that integrate with the host circulation and support cells engrafted within engineered tissues remains a key challenge in tissue engineering. Most previous work in this field has focused on developing new methods to build human vascular networks within engineered tissues prior to their implant in vivo, with substantively less attention paid to the role of the host in tissue vascularization and engraftment. Here, we assessed the role that different host animal models and anatomic implant locations play in vascularization and cardiomyocyte survival within engineered tissues. We found major differences in the formation of graft-derived blood vessels and survival of cardiomyocytes after implantation of identical tissues in immunodeficient athymic nude mice versus rats. Athymic mice supported robust guided vascularization of human microvessels carrying host blood but relatively sparse cardiac grafts within engineered tissues, regardless of implant site. Conversely, athymic rats produced substantive inflammatory changes that degraded grafts (abdomen) or disrupted vascular patterning (heart). Despite disrupted vascular patterning, athymic rats supported > 3-fold larger human cardiomyocyte grafts compared to athymic mice. This work demonstrates the critical importance of the host for vascularization and engraftment of engineered tissues, which has broad translational implications across regenerative medicine.

Fat Juice: A Novel Approach on the Usage and Preparation of Adipose Tissue By-Products

BACKGROUND

Adipose tissue is considered to be naturally rich in a range of bioactive substances that may be extracted directly for therapeutic use without the need for cell isolation or culture.

OBJECTIVES

The aim of this study was to introduce a novel approach that utilizes stromal vascular fraction in conjunction with fat extract, termed "fat juice," and to perform a comprehensive biochemical analysis in relation to the potential clinical relevance of this new combination.

METHODS

A total of 11 samples of fat juice from the abdominal lipoaspirate were extracted from 11 healthy patients and analyzed in terms of the quantity and viability of stem cells, the presence and quantification of connective tissue fibers on histopathologic examination, and the levels of interleukin-6, mannose receptor C type 1, and vascular endothelial growth factor measured by enzyme-linked immunosorbent assay.

RESULTS

Total stem cell amounts ranged from 0.14 × 105 to 1.31 × 105, and cell viability rates varied between 20% and 67.9%. Interleukin-6 protein and vascular endothelial growth factor expressions were highest in Sample 3, while staining intensity was highest in Sample 4. For collagen I, collagen III, and elastin, the highest expressions were observed in Samples 4 and 8, in Sample 3, and in Samples 2 and 4, respectively.

CONCLUSIONS

Fat juice provides an easy-to-inject concentration of adipocyte/preadipocytes, red blood cells, adipose-derived stem cells, endothelial-derived cells, and cell residues. Prepared through an easy isolation process enabling abundant availability, fat juice seems to be an effective skin quality enhancer with potential for widespread use in the fields of plastic surgery, dermatology, and aesthetic/regenerative medicine.

Pericardial Grafting of Cardiac Progenitor Cells in Self-Assembling Peptide Scaffold Improves Cardiac Function After Myocardial Infarction

Many studies have explored cardiac progenitor cell (CPC) therapy for heart disease. However, optimal scaffolds are needed to ensure the engraftment of transplanted cells. We produced a three-dimensional hydrogel scaffold (CPC-PRGmx) in which high-viability CPCs were cultured for up to 8 weeks. CPC-PRGmx contained an RGD peptide-conjugated self-assembling peptide with insulin-like growth factor-1 (IGF-1). Immediately after creating myocardial infarction (MI), we transplanted CPC-PRGmx into the pericardial space on to the surface of the MI area. Four weeks after transplantation, red fluorescent protein-expressing CPCs and in situ hybridization analysis in sex-mismatched transplantations revealed the engraftment of CPCs in the transplanted scaffold (which was cellularized with host cells). The average scar area of the CPC-PRGmx-treated group was significantly smaller than that of the non-treated group (CPC-PRGmx-treated group = 46 ± 5.1%, non-treated MI group = 59 ± 4.5%; p < 0.05). Echocardiography showed that the transplantation of CPC-PRGmx improved cardiac function and attenuated cardiac remodeling after MI. The transplantation of CPCs-PRGmx promoted angiogenesis and inhibited apoptosis, compared to the untreated MI group. CPCs-PRGmx secreted more vascular endothelial growth factor than CPCs cultured on two-dimensional dishes. Genetic fate mapping revealed that CPC-PRGmx-treated mice had more regenerated cardiomyocytes than non-treated mice in the MI area (CPC-PRGmx-treated group = 0.98 ± 0.25%, non-treated MI group = 0.25 ± 0.04%; p < 0.05). Our findings reveal the therapeutic potential of epicardial-transplanted CPC-PRGmx. Its beneficial effects may be mediated by sustainable cell viability, paracrine function, and the enhancement of de novo cardiomyogenesis.

Transfer-Tattoo-Like Cell-Sheet Delivery Induced by Interfacial Cell Migration

A direct transfer of a cell sheet from a culture surface to a target tissue is introduced. Commercially available, flexible parylene is used as the culture surface, and it is proposed that the UV-treated parylene offers adequate and intermediate levels of cell adhesiveness for both the stable cell attachment during culture and for the efficient cell transfer to a target surface. The versatility of this cell-transfer process is demonstrated with various cell types, including MRC-5, HDFn, HULEC-5a, MC3T3-E1, A549, C2C12 cells, and MDCK-II cells. The novel cell-sheet engineering is based on a mechanism of interfacial cell migration between two surfaces with different adhesion preferences. Monitoring of cytoskeletal dynamics and drug treatments during the cell-transfer process reveals that the interfacial cell migration occurs by utilizing the existing transmembrane proteins on the cell surface to bind to the targeted surface. The re-establishment and reversal of cell polarity after the transfer process are also identified. Its unique capabilities of 3D multilayer stacking, freeform design, and curved surface application are demonstrated. Finally, the therapeutic potential of the cell-sheet delivery system is demonstrated by applying it to cutaneous wound healing and skin-tissue regeneration in mice models.

Strategies to capitalize on cell spheroid therapeutic potential for tissue repair and disease modeling

Cell therapies offer a tailorable, personalized treatment for use in tissue engineering to address defects arising from trauma, inefficient wound repair, or congenital malformation. However, most cell therapies have achieved limited success to date. Typically injected in solution as monodispersed cells, transplanted cells exhibit rapid cell death or insufficient retention at the site, thereby limiting their intended effects to only a few days. Spheroids, which are dense, three-dimensional (3D) aggregates of cells, enhance the beneficial effects of cell therapies by increasing and prolonging cell-cell and cell-matrix signaling. The use of spheroids is currently under investigation for many cell types. Among cells under evaluation, spheroids formed of mesenchymal stromal cells (MSCs) are particularly promising. MSC spheroids not only exhibit increased cell survival and retained differentiation, but they also secrete a potent secretome that promotes angiogenesis, reduces inflammation, and attracts endogenous host cells to promote tissue regeneration and repair. However, the clinical translation of spheroids has lagged behind promising preclinical outcomes due to hurdles in their formation, instruction, and use that have yet to be overcome. This review will describe the current state of preclinical spheroid research and highlight two key examples of spheroid use in clinically relevant disease modeling. It will highlight techniques used to instruct the phenotype and function of spheroids, describe current limitations to their use, and offer suggestions for the effective translation of cell spheroids for therapeutic treatments.

Photobiomodulation in 3D tissue engineering

SIGNIFICANCE

The method of photobiomodulation (PBM) has been used in medicine for a long time to promote anti-inflammation and pain-resolving processes in different organs and tissues. PBM triggers numerous cellular pathways including stimulation of the mitochondrial respiratory chain, alteration of the cytoskeleton, cell death prevention, increasing proliferative activity, and directing cell differentiation. The most effective wavelengths for PBM are found within the optical window (750 to 1100 nm), in which light can permeate tissues and other water-containing structures to depths of up to a few cm. PBM already finds its applications in the developing fields of tissue engineering and regenerative medicine. However, the diversity of three-dimensional (3D) systems, irradiation sources, and protocols intricate the PBM applications.

AIM

We aim to discuss the PBM and 3D tissue engineered constructs to define the fields of interest for PBM applications in tissue engineering.

APPROACH

First, we provide a brief overview of PBM and the timeline of its development. Then, we discuss the optical properties of 3D cultivation systems and important points of light dosimetry. Finally, we analyze the cellular pathways induced by PBM and outcomes observed in various 3D tissue-engineered constructs: hydrogels, scaffolds, spheroids, cell sheets, bioprinted structures, and organoids.

RESULTS

Our summarized results demonstrate the great potential of PBM in the stimulation of the cell survival and viability in 3D conditions. The strategies to achieve different cell physiology states with particular PBM parameters are outlined.

CONCLUSIONS

PBM has already proved itself as a convenient and effective tool to prevent drastic cellular events in the stress conditions. Because of the poor viability of cells in scaffolds and the convenience of PBM devices, 3D tissue engineering is a perspective field for PBM applications.

Strategies to improve the therapeutic effect of pluripotent stem cell-derived cardiomyocytes on myocardial infarction

Myocardial infarction (MI) is a common cardiovascular disease caused by permanent loss of cardiomyocytes and the formation of scar tissue due to myocardial ischemia. Mammalian cardiomyocytes lose their ability to proliferate almost completely in adulthood and are unable to repair the damage caused by MI. Therefore, transplantation of exogenous cells into the injured area for treatment becomes a promising strategy. Pluripotent stem cells (PSCs) have the ability to proliferate and differentiate into various cellular populations indefinitely, and pluripotent stem cell-derived cardiomyocytes (PSC-CMs) transplanted into areas of injury can compensate for part of the injuries and are considered to be one of the most promising sources for cell replacement therapy. However, the low transplantation rate and survival rate of currently transplanted PSC-CMs limit their ability to treat MI. This article focuses on the strategies of current research for improving the therapeutic efficacy of PSC-CMs, aiming to provide some inspiration and ideas for subsequent researchers to further enhance the transplantation rate and survival rate of PSC-CMs and ultimately improve cardiac function.

Compatibility and function of human induced pluripotent stem cell derived cardiomyocytes on an electrospun nanofibrous scaffold, generated from an ionomeric polyurethane composite

Synthetic scaffolds are needed for generating organized neo-myocardium constructs to promote functional tissue repair. This study investigated the biocompatibility of an elastomeric electrospun degradable polar/hydrophobic/ionic polyurethane (D-PHI) composite scaffold with human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The composite material was electrospun to generate scaffolds, with nanofibres oriented in aligned or random directions. These features enabled the authors to evaluate the effect of characteristic elements which mimic that of the native extracellular matrix (alignment, chemical heterogeneity, and fiber topography) on hiPSC-CMs activity. The functional nature of the hiPSC-CM cultured on gelatin and Matrigel-coated scaffolds were assessed, investigating the influence of protein interactions with the synthetic substrate on subsequent cell phenotype. After 7 days of culture, high hiPSC-CM viability was observed on the scaffolds. The cells on the aligned scaffold were elongated and demonstrated aligned sarcomeres that oriented parallel to the direction of the fibers, while the cells on random scaffolds and a tissue culture polystyrene (TCPS) control did not exhibit such an organized morphology. The hiPSC-CMs cultured on the scaffolds and TCPS expressed similar levels of cardiac troponin-T, but there was a higher expression of ventricular myosin light chain-2 on the D-PHI composite scaffolds versus TCPS, indicating a higher proportion of hiPSC-CM exhibiting a ventricular cardiomyocyte like phenotype. Within 7 days, the hiPSC-CMs on aligned scaffolds and TCPS beat synchronously and had similar conductive velocities. These preliminary results show that aligned D-PHI elastomeric scaffolds allow hiPSC-CMs to demonstrate important cardiomyocytes characteristics, critical to enabling their future potential use for cardiac tissue regeneration.

Stem Cell-Based Therapy: A Promising Treatment for Diabetic Foot Ulcer

Diabetic foot ulcer (DFU) is a severe complication of diabetes and a challenging medical condition. Conventional treatments for DFU have not been effective enough to reduce the amputation rates, which urges the need for additional treatment. Stem cell-based therapy for DFU has been investigated over the past years. Its therapeutic effect is through promoting angiogenesis, secreting paracrine factors, stimulating vascular differentiation, suppressing inflammation, improving collagen deposition, and immunomodulation. It is controversial which type and origin of stem cells, and which administration route would be the most optimal for therapy. We reviewed the different types and origins of stem cells and routes of administration used for the treatment of DFU in clinical and preclinical studies. Diabetes leads to the impairment of the stem cells in the diseased patients, which makes it less ideal to use autologous stem cells, and requires looking for a matching donor. Moreover, angioplasty could be complementary to stem cell therapy, and scaffolds have a positive impact on the healing process of DFU by stem cell-based therapy. In short, stem cell-based therapy is promising in the field of regenerative medicine, but more studies are still needed to determine the ideal type of stem cells required in therapy, their safety, proper dosing, and optimal administration route.

In situ delivery of apoptotic bodies derived from mesenchymal stem cells via a hyaluronic acid hydrogel: A therapy for intrauterine adhesions

Stem cell-based and stem cell-derived exosome-based therapies have shown promising potential for endometrial regeneration and the clinical treatment of intrauterine adhesions (IUAs). Evidence shows that apoptosis occurs in a majority of grafted stem cells, and apoptotic bodies (ABs) play a critical role in compensatory tissue regeneration. However, the therapeutic potential of AB-based therapy and its mechanism have not been explored in detail. Here, a cell-free therapeutic strategy was developed by incorporating mesenchymal stem cell-derived ABs into a hyaluronic acid (HA) hydrogel to achieve endometrial regeneration and fertility restoration. Specifically, we found that the ABs could induce macrophage immunomodulation, cell proliferation, and angiogenesis in vitro. The HA hydrogel promoted the retention of ABs and facilitated their continuous release. In a murine model of acute endometrial damage and a rat model of IUAs, in situ injection of the AB-laden HA hydrogel could efficiently reduce fibrosis and promote endometrial regeneration, resulting in the fertility restoration. Consequently, ABs show good potential as therapeutic vesicles, and the AB-laden HA hydrogel appears to be a clinically feasible and cell-free alternative for endometrial regeneration and IUA treatment.

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Human umbilical cord derived apoptotic bodies induce macrophage immunomodulation, cell proliferation and angiogenesis

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A strategy of apoptotic bodies associated with hyaluronic acid hydrogel promotes apoptotic bodies retention and continuous release

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The implantation of the apoptotic body-laden hyaluronic acid hydrogel into uterine cavity effectively promoted endometrial regeneration and fertility restoration in a rodent model of intrauterine adhesion

Pre-Conditioning Methods and Novel Approaches with Mesenchymal Stem Cells Therapy in Cardiovascular Disease

Transplantation of mesenchymal stem cells (MSCs) in the setting of cardiovascular disease, such as heart failure, cardiomyopathy and ischemic heart disease, has been associated with good clinical outcomes in several trials. A reduction in left ventricular remodeling, myocardial fibrosis and scar size, an improvement in endothelial dysfunction and prolonged cardiomyocytes survival were reported. The regenerative capacity, in addition to the pro-angiogenic, anti-apoptotic and anti-inflammatory effects represent the main target properties of these cells. Herein, we review the different preconditioning methods of MSCs (hypoxia, chemical and pharmacological agents) and the novel approaches (genetically modified MSCs, MSC-derived exosomes and engineered cardiac patches) suggested to optimize the efficacy of MSC therapy.

Stem Cell Transplantation Therapy and Neurological Disorders: Current Status and Future Perspectives

Neurodegenerative diseases are a global health issue with inadequate therapeutic options and an inability to restore the damaged nervous system. With advances in technology, health scientists continue to identify new approaches to the treatment of neurodegenerative diseases. Lost or injured neurons and glial cells can lead to the development of several neurological diseases, including Parkinson's disease, stroke, and multiple sclerosis. In recent years, neurons and glial cells have successfully been generated from stem cells in the laboratory utilizing cell culture technologies, fueling efforts to develop stem cell-based transplantation therapies for human patients. When a stem cell divides, each new cell has the potential to either remain a stem cell or differentiate into a germ cell with specialized characteristics, such as muscle cells, red blood cells, or brain cells. Although several obstacles remain before stem cells can be used for clinical applications, including some potential disadvantages that must be overcome, this cellular development represents a potential pathway through which patients may eventually achieve the ability to live more normal lives. In this review, we summarize the stem cell-based therapies that have been explored for various neurological disorders, discuss the potential advantages and drawbacks of these therapies, and examine future directions for this field.

Mesenchymal stem cells: A new therapeutic tool for chronic kidney disease

Chronic kidney disease (CKD) has a major impact on public health, which could progress to end-stage kidney disease (ESRD) and consume many medical resources. Currently, the treatment for CKD has many flaws, so more effective treatment tools are urgently required for CKD. Mesenchymal stem cells (MSCs) are primitive cells with self-renewal and proliferation capacity and differentiation potential. Extensive preclinical and clinical data has shown that cell-based therapies using MSCs can modulate immunity, inhibit inflammatory factors, and improve renal function in CKD, suggesting that MSCs have the potential to be a new, effective therapeutic tool for CKD. In this review, we will describe different kinds of MSCs and MSCs products for the treatment of CKD in experimental models and clinical trials, potential signaling pathways, therapeutic efficacy, and critical issues that need to be addressed before therapeutic application in humans.

Stem cell therapy for acute myocardial infarction - focusing on the comparison between Muse cells and mesenchymal stem cells

Rapid percutaneous coronary intervention for acute myocardial infarction (AMI) reduces acute mortality, but there is an urgent need for treatment of left ventricular dysfunction and remodeling after AMI to improve the prognosis. The myocardium itself does not have a high regenerative capacity, and it is important to minimize the loss of cardiomyocytes and maintain the cardiac function after AMI. To overcome these problems, attention has been focused on myocardial regeneration therapy using cells derived from bone marrow. The clinical use of bone marrow stem cells is considered to have low safety concerns based on the experience of using bone marrow transplantation for blood diseases in clinical practice. It has been reported that bone marrow mononuclear cells (BM-MNC) and mesenchymal stem cells (BM-MSC) differentiate into cardiomyocytes both in vitro and in vivo, and they have been considered a promising source for stem cell therapy. To prevent heart failure after human AMI, studies have been conducted to regenerate myocardial tissue by transplanting bone marrow stem cells, such as BM-MSCs and BM-MNCs. Therapies using those cells have been administered to animal models of AMI, and were effective to some extent, but the effect in clinical trials was limited. Recently, it was reported that multilineage-differentiating stress enduring cells (Muse cells), which are endogenous pluripotent stem cells obtainable from various tissues including the bone marrow, more markedly reduced the myocardial infarct size and improved the cardiac function via regeneration of cardiomyocytes and vessels and paracrine effects compared with BM-MSCs. Here, we describe stem cell therapies using conventional BM-MNCs and BM-MSCs, and Muse cells which have potential for clinical use for the treatment of AMI.

Preconditioned human dental pulp stem cells with cerium and yttrium oxide nanoparticles effectively ameliorate diabetic hyperglycemia while combatting hypoxia

The development of efficient insulin producing cells (IPC) induction system is fundamental for the regenerative clinical applications targeting Diabetes Mellitus. This study was set to generate IPC from human dental pulp stem cells (hDPSCs) capable of surviving under hypoxic conditions in vitro and in vivo.

METHODS

hDPSCs were cultured in IPCs induction media augmented with Cerium or Yttrium oxide nanoparticles along with selected growth factors & cytokines. The generated IPC were subjected to hypoxic stress in vitro to evaluate the ability of the nanoparticles to combat hypoxia. Next, they were labelled and implanted into diabetic rats. Twenty eight days later, blood glucose and serum insulin levels, hepatic hexokinase and glucose-6-phosphate dehydrogenase activities were measured. Pancreatic vascular endothelial growth factor (VEGF), pancreatic duodenal homeobox1 (Pdx-1), hypoxia inducible factor 1 alpha (HIF-1α) and Caspase-3 genes expression level were evaluated.

RESULTS

hDPSCs were successfully differentiated into IPCs after incubation with the inductive media enriched with nanoparticles. The generated IPCs released significant amounts of insulin in response to increasing glucose concentration both in vitro & in vivo. The generated IPCs showed up-regulation in the expression levels of anti-apoptotic genes in concomitant with down-regulation in the expression levels of hypoxic, and apoptotic genes. The in vivo study confirmed the homing of PKH-26-labeled cells in pancreas of treated groups. A significant up-regulation in the expression of pancreatic VEGF and PDX-1 genes associated with significant down-regulation in the expression of pancreatic HIF-1α and caspase-3 was evident.

CONCLUSION

The achieved results highlight the promising role of the Cerium & Yttrium oxide nanoparticles in promoting the generation of IPCs that have the ability to combat hypoxia and govern diabetes mellitus.

Cardiac Repair With Echocardiography-Guided Multiple Percutaneous Left Ventricular Intramyocardial Injection of hiPSC-CMs After Myocardial Infarction

Objective: We investigated the potency of cardiac repair based on echocardiography-guided multiple percutaneous left ventricular intramyocardial injection of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) after myocardial infarction (MI).

Methods: Mice with surgically induced MI were randomly divided into three groups (n = 8 in each group) and subjected to echocardiography-guided percutaneous left ventricular infarcted border injection of hiPSC-CMs (single dose; 10 μl 3 × 10⁵ cells) or repeated injections of hiPSC-CMs at post-MI weeks 1 and 2 (multiple doses). The sham group of animals underwent all surgical procedures necessary for MI induction except for ligation. Then 4 weeks after MI, heart function was measured with transthoracic echocardiography. Engraftment was evaluated through the detection of human-specific cardiac troponin T. Infarct size and collagen volume were calculated with Sirius Red/Fast Green staining. Angiogenesis was evaluated with isolectin B4 staining. Cardiac remodeling was evaluated from the cardiomyocyte minimal fiber diameter in the infarcted border zone. Apoptosis was detected via TdT-mediated dUTP Nick-End Labeling (TUNEL) staining in cardiomyocytes from the infarcted border zone.

Results: No mice died after echocardiography-guided percutaneous left ventricular intramyocardial injection. hiPSC-CMs were about nine-fold higher in the multiple-dose group at week 4 compared to the single-dose group. Multiple-dose transplantation was associated with significant improvement in left ventricular function, infarct size, angiogenesis, cardiac remodeling, and cardiomyocyte apoptosis.

Conclusion: Echocardiography-guided multiple percutaneous left ventricular intramyocardial injection is a feasible, satisfactory, repeatable, relatively less invasive, and effective method of delivering cell therapy. The delivery of hiPSC-CMs indicates a novel therapy for MI.

Nanotechnology in cardiac stem cell therapy: cell modulation, imaging and gene delivery

The wide arena of applications opened by nanotechnology is multidimensional. It is already been proven that its prominence can continuously influence human life. The role of stem cells in curing degenerative diseases is another major area of research. Cardiovascular diseases are one of the major causes of death globally. Nanotechnology-assisted stem cell therapy could be used to tackle the challenges faced in the management of cardiovascular diseases. In spite of the positive indications and proven potential of stem cells to differentiate into cardiomyocytes for cardiac repair and regeneration during myocardial infarction, this therapeutic approach still remains in its infancy due to several factors such as non-specificity of injected cells, insignificant survival rate, and low cell retention. Attempts to improve stem cell therapy using nanoparticles have shown some interest among researchers. This review focuses on the major hurdles associated with cardiac stem cell therapy and the role of nanoparticles to overcome the major challenges in this field, including cell modulation, imaging, tracking and gene delivery.

This review summarizes the potential challenges present in cardiac stem cell therapy and the major role of nanotechnology to overcome these challenges including cell modulation, tracking and imaging of stem cells.

Platelet extracellular vesicles enhance the proangiogenic potential of adipose-derived stem cells in vivo and in vitro

BACKGROUND

Adipose-derived mesenchymal stem cells (ADSC)-based therapy is an outstanding treatment strategy for ischaemic disease. However, the therapeutic efficacy of this strategy is not ideal due to the poor paracrine function and low survival rate of ADSCs in target regions. Platelet extracellular vesicles (PEVs) are nanoparticles derived from activated platelets that can participate in communication between cells. Accumulating evidence indicates that PEVs can regulate the biological functions of several cell lines. In the present study, we aimed to investigate whether PEVs can modulate the proangiogenic potential of ADSCs in vitro and in vivo.

METHODS

PEVs were identified using scanning electron microscope (SEM), flow cytometry (FCM) and nanoparticle tracking analysis (NTA). The CCK8 assay was performed to detect proliferation of cells. Transwell and wound healing assays were performed to verify migration capacity of cells. AnnexinV-FITC/PI apoptosis kit and live/dead assay were performed to assess ADSCs apoptosis under Cocl₂-induced hypoxia condition. The underlying mechanisms by which PEVs affected ADSCs were explored using real time-PCR(RT-PCR) and Western blot. In addition, matrigel plug assays were conducted and mouse hindlimb ischaemic models were established to investigate the proangiogenic potential of PEV-treated ADSCs in vivo.

RESULTS

We demonstrated that ADSC could internalize PEVs, which lead to a series of biological reactions. In vitro, dose-dependent effects of PEVs on ADSC proliferation, migration and antiapoptotic capacity were observed. Western blotting results suggested that multiple proteins such as ERK, AKT, FAK, Src and PLCγ1 kinase may contribute to these changes. Furthermore, PEVs induced upregulation of several growth factors expression in ADSCs and amplified the proliferation, migration and tube formation of HUVECs induced by ADSC conditioned medium (CM). In in vivo experiments, compared with control ADSCs, the injection of PEV-treated ADSCs resulted in more vascularization in matrigel plugs, attenuated tissue degeneration and increased blood flow and capillary density in ischaemic hindlimb tissues.

CONCLUSION

Our data demonstrated that PEVs could enhance the proangiogenic potential of ADSCs in mouse hindlimb ischaemia. The major mechanisms of this effect included the promotion of ADSC proliferation, migration, anti-apoptosis ability and paracrine secretion.

Translational insights into stem cell preconditioning: From molecular mechanisms to preclinical applications

Cell-based therapy (CBT) is a revolutionary approach for curing a variety of degenerative diseases. Stem cell-based regenerative medicine is a novel strategy for treating tissue damages regarding stem cells unique properties such as differentiation potential, paracrine impacts, and self-renewal ability. However, the current cell-based treatments encounter considerable challenges to be translated into clinical practice, including low cell survival, migration, and differentiation rate of transplanted stem cells. The poor stem cell therapy outcomes mainly originate from the unfavorable condition of damaged tissues for transplanted stem cells. The promising method of preconditioning improves cell resistance against the host environment's stress by imposing certain conditions similar to the harsh microenvironment of the damaged tissues on the transplanted stem cells. Various pharmacological, biological, and physical inducers are able to establish preconditioning. In addition to their known pharmacological effects on tissues and cells, these preconditioning agents improve cell biological aspects such as cell survival, proliferation, differentiation, migration, immunomodulation, paracrine impacts, and angiogenesis. This review focuses on different protocols and inducers of preconditioning along with underlying molecular mechanisms of their effects on stem cell behavior. Moreover, preclinical applications of preconditioned stem cells in various damaged organs such as heart, lung, brain, bone, cartilage, liver, and kidney are discussed with prospects of their translation into the clinic.

Bioengineering the Cardiac Conduction System: Advances in Cellular, Gene, and Tissue Engineering for Heart Rhythm Regeneration

Heart rhythm disturbances caused by different etiologies may affect pediatric and adult patients with life-threatening consequences. When pharmacological therapy is ineffective in treating the disturbances, the implantation of electronic devices to control and/or restore normal heart pacing is a unique clinical management option. Although these artificial devices are life-saving, they display many limitations; not least, they do not have any capability to adapt to somatic growth or respond to neuroautonomic physiological changes. A biological pacemaker could offer a new clinical solution for restoring heart rhythms in the conditions of disorder in the cardiac conduction system. Several experimental approaches, such as cell-based, gene-based approaches, and the combination of both, for the generation of biological pacemakers are currently established and widely studied. Pacemaker bioengineering is also emerging as a technology to regenerate nodal tissues. This review analyzes and summarizes the strategies applied so far for the development of biological pacemakers, and discusses current translational challenges toward the first-in-human clinical application.

Neural Stem Cells for Early Ischemic Stroke

Clinical treatments for ischemic stroke are limited. Neural stem cell (NSC) transplantation can be a promising therapy. Clinically, ischemia and subsequent reperfusion lead to extensive neurovascular injury that involves inflammation, disruption of the blood-brain barrier, and brain cell death. NSCs exhibit multiple potentially therapeutic actions against neurovascular injury. Currently, tissue plasminogen activator (tPA) is the only FDA-approved clot-dissolving agent. While tPA’s thrombolytic role within the vasculature is beneficial, tPA’s non-thrombolytic deleterious effects aggravates neurovascular injury, restricting the treatment time window (time-sensitive) and tPA eligibility. Thus, new strategies are needed to mitigate tPA’s detrimental effects and quickly mediate vascular repair after stroke. Up to date, clinical trials focus on the impact of stem cell therapy on neuro-restoration by delivering cells during the chronic stroke stage. Also, NSCs secrete factors that stimulate endogenous repair mechanisms for early-stage ischemic stroke. This review will present an integrated view of the preclinical perspectives of NSC transplantation as a promising treatment for neurovascular injury, with an emphasis on early-stage ischemic stroke. Further, this will highlight the impact of early sub-acute NSC delivery on improving short-term and long-term stroke outcomes.

Plasma-polymerized pericyte patches improve healing of murine wounds through increased angiogenesis and reduced inflammation

Pericytes have the potential to be developed as a cell therapy for the treatment of wounds; however, the efficacy of any cell therapy relies on the successful delivery of intact and functioning cells. Here, the effect of delivering pericytes on wound repair was assessed alongside the development of a surface-functionalized pericyte patch. Plasma polymerization (PP) was used to functionalize the surface of silicone patches with heptylamine (HA) or acrylic acid (AA) monomers. Human pericytes were subsequently delivered to murine excisional wounds by intradermal injection or using the pericyte-laden patches and the comparative effects on wound healing, inflammation and revascularization determined. The AA surface provided the superior transfer of the cells to de-epidermized dermis. Excisional murine wounds treated either with pericytes injected directly into the wound or with the pericyte-laden AA patches showed improved healing with decreased neutrophil infiltration and reduced numbers of macrophages in the wounds. Pericyte delivery also enhanced angiogenesis through a mechanism independent of VEGF signalling. Pericytes, when delivered to wounds, improved healing responses by dampening inflammation and promoting angiogenesis. Delivery of pericytes using PP-AA-functionalized patches was equally as effective as direct injection of pericytes into wounds. Pericyte-functionalized dressings may therefore be a clinically relevant approach for the treatment of wounds.

Optimization of oxidative stress for mesenchymal stromal/stem cell engraftment, function and longevity

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that possess great potential as a cellular therapeutic based on their ability to differentiate to different lineages and to modulate immune responses. However, their potential is limited by their low tissue abundance, and thus the need for robust ex vivo expansion prior to their application. This creates its own issues, namely replicative senescence, which could lead to reduced MSC functionality and negatively impact their engraftment. Ex vivo expansion and MSC aging are associated with greater oxidative stress. Therefore, there is great need to identify strategies to reduce oxidative stress in MSCs. This review summarizes the achievements made to date in addressing oxidative stress in MSCs and speculates about interesting avenues of future investigation to solve this critical problem.

Cell spheroids are as effective as single cells suspensions in the treatment of critical-sized bone defects

Background

Due to their multilineage potential and high proliferation rate, mesenchymal stem cells (MSC) indicate a sufficient alternative in regenerative medicine. In comparison to the commonly used 2-dimensional culturing method, culturing cells as spheroids stimulates the cell-cell communication and mimics the in vivo milieu more accurately, resulting in an enhanced regenerative potential. To investigate the osteoregenerative potential of MSC spheroids in comparison to MSC suspensions, cell-loaded fibrin gels were implanted into murine critical-sized femoral bone defects.

Methods

After harvesting MSCs from 4 healthy human donors and preculturing and immobilizing them in fibrin gel, cells were implanted into 2 mm murine femoral defects and stabilized with an external fixator. Therefore, 26 14- to 15-week-old nu/nu NOD/SCID nude mice were randomized into 2 groups (MSC spheroids, MSC suspensions) and observed for 6 weeks. Subsequently, micro-computed tomography scans were performed to analyze regenerated bone volume and bone mineral density. Additionally, histological analysis, evaluating the number of osteoblasts, osteoclasts and vessels at the defect side, were performed.

Statistical analyzation was performed by using the Student’s t-test and, the Mann-Whitney test. The level of significance was set at p = 0.05.

Results

μCT-analysis revealed a significantly higher bone mineral density of the MSC spheroid group compared to the MSC suspension group. However, regenerated bone volume of the defect side was comparable between both groups. Furthermore, no significant differences in histological analysis between both groups could be shown.

Conclusion

Our in vivo results reveal that the osteo-regenerative potential of MSC spheroids is similar to MSC suspensions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04264-y.

Cardiac Tissues From Stem Cells: New Routes to Maturation and Cardiac Regeneration

The ability of human pluripotent stem cells to form all cells of the body has provided many opportunities to study disease and produce cells that can be used for therapy in regenerative medicine. Even though beating cardiomyocytes were among the first cell types to be differentiated from human pluripotent stem cell, cardiac applications have advanced more slowly than those, for example, for the brain, eye, and pancreas. This is, in part, because simple 2-dimensional human pluripotent stem cell cardiomyocyte cultures appear to need crucial functional cues normally present in the 3-dimensional heart structure. Recent tissue engineering approaches combined with new insights into the dialogue between noncardiomyocytes and cardiomyocytes have addressed and provided solutions to issues such as cardiomyocyte immaturity and inability to recapitulate adult heart values for features like contraction force, electrophysiology, or metabolism. Three-dimensional bioengineered heart tissues are thus poised to contribute significantly to disease modeling, drug discovery, and safety pharmacology, as well as provide new modalities for heart repair. Here, we review the current status of 3-dimensional engineered heart tissues.

Adult Stem Cell Therapy for Premature Ovarian Failure: From Bench to Bedside

Premature ovarian failure (POF) is a devastating condition for women of childbearing age with serious health consequences, including distress, infertility, osteoporosis, autoimmune disorders, ischemic heart disease, and increased mortality. In addition to the mainstay estrogen therapy, stem cell therapy has been tested as the result of rapid progress in cell biology and reprogramming research. We hereby provide a review for the latest research and issues related with stem cell-based therapy for POF, and provide a commentary on various methods for enhancing its effect. Large amount of animal studies have demonstrated an extensive benefit of stem cells for failed ovarian recovering. As shown by such studies, stem cell therapy can result in recovery of hormonal levels, follicular activation, ovarian angiogenesis, and functional restoration. Meanwhile, a study of molecular pathways revealed that the function of stem cells mainly depends on their paracrine actions, which can produce multiple factors for the promotion of ovarian angiogenesis and regulation of cellular functions. Nevertheless, studies using disease models also revealed certain drawbacks. Clinical trials have shown that menstrual cycle and even pregnancy may occur in POF patients following transplantation of stem cells, although the limitations, including inadequate number of cases and space for the improvement of transplantation methodology. Only with its safety and effect get substantial improvement through laboratory experiments and clinical trials, can stem cell therapy really bring benefits to more patients. Additionally, effective pretreatment and appropriate transplantation methods for stem cells are also required. Taken together, stem cell therapy has shown a great potential for the reversal of POF and is stepping from bench to bedside. Impact statement Premature ovarian failure (POF) is a devastating condition with serious clinical consequences. The purpose of this review was to summarize the current status of stem cell therapy for POF. Considering the diversity of cell types and functions, a rigorous review is required for the guidance for further research into this field. Meanwhile, the challenges and prospect for clinical application of stem cell treatment, methodological improvements, and innovations are addressed.

Sustained subcutaneous delivery of secretome of human cardiac stem cells promotes cardiac repair following myocardial infarction

AIMS

To establish pre-clinical proof of concept that sustained subcutaneous delivery of the secretome of human cardiac stem cells (CSCs) can be achieved in vivo to produce significant cardioreparative outcomes in the setting of myocardial infarction.

METHODS AND RESULTS

Rats were subjected to permanent ligation of left anterior descending coronary artery and randomized to receive subcutaneous implantation of TheraCyte devices containing either culture media as control or 1 × 106 human W8B2+ CSCs, immediately following myocardial ischaemia. At 4 weeks following myocardial infarction, rats treated with W8B2+ CSCs encapsulated within the TheraCyte device showed preserved left ventricular ejection fraction. The preservation of cardiac function was accompanied by reduced fibrotic scar tissue, interstitial fibrosis, cardiomyocyte hypertrophy, as well as increased myocardial vascular density. Histological analysis of the TheraCyte devices harvested at 4 weeks post-implantation demonstrated survival of human W8B2+ CSCs within the devices, and the outer membrane was highly vascularized by host blood vessels. Using CSCs expressing plasma membrane reporters, extracellular vesicles of W8B2+ CSCs were found to be transferred to the heart and other organs at 4 weeks post-implantation. Furthermore, mass spectrometry-based proteomic profiling of extracellular vesicles of W8B2+ CSCs identified proteins implicated in inflammation, immunoregulation, cell survival, angiogenesis, as well as tissue remodelling and fibrosis that could mediate the cardioreparative effects of secretome of human W8B2+ CSCs.

CONCLUSIONS

Subcutaneous implantation of TheraCyte devices encapsulating human W8B2+ CSCs attenuated adverse cardiac remodelling and preserved cardiac function following myocardial infarction. The TheraCyte device can be employed to deliver stem cells in a minimally invasive manner for effective secretome-based cardiac therapy.

Application of Cell, Tissue, and Biomaterial Delivery in Cardiac Regenerative Therapy

Cardiovascular diseases (CVD) are the leading cause of death around the world, being responsible for 31.8% of all deaths in 2017 (Roth, G. A. et al. The Lancet 2018, 392, 1736-1788). The leading cause of CVD is ischemic heart disease (IHD), which caused 8.1 million deaths in 2013 (Benjamin, E. J. et al. Circulation 2017, 135, e146-e603). IHD occurs when coronary arteries in the heart are narrowed or blocked, preventing the flow of oxygen and blood into the cardiac muscle, which could provoke acute myocardial infarction (AMI) and ultimately lead to heart failure and death. Cardiac regenerative therapy aims to repair and refunctionalize damaged heart tissue through the application of (1) intramyocardial cell delivery, (2) epicardial cardiac patch, and (3) acellular biomaterials. In this review, we aim to examine these current approaches and challenges in the cardiac regenerative therapy field.