Multipotent mesenchymal stromal cell therapy and risk of malignancies. Stem Cell Rev Rep. 2013;9:65-79. [PMID: 22237468 DOI: 10.1007/s12015-011-9345-4]

Current status of stem cell therapy for type 1 diabetes: a critique and a prospective consideration

Over the past decade, there had been progress in the development of cell therapy for insulin-dependent diabetes. Nevertheless, important hurdles that need to be overcome still remain. Protocols for the differentiation of pluripotent stem cells into pancreatic progenitors or fully differentiated β-cells have been developed. The resulting insulin-producing cells can control chemically induced diabetes in rodents and were the subject of several clinical trials. However, these cells are immunogenic and possibly teratogenic for their transplantation, and an immunoisolation device and/or immunosuppression is needed. A growing number of studies have utilized genetic manipulations to produce immune evasive cells. Evidence must be provided that in addition to the expected benefit, gene manipulations should not lead to any unforeseen complications. Mesenchymal stem/stromal cells (MSCs) can provide a viable alternative. MSCs are widely available from many tissues. They can form insulin-producing cells by directed differentiation. Experimentally, evidence has shown that the transplantation of allogenic insulin-producing cells derived from MSCs is associated with a muted allogeneic response that does not interfere with their functionality. This can be explained by the immunomodulatory functions of the MSC subpopulation that did not differentiate into insulin-producing cells. Recently, exosomes derived from naive MSCs have been used in the experimental domain to treat diabetes in rodents with varying degrees of success. Several mechanisms for their beneficial functions were proposed including a reduction in insulin resistance, the promotion of autophagy, and an increase in the T regulatory population. However, euglycemia was not achieved in any of these experiments. We suggest that exosomes derived from β-cells or insulin-producing cells (educated) can provide a better therapeutic effect than those derived from undifferentiated cells.

Autologous mesenchymal stem cell therapy for diabetic men with erectile dysfunction. Is it promising? A pilot study

PURPOSE

to assess safety and efficacy of autologous mesenchymal bone marrow stem cell injection in penile cavernosal tissue for erectile dysfunction therapy in diabetic men.

METHODS

The subjects of this study were diabetic men suffering erectile dysfunction, non-responding to maximum dose of oral PDE5I. Mesenchymal bone marrow stem cells were aspirated and injected after preparation in both corpora cavernosa at 3, 9 o'clock position. Erectile function was assessed by the International Index of Erectile Function and penile Doppler study, before and after 6 months after injection.

RESULTS

4 patients out of 10 achieve hard erection adequate for satisfactory coitus, and 2 patients achieved penile hardness with addition of pharmacological therapy with sildenafil 100mg. Peak systolic velocity increased significantly in 4 patients (2 arteriogenic and 2 mixed erectile dysfunction), from 12∼22 cm/s to 32∼69 cm/s. Variations in end-diastolic velocity increased substantially in 2 patients with venogenic insufficiency alone at follow-up from 4∼5 cm /s to -4∼-3 cm/s.

CONCLUSIONS

Despite promising stem cell treatment efficacy for patients with erectile dysfunction, more clinical studies and researches are still warranted.

Progress in research on mesenchymal stem cells and their extracellular vesicles for treating fibrosis in systemic sclerosis

Systemic sclerosis (SSc) refers to an autoimmune disease characterized by immune dysfunction, vascular endothelial damage, and multi-organ fibrosis. Thus far, this disease is incurable, and its high mortality rate is significantly correlated with fibrotic events. Fibrosis has been confirmed as a difficult clinical treatment area that should be urgently treated in clinical medicine. Mesenchymal stem cells (MSCs) exhibit immunomodulatory, pro-angiogenic, and anti-fibrotic functions. MSCs-derived extracellular vesicles (EVs) have aroused rising interest as a cellular component that retains the functions of MSCs while circumventing the possible adverse effects of MSCs. Moreover, EVs have great potential in treating SSc. In this study, the current research progress on MSCs and their EVs for treating fibrosis in SSc was reviewed, with an aim to provide some reference for future MSCs and their EVs in treating SSc.

Apoptotic Vesicles of MSCs: The Natural Therapeutic Agents and Bio-Vehicles for Targeting Drug Delivery

Mesenchymal stem cell (MSC)-based therapies are increasingly recognized as promising cellular therapeutics and show the ability to treat various diseases. However, the underlying mechanism is not fully elucidated. Some recent studies have shown an unexpected result whereby MSCs undergo rapid apoptosis following administration but still exert therapeutic effects in some disease treatments. Such a therapeutic mechanism is believed to associate with the released apoptotic vesicles from apoptotic MSCs (MSC-ApoVs). This finding inspires a novel therapeutic strategy for using MSC-ApoVs for disease treatment. The present review aims to summarize the biogenesis, physiological functions, therapeutic potentials, and related mechanisms of apoptotic vesicles in MSC-based therapy. In addition, the potential applications of MSC-ApoVs as natural therapeutic agents and natural drug delivery vehicles are proposed and highlighted. The present review is hoped to provide a general understanding of MSC-ApoVs in disease treatment and inspire potential applications in targeted drug delivery.

Transition metals in angiogenesis - A narrative review

The aim of this paper is to offer a narrative review of the literature regarding the influence of transition metals on angiogenesis, excluding lanthanides and actinides. To our knowledge there are not any reviews up to date offering such a summary, which inclined us to write this paper. Angiogenesis describes the process of blood vessel formation, which is an essential requirement for human growth and development. When the complex interplay between pro- and antiangiogenic mediators falls out of balance, angiogenesis can quickly become harmful. As it is so fundamental, both its inhibition and enhancement take part in various diseases, making it a target for therapeutic treatments. Current methods come with limitations, therefore, novel agents are constantly being researched, with metal agents offering promising results. Various transition metals have already been investigated in-depth, with studies indicating both pro- and antiangiogenic properties, respectively. The transition metals are being applied in various formulations, such as nanoparticles, complexes, or scaffold materials. Albeit the increasing attention this field is receiving, there remain many unanswered questions, mostly regarding the molecular mechanisms behind the observed effects. Notably, approximately half of all the transition metals have not yet been investigated regarding potential angiogenic effects. Considering the promising results which have already been established, it should be of great interest to begin investigating the remaining elements whilst also further analyzing the established effects.

Safety and Preliminary Efficacy of Mesenchymal Stromal Cell (ORBCEL-M) Therapy in Diabetic Kidney Disease: A Randomized Clinical Trial (NEPHSTROM)

SIGNIFICANCE STATEMENT

Mesenchymal stromal cells (MSCs) may offer a novel therapy for diabetic kidney disease (DKD), although clinical translation of this approach has been limited. The authors present findings from the first, lowest dose cohort of 16 adults with type 2 diabetes and progressive DKD participating in a randomized, placebo-controlled, dose-escalation phase 1b/2a trial of next-generation bone marrow-derived, anti-CD362 antibody-selected allogeneic MSCs (ORBCEL-M). A single intravenous (iv) infusion of 80×10 6 cells was safe and well-tolerated, with one quickly resolved infusion reaction in the placebo group and no subsequent treatment-related serious adverse events (SAEs). Compared with placebo, the median annual rate of decline in eGFR was significantly lower with ORBCEL-M, although mGFR did not differ. The results support further investigation of ORBCEL-M in this patient population in an appropriately sized phase 2b study.

BACKGROUND

Systemic therapy with mesenchymal stromal cells may target maladaptive processes involved in diabetic kidney disease progression. However, clinical translation of this approach has been limited.

METHODS

The Novel Stromal Cell Therapy for Diabetic Kidney Disease (NEPHSTROM) study, a randomized, placebo-controlled phase 1b/2a trial, assesses safety, tolerability, and preliminary efficacy of next-generation bone marrow-derived, anti-CD362-selected, allogeneic mesenchymal stromal cells (ORBCEL-M) in adults with type 2 diabetes and progressive diabetic kidney disease. This first, lowest dose cohort of 16 participants at three European sites was randomized (3:1) to receive intravenous infusion of ORBCEL-M (80×10 6 cells, n =12) or placebo ( n =4) and was followed for 18 months.

RESULTS

At baseline, all participants were negative for anti-HLA antibodies and the measured GFR (mGFR) and estimated GFR were comparable between groups. The intervention was safe and well-tolerated. One placebo-treated participant had a quickly resolved infusion reaction (bronchospasm), with no subsequent treatment-related serious adverse events. Two ORBCEL-M recipients died during follow-up of causes deemed unrelated to the trial intervention; one recipient developed low-level anti-HLA antibodies. The median annual rate of kidney function decline after ORBCEL-M therapy compared with placebo did not differ by mGFR, but was significantly lower by eGFR estimated by the Chronic Kidney Disease Epidemiology Collaboration and Modification of Diet in Renal Disease equations. Immunologic profiling provided evidence of preservation of circulating regulatory T cells, lower natural killer T cells, and stabilization of inflammatory monocyte subsets in those receiving the cell therapy compared with placebo.

CONCLUSIONS

Findings indicate safety and tolerability of intravenous ORBCEL-M cell therapy in the trial's lowest dose cohort. The rate of decline in eGFR (but not mGFR) over 18 months was significantly lower among those receiving cell therapy compared with placebo. Further studies will be needed to determine the therapy's effect on CKD progression.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrial.gov NCT02585622 .

A phase I study of autologous mesenchymal stromal cells for severe steroid-dependent nephrotic syndrome

BACKGROUNDSevere forms of idiopathic nephrotic syndrome (INS) require prolonged immunosuppressive therapies and repeated courses of high-dose glucocorticoids. Mesenchymal stromal cells (MSCs) have promising immunomodulatory properties that may be employed therapeutically to reduce patient exposure to medications and their side effects.METHODSWe performed a phase I open-label trial assessing safety and feasibility of autologous bone marrow-derived MSCs (BM-MSCs) in children and young adults with severe forms of steroid-dependent nephrotic syndrome. Following autologous BM-MSC preparation and infusion, oral immunosuppression was tapered. Safety, efficacy, and immunomodulatory effects in vivo were monitored for 12 months.RESULTSSixteen patients (10 children, 6 adults) were treated. Adverse events were limited and not related to BM-MSC infusions. All patients relapsed during follow-up, but in the 10 treated children, time to first relapse was delayed (P = 0.02) and number of relapses was reduced (P = 0.002) after BM-MSC infusion, compared with the previous 12 months. Cumulative prednisone dose was also reduced at 12 months compared with baseline (P < 0.05). No treatment benefit was observed in adults.In children, despite tapering of immunosuppression, clinical benefit was mirrored by a significant reduction in total CD19+, mature, and memory B cells and an increase in regulatory T cells in vivo up to 3-6 months following BM-MSC infusionCONCLUSIONTreatment with autologous BM-MSCs is feasible and safely reduces relapses and immunosuppression at 12 months in children with severe steroid-dependent INS. Immunomodulatory studies suggest that repeating MSC infusions at 3-6 months may sustain benefit.TRIAL REGISTRATIONEudraCT 2016-004804-77.FUNDINGAIFA Ricerca Indipendente 2016-02364623.

Engineered Nano-Bio Interfaces for Stem Cell Therapy

Engineered nanomaterials (ENMs) with different topographies provide effective nano-bio interfaces for controlling the differentiation of stem cells. The interaction of stem cells with nanoscale topographies and chemical cues in their microenvironment at the nano-bio interface can guide their fate. The use of nanotopographical cues, in particular nanorods, nanopillars, nanogrooves, nanofibers, and nanopits, as well as biochemical forces mediated factors, including growth factors, cytokines, and extracellular matrix proteins, can significantly impact stem cell differentiation. These factors were seen as very effective in determining the proliferation and spreading of stem cells. The specific outgrowth of stem cells can be decided with size variation of topographic nanomaterial along with variation in matrix stiffness and surface structure like a special arrangement. The precision chemistry enabled controlled design, synthesis, and chemical composition of ENMs can regulate stem cell behaviors. The parameters of size such as aspect ratio, diameter, and pore size of nanotopographic structures are the main factors for specific termination of stem cells. Protein corona nanoparticles (NPs) have shown a powerful facet in stem cell therapy, where combining specific proteins could facilitate a certain stem cell differentiation and cellular proliferation. Nano-bio reactions implicate the interaction between biological entities and nanoparticles, which can be used to tailor the stem cells' culmination. The ion release can also be a parameter to enhance cellular proliferation and to commit the early differentiation of stem cells. Further research is needed to fully understand the mechanisms underlying the interactions between engineered nano-bio interfaces and stem cells and to develop optimized regenerative medicine and tissue engineering designs.

Liver Disease and Cell Therapy: Advances Made and Remaining Challenges

The limited availability of organs for liver transplantation, the ultimate curative treatment for end stage liver disease, has resulted in a growing and unmet need for alternative therapies. Mesenchymal stromal cells (MSCs) with their broad ranging anti-inflammatory and immunomodulatory properties have therefore emerged as a promising therapeutic agent in treating inflammatory liver disease. Significant strides have been made in exploring their biological activity. Clinical application of MSC has shifted the paradigm from using their regenerative potential to one which harnesses their immunomodulatory properties. Reassuringly, MSCs have been extensively investigated for over 30 years with encouraging efficacy and safety data from translational and early phase clinical studies, but questions remain about their utility. Therefore, in this review, we examine the translational and clinical studies using MSCs in various liver diseases and their impact on dampening immune-mediated liver damage. Our key observations include progress made thus far with use of MSCs for clinical use, inconsistency in the literature to allow meaningful comparison between different studies and need for standardized protocols for MSC manufacture and administration. In addition, the emerging role of MSC-derived extracellular vesicles as an alternative to MSC has been reviewed. We have also highlighted some of the remaining clinical challenges that should be addressed before MSC can progress to be considered as therapy for patients with liver disease.

Current and Novel Therapeutics for Articular Cartilage Repair and Regeneration

Articular cartilage repair is a sophisticated process that has is being recently investigated. There are several different approaches that are currently reported to promote cartilage repair, like cell-based therapies, biologics, and physical therapy. Cell-based therapies involve the using stem cells or chondrocytes, which make up cartilage, to promote the growth of new cartilage. Biologics, like growth factors, are also being applied to enhance cartilage repair. Physical therapy, like exercise and weight-bearing activities, can also be used to promote cartilage repair by inducing new cartilage growth and improving joint function. Additionally, surgical options like osteochondral autograft, autologous chondrocyte implantation, microfracture, and others are also reported for cartilage regeneration. In the current literature review, we aim to provide an up-to-date discussion about these approaches and discuss the current research status.

Stem Cell Therapy for Acute/Subacute Ischemic Stroke with a Focus on Intraarterial Stem Cell Transplantation: From Basic Research to Clinical Trials

Stem cell therapy for ischemic stroke holds great promise for the treatment of neurological impairment and has moved from the laboratory into early clinical trials. The mechanism of action of stem cell therapy includes the bystander effect and cell replacement. The bystander effect plays an important role in the acute to subacute phase, and cell replacement plays an important role in the subacute to chronic phase. Intraarterial (IA) transplantation is less invasive than intraparenchymal transplantation and can provide more cells in the affected brain region than intravenous transplantation. However, transplanted cell migration was reported to be insufficient, and few transplanted cells were retained in the brain for an extended period. Therefore, the bystander effect was considered the main mechanism of action of IA stem cell transplantation. In most clinical trials, IA transplantation was performed during the acute and subacute phases. Although clinical trials of IA transplantation demonstrated safety, they did not demonstrate satisfactory efficacy in improving patient outcomes. To increase efficacy, increased migration of transplanted cells and production of long surviving and effective stem cells would be crucial. Given the lack of knowledge on this subject, we review and summarize the mechanisms of action of transplanted stem cells and recent advancements in preclinical and clinical studies to provide information and guidance for further advancement of acute/subacute phase IA stem cell transplantation therapy for ischemic stroke.

The Therapeutic Potential of Mesenchymal Stem Cells in the Treatment of Diabetes Mellitus

Mesenchymal stem cells (MSCs) exist in many tissues and can differentiate into cells of multiple lineages, such as adipocytes, osteoblasts, or chondrocytes. MSC administration has demonstrated therapeutic potential in various degenerative and inflammatory diseases (e.g., graft-vs.-host disease, multiple sclerosis, Crohn's disease, organ fibrosis, and diabetes mellitus [DM]). The mechanisms involved in the therapeutic effects of MSCs are multifaceted. Generally, implanted MSCs can migrate to sites of injury, where they establish an anti-inflammatory and regenerative microenvironment in damaged tissues. In addition, MSCs can modulate innate and adaptive immune responses through immunosuppressive mechanisms that involve immune cells, inflammatory cytokines, chemokines, and immunomodulatory factors. DM has a high prevalence worldwide; it also contributes to a high rate of mortality worldwide. MSCs offer a promising therapeutic agent to prevent or repair damage from DM and diabetic complications through properties such as multilineage differentiation, homing, promotion of angiogenesis, and immunomodulation (e.g., prevention of oxidative stress, fibrosis, and cell death). In this study, we review current findings regarding the immunomodulatory and regenerative mechanisms of MSCs, as well as their therapeutic applications in DM and DM-related complications.

Mesenchymal Stem Cell-Derived Exosome Therapy of Microbial Diseases: From Bench to Bed

Microbial diseases are a global health threat, leading to tremendous casualties and economic losses. The strategy to treat microbial diseases falls into two broad categories: pathogen-directed therapy (PDT) and host-directed therapy (HDT). As the typical PDT, antibiotics or antiviral drugs directly attack bacteria or viruses through discerning specific molecules. However, drug abuse could result in antimicrobial resistance and increase infectious disease morbidity. Recently, the exosome therapy, as a HDT, has attracted extensive attentions for its potential in limiting infectious complications and targeted drug delivery. Mesenchymal stem cell-derived exosomes (MSC-Exos) are the most broadly investigated. In this review, we mainly focus on the development and recent advances of the application of MSC-Exos on microbial diseases. The review starts with the difficulties and current strategies in antimicrobial treatments, followed by a comprehensive overview of exosomes in aspect of isolation, identification, contents, and applications. Then, the underlying mechanisms of the MSC-Exo therapy in microbial diseases are discussed in depth, mainly including immunomodulation, repression of excessive inflammation, and promotion of tissue regeneration. In addition, we highlight the latest progress in the clinical translation of the MSC-Exo therapy, by summarizing related clinical trials, routes of administration, and exosome modifications. This review will provide fundamental insights and future perspectives on MSC-Exo therapy in microbial diseases from bench to bedside.

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.

OUP accepted manuscript

Background

Left ventricular hypertrophy and heart failure with preserved ejection fraction (HFpEF) are primary manifestations of the cardiorenal syndrome in patients with chronic kidney disease (CKD). Therapies that improve morbidity and mortality in HFpEF are lacking. Cell-based therapies promote cardiac repair in ischemic and non-ischemic cardiomyopathies. We hypothesized that cell-based therapy ameliorates CKD-induced HFpEF.

Methods and Results

Yorkshire pigs (n = 26) underwent 5/6 embolization-mediated nephrectomy. CKD was confirmed by increased creatinine and decreased glomerular filtration rate (GFR). Mean arterial pressure (MAP) was not different between groups from baseline to 4 weeks. HFpEF was evident at 4 weeks by increased LV mass, relative wall thickening, end-diastolic pressure, and end-diastolic pressure-volume relationship, with no change in ejection fraction (EF). Four weeks post-embolization, allogeneic (allo) bone marrow-derived mesenchymal stem cells (MSC; 1 × 10⁷ cells), allo-kidney-derived stem cells (KSC; 1 × 10⁷ cells), allo-cell combination therapy (ACCT; MSC + KSC; 1:1 ratio; total = 1 × 10⁷ cells), or placebo (Plasma-Lyte) was delivered via intra-renal artery. Eight weeks post-treatment, there was a significant increase in MAP in the placebo group (21.89 ± 6.05 mmHg) compared to the ACCT group. GFR significantly improved in the ACCT group. EF, relative wall thickness, and LV mass did not differ between groups at 12 weeks. EDPVR improved in the ACCT group, indicating decreased ventricular stiffness.

Conclusions

Intra-renal artery allogeneic cell therapy was safe in a CKD swine model manifesting the characteristics of HFpEF. The beneficial effect on renal function and ventricular compliance in the ACCT group supports further research of cell therapy for cardiorenal syndrome.

Klotho and Mesenchymal Stem Cells: A Review on Cell and Gene Therapy for Chronic Kidney Disease and Acute Kidney Disease

Chronic kidney disease (CKD) and acute kidney injury (AKI) are public health problems, and their prevalence rates have increased with the aging of the population. They are associated with the presence of comorbidities, in particular diabetes mellitus and hypertension, resulting in a high financial burden for the health system. Studies have indicated Klotho as a promising therapeutic approach for these conditions. Klotho reduces inflammation, oxidative stress and fibrosis and counter-regulates the renin-angiotensin-aldosterone system. In CKD and AKI, Klotho expression is downregulated from early stages and correlates with disease progression. Therefore, the restoration of its levels, through exogenous or endogenous pathways, has renoprotective effects. An important strategy for administering Klotho is through mesenchymal stem cells (MSCs). In summary, this review comprises in vitro and in vivo studies on the therapeutic potential of Klotho for the treatment of CKD and AKI through the administration of MSCs.

Progress and prospect of stem cell therapy for diabetic erectile dysfunction

Diabetic erectile dysfunction (DED) is a common complication of diabetes mellitus, significantly impairing the quality of life of patients. The conventional clinical treatment still has limitations. Stem cells (SCs), as a type of cells with multidirectional or directional differentiation capability and sustainable self-renewal potential, are widely used in regenerative medicine and tissue engineering. With the continuous update of regenerative medicine theory and the success of animal experiments, SCs as a treatment for male erectile dysfunction, especially DED, have attracted widespread attention because of curable possibility. This review focus on the current progress in the clinical application of SC treatment for DED. Moreover, we summarize the development prospects of SCs in the field of DMED therapy.

Mesenchymal stem cell therapy in decompensated liver cirrhosis: a long-term follow-up analysis of the randomized controlled clinical trial

BACKGROUND

Mesenchymal stem cell (MSC) infusion was reported to improve liver function in patients with decompensated liver cirrhosis (DLC); however, whether the medication can improve outcome of these patients is poorly understood.

METHODS

This prospective, open-labeled, randomized controlled study enrolled 219 patients with HBV-related DLC who were divided into control group (n = 111) and umbilical cord-derived MSC (UC-MSC)-treated group (n = 108), then all of them received a follow-up check from October 2010 to October 2017. The treated patients received three times of UC-MSC infusions at 4-week intervals plus conventional treatment that was only used for control group. The overall survival rate and HCC-free survival rate were calculated as primary endpoints and the liver function and adverse events associated with the medication were also evaluated.

RESULTS

During the follow-up check period from 13 to 75th months, there was a significantly higher overall survival rate in the treated group than the control group, while the difference of the hepatocellular carcinoma event-free survival rate between the treated and control groups was not observed during the 75-month follow-up. UC-MSC treatment markedly improved liver function, as indicated by the levels of serum albumin, prothrombin activity, cholinesterase, and total bilirubin during 48 weeks of follow-up. No significant side effects or treatment-related complications were observed in the UC-MSC group.

CONCLUSIONS

Therapy of UC-MSC is not only well tolerated, but also significantly improves long-term survival rate, as well as the liver function in patients with HBV-related DLC. UC-MSC medication, therefore, might present a novel therapeutic approach for the disease.

Myeloid and Mesenchymal Stem Cell Therapies for Solid Organ Transplant Tolerance

Transplantation is now performed globally as a routine procedure. However, the increased demand for donor organs and consequent expansion of donor criteria has created an imperative to maximize the quality of these gains. The goal is to balance preservation of allograft function against patient quality-of-life, despite exposure to long-term immunosuppression. Elimination of immunosuppressive therapy to avoid drug toxicity, with concurrent acceptance of the allograft-so-called operational tolerance-has proven elusive. The lack of recent advances in immunomodulatory drug development, together with advances in immunotherapy in oncology, has prompted interest in cell-based therapies to control the alloimmune response. Extensive experimental work in animals has characterized regulatory immune cell populations that can induce and maintain tolerance, demonstrating that their adoptive transfer can promote donor-specific tolerance. An extension of this large body of work has resulted in protocols for manufacture, as well as early-phase safety and feasibility trials for many regulatory cell types. Despite the excitement generated by early clinical trials in autoimmune diseases and organ transplantation, there is as yet no clinically validated, approved regulatory cell therapy for transplantation. In this review, we summarize recent advances in this field, with a focus on myeloid and mesenchymal cell therapies, including current understanding of the mechanisms of action of regulatory immune cells, and clinical trials in organ transplantation using these cells as therapeutics.

Anti-senescence ion-delivering nanocarrier for recovering therapeutic properties of long-term-cultured human adipose-derived stem cells

BACKGROUND

Human adipose-derived stem cells (hADSCs) have been used in various fields of tissue engineering because of their promising therapeutic efficacy. However, the stemness of hADSCs cannot be maintained for long durations, and their therapeutic cellular functions, such as paracrine factor secretion decrease during long-term cell culture. To facilitate the use of long-term-cultured hADSCs (L-ADSCs), we designed a novel therapeutic anti-senescence ion-delivering nanocarrier (AIN) that is capable of recovering the therapeutic properties of L-ADSCs. In the present study, we introduced a low-pH-responsive ion nanocarrier capable of delivering transition metal ions that can enhance angiogenic paracrine factor secretion from L-ADSCs. The AINs were delivered to L-ADSCs in an intracellular manner through endocytosis.

RESULTS

Low pH conditions within the endosomes induced the release of transition metal ions (Fe) into the L-ADSCs that in turn caused a mild elevation in the levels of reactive oxygen species (ROS). This mild elevation in ROS levels induced a downregulation of senescence-related gene expression and an upregulation of stemness-related gene expression. The angiogenic paracrine factor secretion from L-ADSCs was significantly enhanced, and this was evidenced by the observed therapeutic efficacy in response to treatment of a wound-closing mouse model with conditioned medium obtained from AIN-treated L-ADSCs that was similar to that observed in response to treatment with short-term-cultured adipose-derived stem cells.

CONCLUSIONS

This study suggests a novel method and strategy for cell-based tissue regeneration that can overcome the limitations of the low stemness and therapeutic efficacy of stem cells that occurs during long-term cell culture.

Mesenchymal Stromal Cells: an Antimicrobial and Host-Directed Therapy for Complex Infectious Diseases

There is an urgent need for new antimicrobial strategies for treating complex infections and emerging pathogens. Human mesenchymal stromal cells (MSCs) are adult multipotent cells with antimicrobial properties, mediated through direct bactericidal activity and modulation of host innate and adaptive immune cells. More than 30 in vivo studies have reported on the use of human MSCs for the treatment of infectious diseases, with many more studies of animal MSCs in same-species models of infection. MSCs demonstrate potent antimicrobial effects against the major classes of human pathogens (bacteria, viruses, fungi, and parasites) across a wide range of infection models. Mechanistic studies have yielded important insight into their immunomodulatory and bactericidal activity, which can be enhanced through various forms of preconditioning. MSCs are being investigated in over 80 clinical trials for difficult-to-treat infectious diseases, including sepsis and pulmonary, intra-abdominal, cutaneous, and viral infections. Completed trials consistently report MSCs to be safe and well tolerated, with signals of efficacy against some infectious diseases. Although significant obstacles must be overcome to produce a standardized, affordable, clinical-grade cell therapy, these studies suggest that MSCs may have particular potential as an adjunct therapy in complex or resistant infections.

Human Amniotic Epithelial Stem Cell-Derived Retinal Pigment Epithelium Cells Repair Retinal Degeneration

Age-related macular degeneration (AMD), featured with dysfunction and loss of retinal pigment epithelium (RPE), is lacking efficient therapeutic approaches. According to our previous studies, human amniotic epithelial stem cells (hAESCs) may serve as a potential seed cell source of RPE cells for therapy because they have no ethical concerns, no tumorigenicity, and little immunogenicity. Herein, trichostatin A and nicotinamide can direct hAESCs differentiation into RPE like cells. The differentiated cells display the morphology, marker expression and cellular function of the native RPE cells, and noticeably express little MHC class II antigens and high level of HLA-G. Moreover, visual function and retinal structure of Royal College of Surgeon (RCS) rats, a classical animal model of retinal degeneration, were rescued after subretinal transplantation with the hAESCs-derived RPE like cells. Our study possibly makes some contribution to the resource of functional RPE cells for cell therapy. Subretinal transplantation of hAESCs-RPE could be an optional therapeutic strategy for retinal degeneration diseases.

Therapeutic Implications of Mesenchymal Stromal Cells and Their Extracellular Vesicles in Autoimmune Diseases: From Biology to Clinical Applications

Mesenchymal stromal cells (MSCs) are perivascular multipotent stem cells originally identified in the bone marrow (BM) stroma and subsequently in virtually all vascularized tissues. Because of their ability to differentiate into various mesodermal lineages, their trophic properties, homing capacity, and immunomodulatory functions, MSCs have emerged as attractive candidates in tissue repair and treatment of autoimmune disorders. Accumulating evidence suggests that the beneficial effects of MSCs may be primarily mediated via a number of paracrine-acting soluble factors and extracellular vesicles (EVs). EVs are membrane-coated vesicles that are increasingly being acknowledged as playing a key role in intercellular communication via their capacity to carry and deliver their cargo, consisting of proteins, nucleic acids, and lipids to recipient cells. MSC-EVs recapitulate the functions of the cells they originate, including immunoregulatory effects but do not seem to be associated with the limitations and concerns of cell-based therapies, thereby emerging as an appealing alternative therapeutic option in immune-mediated disorders. In the present review, the biology of MSCs will be outlined and an overview of their immunomodulatory functions will be provided. In addition, current knowledge on the features of MSC-EVs and their immunoregulatory potential will be summarized. Finally, therapeutic applications of MSCs and MSC-EVs in autoimmune disorders will be discussed.

Third-party bone marrow-derived mesenchymal stromal cell infusion before liver transplantation: A randomized controlled trial

Mesenchymal stromal cells (MSC) have emerged as a promising therapy to minimize the immunosuppressive regimen or induce tolerance in solid organ transplantation. In this randomized open-label phase Ib/IIa clinical trial, 20 liver transplant patients were randomly allocated (1:1) to receive a single pretransplant intravenous infusion of third-party bone marrow-derived MSC or standard of care alone. The primary endpoint was the safety profile of MSC administration during the 1-year follow-up. In all, 19 patients completed the study, and none of those who received MSC experienced infusion-related complications. The incidence of serious and non-serious adverse events was similar in the two groups. Circulating Treg/memory Treg and tolerant NK subset of CD56^bright NK cells increased slightly over baseline, albeit not to a statistically significant extent, in MSC-treated patients but not in the control group. Graft function and survival, as well as histologic parameters and intragraft expression of tolerance-associated transcripts in 1-year protocol biopsies were similar in the two groups. In conclusion, pretransplant MSC infusion in liver transplant recipients was safe and induced mild positive changes in immunoregulatory T and NK cells in the peripheral blood. This study opens the way for a trial on possible tolerogenic efficacy of MSC in liver transplantation. ClinicalTrials.gov identifier: NCT02260375.

The Efficacy of Cell-Assisted Lipotransfer Versus Conventional Lipotransfer in Breast Augmentation: A Systematic Review and Meta-Analysis

BACKGROUND

Cell-assisted lipotransfer (CAL) is novel and controversial technique for breast augmentation.

OBJECTIVE

This review and meta-analysis aimed to assess the clinical efficacy of CAL as compared with conventional lipotransfer.

METHODS

PubMed databases were searched with no restrictions for randomized controlled trials (RCTs) and observational studies with control groups. Keywords included "fat graft," "lipotransfer," "lipofilling," "autologous fat," "fat transplantation," "stromal vascular fraction (SVF)," "stem cell," "adipose tissue-derived stromal cell (ADSC)," "adipose tissue-derived stromal cell (ASC)," "called adipose derived progenitor cells (ADRC)," "cell-assisted," "progenitor-enriched," "cell-enhanced" and "breast." Review Manager software (RevMan, version 5.3) was used to compute the pooled effect estimates for fat survival rate and complication rates. Outcomes were expressed as standard mean differences (SMDs) or odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses were performed based on different methods of cell-enhanced fat preparation.

RESULTS

Six studies were included (n_total = 353 adult patients). The fat survival rate was significantly higher in the CAL group than in the control group (SMD = 1.79, 95% CI = 0.28, 3.31; P = 0.02). There were no significant differences in complication rates between the CAL group and the control group (OR = 1.34, 95% CI = 0.65, 2.73; P = 0.43). Subgroup analyses found no significant differences between the SVF and control groups in fat survival rate (SMD = 1.52, 95% CI = -0.21, 3.24; P = 0.08) among both manual and automatic subgroups (P = 0.28 and P = 0.10, respectively). The data analysis showed a significant heterogeneity between manual and automatic subgroups (I² = 57.0%, P = 0.15).

CONCLUSION

This study suggests that cell-assisted lipotransfer is superior to conventional lipotransfer for improved fat survival rate in breast augmentation. However, analyses comparing the SVF-enhanced fat graft with the conventional fat graft noted no differences in fat survival rate. It is necessary to determine which protocol is most beneficial for patients, establish standardized methods of SVF isolation or adipose tissue-derived stromal cells (ADSCs) culture, and a constant percentage of injected cells in the graft. The long-term efficacy and safety of CAL should also be evaluated in further studies, and additional RCTs with larger sample sizes and better comparability are needed.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Macro-encapsulation of mesenchymal stem cells in acute and chronic liver injury animal models

BACKGROUND AND AIM

Stem cell treatments using scaffolds for liver disease have been well studied. However, macro-encapsulation of mesenchymal stem cells (MSCs) to minimize or inhibit stem cell homing has not been evaluated. Here, we conducted a proof-of-concept study using MSCs macro-encapsulated in poly lactic-co-glycolic acid in liver disease models.

METHODS

Poly lactic-co-glycolic acid semipermeable membranes (surface pore size up to 40 μm) were used as the macro-encapsulation system. Macro-encapsulated pouches were loaded with MSCs and sealed. Each pouch was implanted in the subcutaneous region of the dorsum or interlobular space of the liver. Acute liver injury was induced using thioacetamide intraperitoneal injection thrice a week. For the chronic liver fibrosis model, thioacetamide dose was gradually increased, starting from 100 to 400 mg/kg over 16 weeks (thrice a week).

RESULTS

In the acute liver injury model, the treated groups showed decreased liver inflammation and necrosis compared with the control. Hepatic fibrosis decreased in the treated group in the chronic liver fibrosis model compared with that in the control group. Encapsulated MSCs exhibited changed cell morphology and characteristics after implantation, showing increased periodic acid-Schiff staining and CYP2E1 expression. Migration and homing of MSCs into the liver was not observed. Under hypoxic conditions, macro-encapsulated MSCs secreted more growth hormones, including vascular endothelial growth factor, platelet-derived growth factor, angiopoietin-2, and placental growth factor, than monolayered MSCs in vitro.

CONCLUSIONS

Macro-encapsulated MSCs attenuate hepatic inflammation and fibrosis by upregulating hypoxia-induced growth hormone secretion in liver disease models.

A systematic review of intracavernosal injection of mesenchymal stem cells for diabetic erectile dysfunction

BACKGROUND As current erectile dysfunction (ED) treatments are limited, other treatment such as stem cells should be explored. Hence, this study aimed to review the sources, method of administration, and therapeutic effect of mesenchymal stem cells (MSCs) for diabetic ED treatment. METHODS All relevant articles regarding the use of MSCs for diabetic ED were searched in PubMed and Google Scholar databases from December 15, 2019 to January 1, 2020 published in the past 10 years. The keywords were “mesenchymal stem cells” and “diabetic ED”. The selection and critical appraisal of the studies were discussed. Diabetic ED was evaluated for functional and structural outcome. Functional outcome in animal studies was assessed by intracavernosal pressure/mean arterial pressure (ICP/MAP) ratio, meanwhile the structural outcome was done microscopically. In human study, the assessments were done using international index of erectile function score (IIEF-5) to erection hardness score and penile Doppler ultrasonography. RESULTS There were 10 animal studies and 3 human studies. The studies used MSCs from adipose (n = 6), bone marrow (n = 4), placenta (n = 1), umbilical cord (n = 1), and muscle tissue (n = 1). The MSCs were administrated through intracavernosal injection in all studies. In all animal studies, functional outcome was improved, shown in higher ICP/MAP ratio. Microscopically, there were an increase of cavernosal endothelial cells, vascular endothelial growth factor, nitric oxide synthase, and smooth muscle cells. In human studies, IIEF-5 and erection hardness score were improved. Peak systolic velocity was also higher. CONCLUSIONS MSCs may be a promising therapy for diabetic ED; however, long-term safety concerns still need further investigations.

Role of regenerative therapies on erectile dysfunction after radical prostatectomy

The present study provides a review of stem cell therapy as a treatment of erectile dysfunction from peer-reviewed human and animal trials. A literature search was conducted in PubMed-Medline, Scopus, Embase, and Cochrane databases. Tweenty-three animal studies and seven human studies in the period from 1st of January 2000 to 1st of Mai 2020 were included. The seven included human studies are primary phase one trials, and most of them treat erectile dysfunction following radical prostatectomy by injection of stem cells into the corpus cavernosum. The primary outcome measure in all human trials is safety and secondary can stem cells play a role in the recovery of erectile function. All studies conclude that it is safe to use stem cells and the majority of the studies demonstrate an improvement in erectile function. The results from both animal and human trials are promising for stem cells as a restorative treatment, but data from large randomized human phase two trials is missing before it can be concluded, that stem cells is an effective treatment for erectile dysfunction in humans.

Anatomy, Pathophysiology, Molecular Mechanisms, and Clinical Management of Erectile Dysfunction in Patients Affected by Coronary Artery Disease: A Review

Erectile dysfunction (ED) has been defined as the inability to attain or maintain penile erection sufficient for successful sexual intercourse. ED carries a notable influence on life quality, with significant implications for family and social relationships. Because atherosclerosis of penile arteries represents one of the most frequent ED causes, patients presenting with it should always be investigated for potential coexistent coronary or peripheral disease. Up to 75% of ED patients have a stenosis of the iliac-pudendal-penile arteries, supplying the male genital organ’s perfusion. Recently, pathophysiology and molecular basis of male erection have been elucidated, giving the ground to pharmacological and mechanical revascularization treatment of this condition. This review will focus on the normal anatomy and physiology of erection, the pathophysiology of ED, the relation between ED and cardiovascular diseases, and, lastly, on the molecular basis of erectile dysfunction.

Mesenchymal Stromal Cell Therapy in Solid Organ Transplantation

Transplantation is the gold-standard treatment for the failure of several solid organs, including the kidneys, liver, heart, lung and small bowel. The use of tailored immunosuppressive agents has improved graft and patient survival remarkably in early post-transplant stages, but long-term outcomes are frequently unsatisfactory due to the development of chronic graft rejection, which ultimately leads to transplant failure. Moreover, prolonged immunosuppression entails severe side effects that severely impact patient survival and quality of life. The achievement of tolerance, i.e., stable graft function without the need for immunosuppression, is considered the Holy Grail of the field of solid organ transplantation. However, spontaneous tolerance in solid allograft recipients is a rare and unpredictable event. Several strategies that include peri-transplant administration of non-hematopoietic immunomodulatory cells can safely and effectively induce tolerance in pre-clinical models of solid organ transplantation. Mesenchymal stromal cells (MSC), non-hematopoietic cells that can be obtained from several adult and fetal tissues, are among the most promising candidates. In this review, we will focus on current pre-clinical evidence of the immunomodulatory effect of MSC in solid organ transplantation, and discuss the available evidence of their safety and efficacy in clinical trials.

Erectile Dysfunction Treatment Using Stem Cells: A Review

Erectile dysfunction (ED) is a disorder that affects the quality of life and the sexual relations of more than half of the male population aged over 40 years. The prediction regarding the incidence of ED is devastating as it is expected that this disorder will affect more than 300 million men in the next five years. Several studies have suggested the use of stem cells for the treatment of ED and showed that this type of treatment is promising in terms of damaged tissue repair as well as of clinical efficacy; however, there are several gaps in the knowledge and evidence is lacking. In order to highlight a few of them in this review, we performed a research of the literature focusing on currently available clinical studies regarding the clinical efficacy of stem cell administration for the treatment of ED. We reviewed the methods of administration, the cell types used in the performed clinical trials and the safety and efficiency of such procedures. We conclude that there are rapidly expanding and promising results from the reported clinical studies indicating that stem cells could indeed be a potential treatment for patients with ED although more studies are necessary.

Mesenchymal Stromal Cell-Based Therapy: A Promising Approach for Severe COVID-19

During the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), many critically ill patients died of severe pneumonia, acute respiratory distress syndrome (ARDS), or multiple organ dysfunction syndrome. To date, no specific treatments have been proven to be effective for coronavirus disease 2019 (COVID-19). In the animal models and clinical applications, mesenchymal stromal/stem cells (MSCs) have been shown safety and efficacy for the treatment of respiratory virus infection through their abilities of differentiation and immunomodulation. Besides, possessing several advantages of MSC-derived extracellular vesicles (EVs) over MSCs, EV-based therapy also holds potential therapeutic effects in respiratory virus infection. In this review, we summarized the basic characteristics and mechanisms of COVID-19 and MSCs, outlined some preclinical and clinical studies of MSCs or MSC-EVs for respiratory virus infection such as influenza virus and SARS-CoV-2, shed light on the common problems that we should overcome to translate MSC therapy into clinical application, and discussed some safe issues related to the use of MSCs.

From Mesenchymal Stromal/Stem Cells to Insulin-Producing Cells: Progress and Challenges

Mesenchymal stromal cells (MSCs) are an attractive option for cell therapy for type 1 diabetes mellitus (DM). These cells can be obtained from many sources, but bone marrow and adipose tissue are the most studied. MSCs have distinct advantages since they are nonteratogenic, nonimmunogenic and have immunomodulatory functions. Insulin-producing cells (IPCs) can be generated from MSCs by gene transfection, gene editing or directed differentiation. For directed differentiation, MSCs are usually cultured in a glucose-rich medium with various growth and activation factors. The resulting IPCs can control chemically-induced diabetes in immune-deficient mice. These findings are comparable to those obtained from pluripotent cells. PD-L1 and PD-L2 expression by MSCs is upregulated under inflammatory conditions. Immunomodulation occurs due to the interaction between these ligands and PD-1 receptors on T lymphocytes. If this function is maintained after differentiation, life-long immunosuppression or encapsulation could be avoided. In the clinical setting, two sites can be used for transplantation of IPCs: the subcutaneous tissue and the omentum. A 2-stage procedure is required for the former and a laparoscopic procedure for the latter. For either site, cells should be transplanted within a scaffold, preferably one from fibrin. Several questions remain unanswered. Will the transplanted cells be affected by the antibodies involved in the pathogenesis of type 1 DM? What is the functional longevity of these cells following their transplantation? These issues have to be addressed before clinical translation is attempted. Graphical Abstract Bone marrow MSCs are isolated from the long bone of SD rats. Then they are expanded and through directed differentiation insulin-producing cells are formed. The differentiated cells are loaded onto a collagen scaffold. If one-stage transplantation is planned, a drug delivery system must be incorporated to ensure immediate oxygenation, promote vascularization and provide some growth factors. Some mechanisms involved in the immunomodulatory function of MSCs. These are implemented either by cell to cell contact or by the release of soluble factors. Collectively, these pathways results in an increase in T-regulatory cells.

Mesenchymal Stem Cell Therapy for Diabetic Kidney Disease: A Review of the Studies Using Syngeneic, Autologous, Allogeneic, and Xenogeneic Cells

Diabetic kidney disease (DKD) is a microvascular complication of diabetes mellitus (DM) and comprises multifactorial pathophysiologic mechanisms. Despite current treatment, around 30-40% of individuals with type 1 and type 2 DM (DM1 and DM2) have progressive DKD, which is the most common cause of end-stage chronic kidney disease worldwide. Mesenchymal stem cell- (MSC-) based therapy has important biological and therapeutic implications for curtailing DKD progression. As a chronic disease, DM may impair MSC microenvironment, but there is compelling evidence that MSC derived from DM1 individuals maintain their cardinal properties, such as potency, secretion of trophic factors, and modulation of immune cells, so that both autologous and allogeneic MSCs are safe and effective. Conversely, MSCs derived from DM2 individuals are usually dysfunctional, exhibiting higher rates of senescence and apoptosis and a decrease in clonogenicity, proliferation, and angiogenesis potential. Therefore, more studies in humans are needed to reach a conclusion if autologous MSCs from DM2 individuals are effective for treatment of DM-related complications. Importantly, the bench to bedside pathway has been constructed in the last decade for assessing the therapeutic potential of MSCs in the DM setting. Laboratory research set the basis for establishing further translation research including preclinical development and proof of concept in model systems. Phase I clinical trials have evaluated the safety profile of MSC-based therapy in humans, and phase II clinical trials (proof of concept in trial participants) still need to answer important questions for treating DKD, yet metabolic control has already been documented. Therefore, randomized and controlled trials considering the source, optimal cell number, and route of delivery in DM patients are further required to advance MSC-based therapy. Future directions include strategies to reduce MSC heterogeneity, standardized protocols for isolation and expansion of those cells, and the development of well-designed large-scale trials to show significant efficacy during a long follow-up, mainly in individuals with DKD.

Regulation of intracellular transition metal ion level with a pH-sensitive inorganic nanocluster to improve therapeutic angiogenesis by enriching conditioned medium retrieved from human adipose derived stem cells

Cell therapy based on human adipose derived stem cells (hADSCs) is a known potential therapeutic approach to induce angiogenesis in ischemic diseases. However, the therapeutic efficacy of direct hADSC injection is limited by a low cell viability and poor cell engraftment after administration. To improve the outcomes of this kind of approach, various types of nanoparticles have been utilized to improve the therapeutic efficacy of hADSC transplantation. Despite their advantages, the adverse effects of nanoparticles, such as genetic damage and potential oncogenesis based on non-degradable property of nanoparticles prohibit the application of nanoparticles toward the clinical applications. Herein, we designed a transition metal based inorganic nanocluster able of pH-selective degradation (ps-TNC), with the aim of enhancing an hADSC based treatment of mouse hindlimb ischemia. Our ps-TNC was designed to undergo degradation at low pH conditions, thus releasing metal ions only after endocytosis, in the endosome. To eliminate the limitations of both conventional hADSC injection and non-degradable property of nanoparticles, we have collected conditioned medium (CM) from the ps-TNC treated hADSCs and administrated it to the ischemic lesions. We found that intracellular increment of transition metal ion upregulated the hypoxia-inducible factor 1α, which can induce vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) expressions. Based on the molecular mechanism, the secretion of VEGF and bFGF by ps-TNC treated hADSCs showed a significant improvement compared to that of untreated cells. Injecting the CM collected from ps-TNC treated hADSCs into the mouse hindlimb ischemia model (ps-TNC-CM group) showed significantly improved angiogenesis in the lesions, with improved limb salvage and decreased muscle degeneration compared to the group injected with CM collected from normal hADSCs (CM group). This study suggests a novel strategy, combining a known angiogenesis molecular mechanism with both an improvement on conventional stem cell therapy and the circumvention of some limitations still present in modern approaches based on nanoparticles.

Fat grafts enriched with adipose-derived stem cells

Autologous fat grafts are widely used in soft-tissue augmentation and reconstruction. To reduce the unpredictability of fat grafts and to improve their long-term survival, cell-assisted lipotransfer (CAL) was introduced. In this alternative method, autologous fat is mixed and grafted with stromal vascular fraction cells or adipose-derived stem/stromal cells (ASCs). In regenerative medicine, ASCs exhibit excellent therapeutic potential and are also simple to harvest. Although the efficacy of CAL has been demonstrated in experimental and clinical research, studies on its safety in terms of oncologic risk have reported inconclusive results. In order to establish CAL as a viable stem cell therapeutic approach, it will be necessary to demonstrate its oncologic safety in basic and clinical studies. Doing so could transform the paradigm of clinical strategy and practice for the treatment of a wide variety of diseases.

Ex vivo-expanded autologous adipose tissue-derived stromal cells ensure enhanced fat graft retention in breast augmentation: A randomized controlled clinical trial

Autologous fat grafting and implant surgery are used for volume restoration in plastic surgery. With the aim of producing a treatment superior to current solutions, we report a randomized, controlled, data assessor‐blinded clinical trial comparing fat grafts enriched with ex vivo‐expanded autologous adipose‐derived stromal cells (ASCs) to nonenriched fat grafts in breast augmentation. The intervention group received ASC‐enriched fat grafts (≥20 × 10⁶ viable ex vivo‐expanded ASCs per milliliter fat), and the control group received conventional nonenriched fat grafts. Volume retention was measured by magnetic resonance imaging, and clinical photographs were taken simultaneously for outcome evaluation. ASC‐enriched fat grafts had significantly higher retention rates (mean = 80.2%) compared with conventional fat grafts (mean = 45.1%). Clinical photos showed statistically significant superior results in the intervention group, assessed by independent clinical experts. These results improve the prospects for using culture‐expanded ASCs in both reconstructive and cosmetic volume restoration and make the procedure an attractive alternative to conventional fat grafting and implants. This study is registered at www.ClinicalTrials.gov, number H‐16046960.

Targeted Delivery of Mesenchymal Stem Cell-Derived Nanovesicles for Spinal Cord Injury Treatment

Due to the safety issues and poor engraftment of mesenchymal stem cell (MSC) implantation, MSC-derived exosomes have been spotlighted as an alternative therapy for spinal cord injury (SCI). However, insufficient productivity of exosomes limits their therapeutic potential for clinical application. Moreover, low targeting ability of unmodified exosomes is a critical obstacle for their further applications as a therapeutic agent. In the present study, we fabricated macrophage membrane-fused exosome-mimetic nanovesicles (MF-NVs) from macrophage membrane-fused umbilical cord blood-derived MSCs (MF-MSCs) and confirmed their therapeutic potential in a clinically relevant mouse SCI model (controlled mechanical compression injury model). MF-NVs contained larger quantity of ischemic region-targeting molecules compared to normal MSC-derived nanovesicles (N-NVs). The targeting molecules in MF-NVs, which were derived from macrophage membranes, increased the accumulation of MF-NVs in the injured spinal cord after the in vivo systemic injection. Increased accumulation of MF-NVs attenuated apoptosis and inflammation, prevented axonal loss, enhanced blood vessel formation, decreased fibrosis, and consequently, improved spinal cord function. Synthetically, we developed targeting efficiency-potentiated exosome-mimetic nanovesicles and present their possibility of clinical application for SCI.

In vitro efficacy of liver microenvironment in bone marrow mesenchymal stem cell differentiation

Bone marrow-derived mesenchymal stem cells (BM-MSCs) represent an interesting alternative to liver or hepatocyte transplantation to treat liver injuries. Many studies have reported that MSCs can treat several diseases, including liver damage, just by injection into the bloodstream, without evidence of differentiation. The improvements were attributed to the organotrophic factors, low immunogenicity, immunomodulatory, and anti-inflammatory effects of MSCs, rather than their differentiation. The aim of the present study was to answer the question of whether the presence of BM-MSCs in the hepatic microenvironment will lead to their differentiation to functional hepatocyte-like cells. The hepatic microenvironment was mimicked in vitro by culture for 21 d with liver extract. The resulted cells expressed marker genes of the hepatic lineage including AFP, CK18, and Hnf4a. Functionally, they were able to detoxify ammonia into urea, to store glycogen as observed by PAS staining, and to synthesize glucose from pyruvate/lactate mixture. Phenotypically, the expression of MSC surface markers CD90 and CD105 decreased by differentiation. This evidenced differentiation into hepatocyte-like cells was accompanied by a downregulation of the stem cell marker genes sox2 and Nanog and the cell cycle regulatory genes ANAPC2, CDC2, Cyclin A1, and ABL1. The present results suggest a clear differentiation of BM-MSCs into functional hepatocyte-like cells by the extracted liver microenvironment. This differentiation is confirmed by a decrease in the stemness and mitotic activities. Tracking transplanted BM-MSCs and proving their in vivo differentiation remains to be elucidated.

Intrathecal injection of bone marrow stromal cells attenuates neuropathic pain via inhibition of P2X4R in spinal cord microglia

Background

Neuropathic pain is one of the most debilitating of all chronic pain syndromes. Intrathecal (i.t.) bone marrow stromal cell (BMSC) injections have a favorable safety profile; however, results have been inconsistent, and complete understanding of how BMSCs affect neuropathic pain remains elusive.

Methods

We evaluated the analgesic effect of BMSCs on neuropathic pain in a chronic compression of the dorsal root ganglion (CCD) model. We analyzed the effect of BMSCs on microglia reactivity and expression of purinergic receptor P2X₄ (P2X₄R). Furthermore, we assessed the effect of BMSCs on the expression of transient receptor potential vanilloid 4 (TRPV4), a key molecule in the pathogenesis of neuropathic pain, in dorsal root ganglion (DRG) neurons.

Results

I.t. BMSC transiently but significantly ameliorated neuropathic pain behavior (37.6% reduction for 2 days). We found no evidence of BMSC infiltration into the spinal cord parenchyma or DRGs, and we also demonstrated that intrathecal injection of BMSC-lysates provides similar relief. These findings suggest that the analgesic effects of i.t. BMSC were largely due to the release of BMSC-derived factors into the intrathecal space. Mechanistically, we found that while i.t. BMSCs did not change TRPV4 expression in DRG neurons, there was a significant reduction of P2X₄R expression in the spinal cord microglia. BMSC-lysate also reduced P2X₄R expression in activated microglia in vitro. Coadministration of additional pharmacological interventions targeting P2X₄R confirmed that modulation of P2X₄R might be a key mechanism for the analgesic effects of i.t. BMSC.

Conclusion

Altogether, our results suggest that i.t. BMSC is an effective and safe treatment of neuropathic pain and provides novel evidence that BMSC’s analgesic effects are largely mediated by the release of BMSC-derived factors resulting in microglial P2X₄R downregulation.

Fat Extract Improves Random Pattern Skin Flap Survival in a Rat Model

BACKGROUND

Adipose tissue and its derivatives, including adipose-derived stem cells, stromal vascular fraction (SVF), and SVF-gel, have been utilized in the treatment of many ischemic disorders. However, the utilization of these products is limited in clinical applications by concerns related to the presence of cells in these derivatives.

OBJECTIVES

This study aimed to isolate a cell-free fat extract (FE) from fat tissue and to evaluate its proangiogenic ability in vitro as well as its protective effects on skin flap survival in vivo.

METHODS

FE was isolated from human fat via a mechanical approach. The concentrations of several growth factors in the FE were determined by enzyme-linked immunosorbent assay. The proangiogenic ability of FE was evaluated utilizing assays of the proliferation, migration, and tube formation in human umbilical vein endothelial cells in vitro. The protective effects of FE on the survival of random pattern skin flaps were investigated by subcutaneous injection into rats.

RESULTS

Enzyme-linked immunosorbent assay results revealed that FE contained proangiogenic growth factors that promoted proliferation, migration, and tube formation in human umbilical vein endothelial cells in vitro. In addition, FE reduced skin flap necrosis and increased survival, as demonstrated by macroscopic measurements and blood flow analysis. Histological analysis revealed that FE treatment increased the capillary density.

CONCLUSIONS

FE is a cell-free, easy-to-prepare, and growth-factor-enriched liquid derived from human adipose tissue that possesses proangiogenic activity and improves skin flap survival by accelerating blood vessel formation. FE may be potentially used for treating ischemic disorders.

Deciduous autologous tooth stem cells regenerate dental pulp after implantation into injured teeth

Pulp necrosis arrests root development in injured immature permanent teeth, which may result in tooth loss. However, dental pulp regeneration and promotion of root development remains challenging. We show that implantation of autologous tooth stem cells from deciduous teeth regenerated dental pulp with an odontoblast layer, blood vessels, and nerves in two animal models. These results prompted us to enroll 40 patients with pulp necrosis after traumatic dental injuries in a randomized, controlled clinical trial. We randomly allocated 30 patients to the human deciduous pulp stem cell (hDPSC) implantation group and 10 patients to the group receiving traditional apexification treatment. Four patients were excluded from the implantation group due to loss at follow-up (three patients) and retrauma of the treated tooth (one patient). We examined 26 patients (26 teeth) after hDPSC implantation and 10 patients (10 teeth) after apexification treatment. hDPSC implantation, but not apexification treatment, led to regeneration of three-dimensional pulp tissue equipped with blood vessels and sensory nerves at 12 months after treatment. hDPSC implantation increased the length of the root (P < 0.0001) and reduced the width of the apical foramen (P < 0.0001) compared to the apexification group. In addition, hDPSC implantation led to regeneration of dental pulp tissue containing sensory nerves. To evaluate the safety of hDPSC implantation, we followed 20 patients implanted with hDPSCs for 24 months and did not observe any adverse events. Our study suggests that hDPSCs are able to regenerate whole dental pulp and may be useful for treating tooth injuries due to trauma.

Equivalent 10-Year Outcomes After Implantation of Autologous Bone Marrow-Derived Mesenchymal Stem Cells Versus Autologous Chondrocyte Implantation for Chondral Defects of the Knee

BACKGROUND

The use of bone marrow-derived mesenchymal stem cells (BMSCs) in cartilage repair procedures circumvents some of the limitations of autologous chondrocyte implantation (ACI), but long-term outcomes for this newer procedure are lacking. The authors previously reported comparable outcomes for the 2 procedures at 2-year follow-up.

PURPOSE/HYPOTHESIS

The purpose was to compare the long-term clinical outcomes of ACI versus BMSCs. It was hypothesized that there would be no significant difference between the groups in terms of patient-reported outcome scores and safety outcomes at 10-year follow-up.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Seventy-two patients who underwent either ACI or BMSC implantation-matched in terms of age and lesion site- were followed up to a median of at least 10 years. Patients were assessed with the 36-item Short Form Health Survey (SF-36), the International Knee Documentation Committee knee evaluation form, the Lysholm Knee Score, and the Tegner Activity Scale. In addition, information was obtained regarding any additional surgical procedures as well as safety data, with particular attention to infection and tumor formation.

RESULTS

There was an improvement in all patient-reported outcomes scores apart from the Mental Component Summary of the SF-36 after cartilage repair surgery. There was no significant difference in any of the patient-reported outcomes between cohorts at any time point. Six and 5 patients in the ACI and BMSC groups, respectively, underwent subsequent surgical procedures, including 1 total knee replacement in the BMSC group. None of the patients in either group developed any deep infection or tumor within the follow-up period.

CONCLUSION

BMSC implantation used for the treatment of chondral defects of the knee appears to result in equivalent clinical outcomes to first-generation ACI at up to 10 years, with no apparent increased tumor formation risk.

Human amnion epithelial cells and their soluble factors reduce liver fibrosis in murine non-alcoholic steatohepatitis

BACKGROUND AND AIM

Non-alcoholic steatohepatitis (NASH) can lead to cirrhosis and hepatocellular carcinoma. Currently, lifestyle modification is the only effective treatment. We have shown that human amnion epithelial cells (hAECs) reduce inflammation and fibrosis in toxin-induced liver injury models. We examined the effect of these cells and the soluble factors released by the cells into culture medium (hAEC conditioned medium [hAEC-CM]) in a diet-induced murine NASH model.

METHODS

C57BL/6J male mice received a Western "fast food diet" for 42 weeks. Group 1 received an intraperitoneal injection of 2 × 10⁶ hAECs at week 34, group 2 received an additional hAEC dose at week 38, and group 3 received thrice weekly hAEC-CM injections intraperitoneal for 8 weeks from week 34. Liver fibrosis area, inflammation, and fibrosis regulators were measured by immunohistochemistry, qPCR, and gelatin zymography. Metabolic parameters were also assessed.

RESULTS

Fast food diet-fed mice demonstrated peri-cellular hepatic fibrosis, inflammation, and steatosis typical of NASH. Liver fibrosis area was reduced by 40% in hAEC-treated and hAEC-CM-treated mice. hAEC treatment significantly reduced pSMAD 2/3 signaling and the number of activated hepatic stellate cells and liver macrophages. Matrix metalloproteinase 2 and 9 gene and protein expression were variably affected. hAEC treatment did not alter the NASH activity score or metabolic parameters such as bodyweight, total cholesterol, or glucose tolerance.

CONCLUSION

Human amnion epithelial cell and hAEC-CM significantly reduced hepatic inflammation and fibrosis in a diet-induced non-alcoholic fatty liver disease model. Although hAEC and hAEC-CM did not affect the metabolic components of NASH, their therapeutic potential is promising and warrants further investigation.

Stem Cell Therapies in Kidney Diseases: Progress and Challenges

The prevalence of renal diseases is emerging as a public health problem. Despite major progress in supportive therapy, mortality rates among patients remain high. In an attempt to find innovative treatments to stimulate kidney regeneration, stem cell-based technology has been proposed as a potentially promising strategy. Here, we summarise the renoprotective potential of pluripotent and adult stem cell therapy in experimental models of acute and chronic kidney injury and we explore the different mechanisms at the basis of stem cell-induced kidney regeneration. Specifically, cell engraftment, incorporation into renal structures, or paracrine activities of embryonic or induced pluripotent stem cells as well as mesenchymal stem cells and renal precursors are analysed. We also discuss the relevance of stem cell secretome-derived bioproducts, including soluble factors and extracellular vesicles, and the option of using them as cell-free therapy to induce reparative processes. The translation of the experimental results into clinical trials is also addressed, highlighting the safety and feasibility of stem cell treatments in patients with kidney injury.

Mesenchymal Stromal Cells for Transplant Tolerance

In solid organ transplantation lifelong immunosuppression exposes transplant recipients to life-threatening complications, such as infections and malignancies, and to severe side effects. Cellular therapy with mesenchymal stromal cells (MSC) has recently emerged as a promising strategy to regulate anti-donor immune responses, allowing immunosuppressive drug minimization and tolerance induction. In this review we summarize preclinical data on MSC in solid organ transplant models, focusing on potential mechanisms of action of MSC, including down-regulation of effector T-cell response and activation of regulatory pathways. We will also provide an overview of available data on safety and feasibility of MSC therapy in solid organ transplant patients, highlighting the issues that still need to be addressed before establishing MSC as a safe and effective tolerogenic cell therapy in transplantation.

Bone marrow-derived mesenchymal stem cells promote colorectal cancer progression via CCR5

Mesenchymal stem cells (MSCs) are recruited from BM to the stroma of developing tumors, where they serve as critical components of the tumor microenvironment by secreting growth factors, cytokines, and chemokines. The role of MSCs in colorectal cancer (CRC) progression was controversial. In this study, we found that C-C chemokine receptor type 5 (CCR5) ligands (i.e., C-C motif chemokine ligand 3 (CCL3), CCL4, and CCL5) were highly produced from MSCs using a chemokine array screening with conditioned media from the cultured human MSCs. A relatively strong CCR5 expression could be detected within the cytoplasm of several CRC cell lines. Regarding the effect of MSC, we found that the xenografts in which CCR5-overexpressing HCT116 cells were inoculated into immunocompromised mice were highly promoted in vivo by a mixture with MSCs. Notably, the CCR5 inhibitor, maraviroc, significantly abolished the MSC-induced tumor growth in vivo. In human clinical specimens (n = 89), 20 cases (29%) were high for CCR5, whereas 69 cases (71%) were low. Statistical analyses indicated that CCR5 expression in primary CRC was associated with CRC patients’ prognosis. Especially, stage III/IV patients with CCR5-high CRCs exhibited a significantly poorer prognosis than those with CCR5-low CRCs. Furthermore, we investigated the effects of preoperative serum CCR5 ligands on patients’ prognosis (n = 114), and found that CRC patients with high serum levels of CCL3 and CCL4 exhibited a poorer prognosis compared to those with low levels of CCL3 and CCL4, while there was no association between CCL5 and prognosis. These results suggest that the inhibition of MSC–CRC interaction by a CCR5 inhibitor could provide the possibility of a novel therapeutic strategy for CRC, and that serum levels of CCL3 and CCL4 could be predictive biomarkers for the prognosis of CRC patients.