Phase II Multicenter, Randomized, Double-Blind Controlled Study of Efficacy and Safety of Umbilical Cord-Derived Mesenchymal Stromal Cells in the Prophylaxis of Chronic Graft-Versus-Host Disease After HLA-Haploidentical Stem-Cell Transplantation

Safety and efficacy of umbilical cord tissue-derived mesenchymal stem cells in the treatment of patients with aging frailty: a phase I/II randomized, double-blind, placebo-controlled study

BACKGROUND

Mesenchymal stem cells (MSCs) hold a great promise for cell-based therapy in the field of regenerative medicine. In this study, we aimed to evaluate the safety and efficacy of intravenous infusion of human umbilical cord-derived MSCs (HUC-MSCs) in patients with aging frailty.

METHODS

In this randomized, double-blind, placebo-controlled trial, participants diagnosed with aging frailty were randomly assigned to receive intravenous administrations of HUC-MSCs or placebo. All of serious adverse events and AEs were monitored to evaluate the safety of treatment during the 6-month follow-up. The primary efficacy endpoint was alteration of physical component scores (PCS) of SF-36 qualities of life at 6 months. The secondary outcomes including physical performance tests and pro-inflammatory cytokines, were also observed and compared at each follow-up visits. All evaluations were performed at 1 week, 1, 2, 3 and 6 months following the first intravenous infusion of HUC-MSCs.

RESULTS

In the MSCs group, significant improvements in PCS of SF-36 were observed from first post-treatment visit and sustained throughout the follow-up period, with greater changes compared to the placebo group (p = 0.042). EQ-VAS scores of MSCs group improved significantly at 2 month (p = 0.023) and continued until the end of the 6-month visit (p = 0.002) in comparison to the placebo group. The timed up and go (TUG) physical performance test revealed significant group difference and showed continual enhancements over 6 months (p < 0.05). MSC transplantation improved the function of 4-m walking test (4MWT) compared with the placebo group with a decrease of 2.05 s at 6 months of follow-up (p = 0.21). The measurement of grip strength revealed group difference with MSCs group demonstrating better performance, particularly at 6 months (p = 0.002). Inflammatory cytokines (TNF-α, IL-17) exhibited declines in MSCs group at 6 months compared to the placebo group (p = 0.034 and 0.033, respectively). There was no difference of incidence of AEs between the two groups.

CONCLUSION

Intravenous transplantation of HUC-MSCs is a safe and effective therapeutic approach on aging frailty. The positive outcomes observed in improving quality of life, physical performance, and reducing chronic inflammation, suggest that HUC-MSC therapy may be a promising potential treatment option for aging frailty.

TRIAL REGISTRATION

Clinicaltrial.gov; NCT04314011; https://clinicaltrials.gov/ct2/show/NCT04314011 .

Haploidentical haematopoietic stem cell transplantation combined with post-transplant cyclophosphamide in neuronal ceroid lipofuscinosis: Experience in eight patients

BACKGROUND

Neuronal ceroid lipofuscinoses (NCLs) are rare lysosomal storage disorders characterized by progressive mental retardation and motor developmental regression and myoclonic seizures. Hematopoietic stem cell transplantation (HSCT) has been suggested to be used in the treatment of lysosomal disorders and brain damage caused by a deficiency of soluble lysosomal enzymes. There are no previous reports on treating NCLs with HSCT in China.

MATERIAL AND METHOD

NCL pediatric patients who underwent allo-HSCT at Affiliated Children's Hospital of Capital Institute of Pediatrics were involved. A combination of medical histories, clinical features, and genetic analyses was used for the diagnosis of all patients. The written consent form for allo-HSCT was attained from the patient's guardian, which was then reviewed and approved by the ethics committee before the procedure.

RESULTS

From January 2018 to May 2019, the haplo-HSCT followed by PT/Cy on eight NCL pediatric patients was performed. The median age was 4.5 years (ranging from 2.8 to 7 years). The donors were their haploidentical HLA-matched parents, as no identically matched donors were found. The median nucleated cell count was 25.37 (10-34.41)×108/kg, and the median CD34+ count was 13.7 (8.95-22)×106/kg. Neutrophil reconstitution occurred 12 days (11-14 days) after transplantation, and the median platelet reconstitution time was 12 days (9-14 days) after transplantation. All patients achieved full donor chimerism and did not develop Grade II-IV acute GvHD or chronic GvHD after transplantation. The median follow-up period was 2.2 (1.5-2.6) years. All patients are still alive at present and develop no severe transplantation-related complications. The mental motor disorders, myoclonic seizures, and vision loss of all patients continued to progress. However, the progression slowed at 12 months after transplantation.

CONCLUSION

This study demonstrated that it is safe and efficacious to treat NCLs with haplo-HSCT. Transplantation should be performed at an early stage for the survival quality of pediatric patients.

Mesenchymal Stem Cells for Prophylaxis of Chronic Graft-vs-Host Disease After Haploidentical Hematopoietic Stem Cell Transplant: An Open-Label Randomized Clinical Trial

Importance

Chronic graft-vs-host disease (GVHD) limits the long-term benefit of haploidentical hematopoietic stem cell transplant (HSCT). This clinical trial evaluated repeated infusions of umbilical cord mesenchymal stem cells (MSCs) during the early stage (45 days and 100 days) after haplo-HSCT to prevent chronic GVHD.

Objective

To determine whether repeated infusions of MSCs during the early stage after haplo-HSCT decreases the incidence of severe chronic GVHD.

Design, Setting, and Participants

This open-label, multicenter, parallel randomized clinical trial was conducted from April 2016 to January 2022. Eligibility criteria included a diagnosis of acute leukemia and having a haploidentical, suitable related donor for HSCT. The median (range) follow-up time was 39.0 (1.5-67.0) months.

Interventions

The enrolled patients with a haploidentical relative for HSCT received the modified busulfan/cyclophosphamide + antithymocyte globulin modified regimen and standard GVHD prophylaxis. Patients were randomly chosen to receive MSCs (the MSC group) (1 × 106 cells/kg, every 2 weeks, starting from 45 days after transplant, 4 times total) or regular prophylaxis (control group).

Main Outcome and Measure

The cumulative incidence of severe chronic GVHD.

Results

Of 158 patients, 58 (36.7%) were female individuals; the median (range) age for the MSC and control groups was 28 (18-60) years and 28 (18-56) years, respectively. A total of 158 patients were screened, and 148 patients were randomly assigned to the MSC group (n = 74) or control group (n = 74) 1 day before MSCs infusion. The estimated 2-year cumulative incidence of severe chronic GVHD was 5.4% (95% CI, 1.8%-14.0%) in the MSC group and 17.4% (95% CI, 10.1%-28.5%) in the control group (hazard ratio [HR], 0.29; 95% CI, 0.10-0.88; P = .03). There was no difference between the MSC and control groups in the cumulative incidence of leukemia relapse (HR, 1.17; 95% CI, 0.55-2.47; P = .68). The cumulative incidence of stage II to IV acute GVHD in the MSC group was significantly lower than that in the control group (HR, 0.25; 95% CI, 0.09-0.67; P = .01). The MSC group had better GVHD-free and relapse-free survival rates than the control group (HR, 0.62; 95% CI, 0.39-0.98; P = .04).

Conclusions and Relevance

The results of this randomized clinical trial show that early repeated infusions of MSCs decreased the incidence and severity of chronic GVHD, and the incidence and severity of acute GVHD manifested as a better GVHD-free and relapse-free survival rate for patients after haplo-HSCT.

Trial Registration

Chinese Clinical Trial Registry: ChiCTR-IIR-16007806.

Mesenchymal stromal cells, metabolism, and mitochondrial transfer in bone marrow normal and malignant hematopoiesis

Hematopoietic stem cell (HSC) transplantation-based treatments are in different phases of clinical development, ranging from current therapies to a promise in the repair and regeneration of diseased tissues and organs. Mesenchymal stromal/stem cells (MSCs), which are fibroblast-like heterogeneous progenitors with multilineage differentiation (osteogenic, chondrogenic, and adipogenic) and self-renewal potential, and exist in the bone marrow (BM), adipose, and synovium, among other tissues, represent one of the most widely used sources of stem cells in regenerative medicine. MSCs derived from bone marrow (BM-MSCs) exhibit a variety of traits, including the potential to drive HSC fate and anti-inflammatory and immunosuppressive capabilities via paracrine activities and interactions with the innate and adaptive immune systems. The role of BM-MSC-derived adipocytes is more controversial and may act as positive or negative regulators of benign or malignant hematopoiesis based on their anatomical location and functional crosstalk with surrounding cells in the BM microenvironment. This review highlights the most recent clinical and pre-clinical findings on how BM-MSCs interact with the surrounding HSCs, progenitors, and immune cells, and address some recent insights on the mechanisms that mediate MSCs and adipocyte metabolic control through a metabolic crosstalk between BM microenvironment cells and intercellular mitochondrial transfer in normal and malignant hematopoiesis.

Haploidentical transplants with a G-CSF/ATG-based protocol: Experience from China

Haploidentical donor stem cell transplantation (haplo-SCT) has made great advances in recent decades. The granulocyte colony-stimulating factor (G-CSF)- and antithymocyte globulin (ATG)-based protocol, which is known as the Beijing Protocol, represents one of the current T-cell repletion strategies in haplo-SCT. The key elements of the Beijing Protocol for graft versus host disease (GvHD) prophylaxis include G-CSF inducing T-cell tolerance and altering graft cell components, as well as ATG administration exerting an immunoregulatory effect for intensive prophylaxis. This review will summarize the GvHD incidence, the underlying novel mechanism for GvHD prophylaxis, how to optimize GvHD prophylaxis, and the recent advances of the Beijing Protocol, mainly focusing on the issues of GvHD.

Mesenchymal stromal cells ameliorate chronic GVHD by boosting thymic regeneration in a CCR9-dependent manner in mice

Chronic graft-versus-host disease (cGVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Mature donor T cells within the graft contribute to severe damage of thymic epithelial cells (TECs), which are known as key mediators in the continuum of acute GVHD (aGVHD) and cGVHD pathology. Mesenchymal stromal cells (MSCs) are reportedly effective in the prevention and treatment of cGVHD. In our previous pilot clinical trial in patients with refractory aGVHD, the incidence and severity of cGVHD were decreased, along with an increase in levels of blood signal joint T-cell receptor excision DNA circles after MSCs treatment, which indicated an improvement in thymus function of patients with GVHD, but the mechanisms leading to these effects remain unknown. Here, we show in a murine GVHD model that MSCs promoted the quantity and maturity of TECs as well as elevated the proportion of Aire-positive medullary TECs, improving both CD4+CD8+ double-positive thymocytes and thymic regulatory T cells, balancing the CD4:CD8 ratio in the blood. In addition, CCL25-CCR9 signaling axis was found to play an important role in guiding MSC homing to the thymus. These studies reveal mechanisms through which MSCs ameliorate cGVHD by boosting thymic regeneration and offer innovative strategies for improving thymus function in patients with GVHD.

A review of the application of mesenchymal stem cells in the field of hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) is an effective treatment for many malignant hematological diseases. Mesenchymal stem cells (MSCs) are nonhematopoietic stem cells with strong self-renewal ability and multidirectional differentiation potential. They have the characteristics of hematopoietic support, immune regulation, tissue repair and regeneration, and homing. Recent studies have shown that HSCT combined with MSC infusion can promote the implantation of hematopoietic stem cells and enhance the reconstruction of hematopoietic function. Researchers have also found that MSCs have good preventive and therapeutic effects on acute and chronic graft-versus-host disease (GVHD), but there is still a lack of validation in large-sample randomized controlled trials. When using MSCs clinically, it is necessary to consider their dose, source, application time, application frequency and other relevant factors, but the specific impact of the above factors on the efficacy of MSCs still needs further clinical trial research. This review introduces the clinical roles of MSCs and summarizes the most recent progress concerning the use of MSCs in the field of HSCT, providing references for the later application of the combination of MSCs and HSCT in hematological diseases.

The role of MSCs and CAR-MSCs in cellular immunotherapy

Chimeric antigen receptors (CARs) are widely used by T cells (CAR-T cells), natural killer cells dendritic cells and macrophages, and they are of great importance in cellular immunotherapy. However, the use of CAR-related products faces several challenges, including the poor persistence of cells carrying CARs, cell dysfunction or exhaustion, relapse of disease, immune effector cell-associated neurotoxicity syndrome, cytokine release syndrome, low efficacy against solid tumors and immunosuppression by the tumor microenvironment. Another important cell therapy regimen involves mesenchymal stem cells (MSCs). Recent studies have shown that MSCs can improve the anticancer functions of CAR-related products. CAR-MSCs can overcome the flaws of cellular immunotherapy. Thus, MSCs can be used as a biological vehicle for CARs. In this review, we first discuss the characteristics and immunomodulatory functions of MSCs. Then, the role of MSCs as a source of exosomes, including the characteristics of MSC-derived exosomes and their immunomodulatory functions, is discussed. The role of MSCs in CAR-related products, CAR-related product-derived exosomes and the effect of MSCs on CAR-related products are reviewed. Finally, the use of MSCs as CAR vehicles is discussed. Video Abstract.

Engineered Living Materials for Advanced Diseases Therapy

Natural living materials serving as biotherapeutics exhibit great potential for treating various diseases owing to their immunoactivity, tissue targeting, and other biological activities. In this review, the recent developments in engineered living materials, including mammalian cells, bacteria, viruses, fungi, microalgae, plants, and their active derivatives that are used for treating various diseases are summarized. Further, the future perspectives and challenges of such engineered living material-based biotherapeutics are discussed to provide considerations for future advances in biomedical applications.

Clinical utility of mesenchymal stem/stromal cells in regenerative medicine and cellular therapy

Mesenchymal stem/stromal cells (MSCs) have been carefully examined to have tremendous potential in regenerative medicine. With their immunomodulatory and regenerative properties, MSCs have numerous applications within the clinical sector. MSCs have the properties of multilineage differentiation, paracrine signaling, and can be isolated from various tissues, which makes them a key candidate for applications in numerous organ systems. To accentuate the importance of MSC therapy for a range of clinical indications, this review highlights MSC-specific studies on the musculoskeletal, nervous, cardiovascular, and immune systems where most trials are reported. Furthermore, an updated list of the different types of MSCs used in clinical trials, as well as the key characteristics of each type of MSCs are included. Many of the studies mentioned revolve around the properties of MSC, such as exosome usage and MSC co-cultures with other cell types. It is worth noting that MSC clinical usage is not limited to these four systems, and MSCs continue to be tested to repair, regenerate, or modulate other diseased or injured organ systems. This review provides an updated compilation of MSCs in clinical trials that paves the way for improvement in the field of MSC therapy.

Umbilical cord blood derived cellular therapy: advances in clinical development

While cord blood (CB) is primarily utilized in allogeneic hematopoietic cell transplantation (HCT), the development of novel cell therapy products from CB is a growing and developing field. Compared to adult blood, CB is characterized by a higher percentage of hematopoietic stem cells (HSCs) and progenitor cells, less mature immune cells that retain a high capacity of proliferation, and stronger immune tolerance that requires less stringent HLA-matching when used in the allogenic setting. Given that CB is an FDA regulated product and along with its unique cellular composition, CB lends itself as a readily available and safe starting material for the development of off-the-shelf cell therapies. Moreover, non-hematologic cells such as mesenchymal stem cell (MSCs) residing in CB or CB tissue also have potential in regenerative medicine and inflammatory and autoimmune conditions. In this review, we will focus on recent clinical development on CB-derived cellular therapies in the field of oncology, including T-cell therapies such as chimeric antigen receptor (CAR) T-cells, regulatory T-cells, and virus-specific T-cells; NK-cell therapies, such as NK cell engagers and CAR NK-cells; CB-HCT and various modifications; as well as applications of MSCs in HCT.

Current perspectives on mesenchymal stromal cell therapy for graft versus host disease

Graft versus host disease (GvHD) is the clinical condition in which bone marrow-derived mesenchymal stromal cells (MSCs) have been most frequently studied. In this review, we summarize the experience from clinical trials that have paved the way to translation. While MSC-based therapy has shown an exceptional safety profile, identifying potency assays and disease biomarkers that reliably predict the capacity of a specific MSC batch to alleviate GvHD has been difficult. As GvHD diagnosis and staging are based solely on clinical criteria, individual patients recruited in the same clinical trial may have vastly different underlying biology, obscuring trial outcomes and making it difficult to determine the benefit of MSCs in subgroups of patients. An accumulating body of evidence indicates the importance of considering not only the cell product but also patient-specific biomarkers and/or immune characteristics in determining MSC responsiveness. A mode of action where intravascular MSC destruction is followed by monocyte-efferocytosis-mediated skewing of the immune repertoire in a permissive inflammatory environment would both explain why cell engraftment is irrelevant for MSC efficacy and stress the importance of biologic differences between responding and nonresponding patients. We recommend a combined analysis of clinical outcomes and both biomarkers of disease activity and MSC potency assays to identify patients with GvHD who are likely to benefit from MSC therapy.

Harnessing and honing mesenchymal stem/stromal cells for the amelioration of graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation is a deterministic curative procedure for various hematologic disorders and congenital immunodeficiency. Despite its increased use, the mortality rate for patients undergoing this procedure remains high, mainly due to the perceived risk of exacerbating graft-versus-host disease (GVHD). However, even with immunosuppressive agents, some patients still develop GVHD. Advanced mesenchymal stem/stromal cell (MSC) strategies have been proposed to achieve better therapeutic outcomes, given their immunosuppressive potential. However, the efficacy and trial designs have varied among the studies, and some research findings appear contradictory due to the challenges in characterizing the in vivo effects of MSCs. This review aims to provide real insights into this clinical entity, emphasizing diagnostic, and therapeutic considerations and generating pathophysiology hypotheses to identify research avenues. The indications and timing for the clinical application of MSCs are still subject to debate.

Human umbilical cord mesenchymal stem cells ameliorate acute graft versus host disease by elevating phytosphingosine

Acute graft-versus-host disease (aGVHD) is a prominent barrier to allogeneic hematopoietic stem cell transplantation (allo-HSCT) and even leads to death after HSCT. Human umbilical cord mesenchymal stem cells (HUCMSCs) are effective in aGVHD treatment and have mild side effects, but the underlying mechanisms remain unclear. Phytosphingosine (PHS) is known to prevent loss of moisture from the skin; regulate epidermal cell growth, differentiation, and apoptosis; and exert bactericidal and anti-inflammatory effects. In this study, our results revealed the efficacy of HUCMSCs in alleviating aGVHD in a murine model, with striking changes in metabolism and significantly elevated PHS levels due to sphingolipid metabolism. In vitro, PHS reduced CD4⁺ T cell proliferation, enhanced apoptosis and reduced T helper 1 (Th1) cell differentiation. Transcriptional analysis of donor CD4⁺ T cells treated with PHS revealed significant decreases in transcripts regulating proinflammatory pathways, such as NF-κB. In vivo, the administration of PHS significantly ameliorated aGVHD development. Collectively, these beneficial effects indicate proof-of-concept that sphingolipid metabolites could be a safe and effective means to prevent aGVHD in the clinic.

Connexin 43-modified bone marrow stromal cells reverse the imatinib resistance of K562 cells via Ca 2+ -dependent gap junction intercellular communication

BACKGROUND

Imatinib mesylate (IM) resistance is an emerging problem for chronic myeloid leukemia (CML). Previous studies found that connexin 43 (Cx43) deficiency in the hematopoietic microenvironment (HM) protects minimal residual disease (MRD), but the mechanism remains unknown.

METHODS

Immunohistochemistry assays were employed to compare the expression of Cx43 and hypoxia-inducible factor 1α (HIF-1α) in bone marrow (BM) biopsies of CML patients and healthy donors. A coculture system of K562 cells and several Cx43-modified bone marrow stromal cells (BMSCs) was established under IM treatment. Proliferation, cell cycle, apoptosis, and other indicators of K562 cells in different groups were detected to investigate the function and possible mechanism of Cx43. We assessed the Ca 2+ -related pathway by Western blotting. Tumor-bearing models were also established to validate the causal role of Cx43 in reversing IM resistance.

RESULTS

Low levels of Cx43 in BMs were observed in CML patients, and Cx43 expression was negatively correlated with HIF-1α. We also observed that K562 cells cocultured with BMSCs transfected with adenovirus-short hairpin RNA of Cx43 (BMSCs-shCx43) had a lower apoptosis rate and that their cell cycle was blocked in G0/G1 phase, while the result was the opposite in the Cx43-overexpression setting. Cx43 mediates gap junction intercellular communication (GJIC) through direct contact, and Ca 2+ is the key factor mediating the downstream apoptotic pathway. In animal experiments, mice bearing K562, and BMSCs-Cx43 had the smallest tumor volume and spleen, which was consistent with the in vitro experiments.

CONCLUSIONS

Cx43 deficiency exists in CML patients, promoting the generation of MRD and inducing drug resistance. Enhancing Cx43 expression and GJIC function in the HM may be a novel strategy to reverse drug resistance and promote IM efficacy.

Recent advances in ocular graft-versus-host disease

Ocular graft-versus-host-disease (GVHD) remains a significant clinical complication after allogeneic hematopoietic stem cell transplantation. Impaired visual function, pain, and other symptoms severely affect affected individuals' quality of life. However, the diagnosis of and therapy for ocular GVHD involve a multidisciplinary approach and remain challenging for both hematologists and ophthalmologists, as there are no unified international criteria. Through an exploration of the complex pathogenesis of ocular GVHD, this review comprehensively summarizes the pathogenic mechanism, related tear biomarkers, and clinical characteristics of this disease. Novel therapies based on the mechanisms are also discussed to provide insights into the ocular GVHD treatment.

Optimal Intravenous Administration Procedure for Efficient Delivery of Canine Adipose-Derived Mesenchymal Stem Cells

Mesenchymal stem cells (MSC) are currently being investigated for their therapeutic applications in a wide range of diseases. Although many studies examined peripheral venous administration of MSC, few have investigated the detailed intravenous administration procedures of MSC from their preparation until they enter the body. The current study therefore aimed to explore the most efficient infusion procedure for MSC delivery by preparing and infusing them under various conditions. Canine adipose-derived mesenchymal stem cells (cADSC) were infused using different infusion apparatuses, suspension solutions, allogenic serum supplementation, infusion time and rates, and cell densities, respectively. Live and dead cell counts were then assessed by manual measurements and flow cytometry. Efficiency of live- and dead-cell infusion and cell viability were calculated from the measured cell counts and compared under each condition. Efficiency of live-cell infusion differed significantly according to the infusion apparatus, infusion rate, and combination of cell density and serum supplementation. Cell viability after infusion differed significantly between the infusion apparatuses. The optimal infusion procedure resulting in the highest cell delivery and viability involved suspending cADSC in normal saline supplemented with 5% allogenic serum at a density of 5 × 10⁵ cells/mL, and infusing them using an automatic infusion device for 15 min. This procedure is therefore recommended as the standard procedure for the intravenous administration of ADSC in terms of cell-delivery efficiency.

Cellular-Based Therapies in Systemic Sclerosis: From Hematopoietic Stem Cell Transplant to Innovative Approaches

Systemic sclerosis (SSc) is a systemic disease characterized by autoimmune responses, vasculopathy and tissue fibrosis. The pathogenic mechanisms involve a wide range of cells and soluble factors. The complexity of interactions leads to heterogeneous clinical features in terms of the extent, severity, and rate of progression of skin fibrosis and internal organ involvement. Available disease-modifying drugs have only modest effects on halting disease progression and may be associated with significant side effects. Therefore, cellular therapies have been developed aiming at the restoration of immunologic self-tolerance in order to provide durable remissions or to foster tissue regeneration. Currently, SSc is recommended as the 'standard indication' for autologous hematopoietic stem cell transplantation by the European Society for Blood and Marrow Transplantation. This review provides an overview on cellular therapies in SSc, from pre-clinical models to clinical applications, opening towards more advanced cellular therapies, such as mesenchymal stem cells, regulatory T cells and potentially CAR-T-cell therapies.

Mesenchymal stroma/stem cells: Haematologists' friend or foe?

Mesenchymal stromal cells (MSCs) are non-haematopoietic cells found in fetal and adult organs, that play important roles in tissue repair, inflammation and immune modulation. MSCs residing in the bone marrow interact closely with haematopoietic cells and comprise an important component of the microenvironment supporting haematopoiesis, in both health and disease states. Since their identification in 1970, basic scientific and preclinical research efforts have shed light on the role of MSCs in the regulation of haematopoiesis and evoked interest in their clinical application in haematopoietic stem cell transplantation (HSCT) and malignant haematology. Over the last two decades, these research efforts have led to numerous clinical trials, which have established the safety of MSC therapy; however, the optimal mode of administration and the benefit remain inconclusive. In this paper, we will review the clinical experience with use of MSCs in HSCT for enhancement of engraftment, prevention and treatment of graft-versus-host disease and haemorrhagic cystitis. Then, we will discuss the contradictory evidence regarding tumour-promoting versus tumour-suppressing effects of MSCs in haematological malignancies, which may have relevance for future clinical applications.

Immunomodulatory Mechanisms of Mesenchymal Stem Cells and Their Potential Clinical Applications

Mesenchymal stem cells (MSCs) are multipotent stem cells with the capacity of self-renewal, homing, and low immunogenicity. These distinct biological characteristics have already shown immense potential in regenerative medicine. MSCs also possess immunomodulatory properties that can maintain immune homeostasis when the immune response is over-activated or under-activated. The secretome of MSCs consists of cytokines, chemokines, signaling molecules, and growth factors, which effectively contribute to the regulation of immune and inflammatory responses. The immunomodulatory effects of MSCs can also be achieved through direct cell contact with microenvironmental factors and immune cells. Furthermore, preconditioned and engineered MSCs can specifically improve the immunomodulation effects in diverse clinical applications. These multifunctional properties of MSCs enable them to be used as a prospective therapeutic strategy to treat immune disorders, including autoimmune diseases and incurable inflammatory diseases. Here we review the recent exploration of immunomodulatory mechanisms of MSCs and briefly discuss the promotion of the genetically engineered MSCs. Additionally, we review the potential clinical applications of MSC-mediated immunomodulation in four types of immune diseases, including systemic lupus erythematosus, Crohn’s disease, graft-versus-host disease, and COVID-19.

Current status and prospects of hematopoietic stem cell transplantation in China

Hematopoietic stem cell transplantation (HSCT) is a highly effective and unique medical procedure for the treatment of most hematological malignancies. The first allogeneic transplantation was performed by E. Donnall Thomas in 1957. Since then, the field has evolved and expanded worldwide. The first successful allogenic HSCT (allo-HSCT) in China was conducted in 1981. Although the development of allo-HSCT in China lagged, China has since made considerable contributions to the process of HSCT worldwide, with more than 10,000 HSCTs performed annually. In particular, haploid HSCT (haplo-HSCT) technology represented in the Beijing Protocol has demonstrated similar efficacy to human leukocyte antigen-matched HSCT and has gradually become the pre-dominant choice for allo-HSCT in China. Currently, the number of haplo-HSCT procedures exceeds 5000 per year, and the Beijing Protocol has been greatly improved by implementing updated individualized strategies for controlling complications, relapse, and infection management. In addition, innovative haplo-HSCT technologies developed by different medical transplantation centers, such as Soochow, Zhejiang, Fujian, Chongqing, and Anhui, have emerged, providing inspiration for the refinement of global practice. This review will focus on the current activity in this field and highlight important trends that are vital in China's allo-HSCT process, examining the current viewpoint and future directions.

Analysis of the Efficacy and Safety of Avatrombopag Combined With MSCs for the Treatment of Thrombocytopenia After Allogeneic Hematopoietic Stem Cell Transplantation

Platelet graft failure (PGF) is a frequent and serious complication after Allogeneic hematopoietic stem cell transplantation (allo-HSCT) and lacks effective treatment strategies, which could affect the prognosis of patients and even cause death. The exact underlying mechanism of PGF remains unclear, and lacks standard treatment. Here, we conduct a retrospective study to evaluate the efficacy and safety of avatrombopag combined with mesenchymal stem cells (MSCs) in 16 patients with thrombocytopenia after allo-HSCT. Patients were administered the following treatment regimen: 20 mg/d avatrombopag; if the PLT count was less than 50×10^{^}9/L for at least 2 weeks, the dose was increased to 40 mg/d; if the PLT count was 200-400×10^{^}9/L, the dose was reduced; and if the PLT count was greater than 400×10^9/L, avatrombopag was terminated. Umbilical cord MSCs (1×10^{^}6 cells/kg) infusion was performed every week for 4-6 weeks. Among the 16 patients, 13 patients (81.3%) achieved a complete response (CR), 2 patients (12.5%) got a partial response (PR), and 1 patient (6.3%) had no response (NR). The median time to obtain CR was 32 (7-426) days after treatment with avatrombopag combined with umbilical cord MSCs. The time to reach 20×10^{^}9/L≤ PLT <50×10^{^}9/L in the 2 patients with PR was 52 and 230 days after treatment, respectively. One patient had a severe pulmonary infection and died of cytomegalovirus pneumonia. Overall, our results indicated that combination of avatrombopag with MSCs can promote platelet recovery after transplantation, thereby improving the survival rate of patients and improving the quality of life of patients after transplantation, and providing a new method and strategy for the treatment of thrombocytopenia after allo-HSCT.

Infusion of haploidentical HSCs combined with allogenic MSCs for the treatment of ALL patients

Although haploidentical stem cell transplantation (haplo-HSCT) offers almost all acute lymphoblastic leukaemia (ALL) patients an opportunity for immediate transplantation, it exhibits a higher incidence of graft failure and graft versus host disease (GVHD). Mesenchymal stem cells (MSCs) are characterised by their haematopoiesis-promoting and immunomodulatory capacity. Thus, we designed a combination of haplo-HSCT and MSCs for ALL patients. ALL patients (n = 110) were given haploidentical HSCs combined with allogenic MSCs, and ALL patients without MSC infusion (n = 56) were included as controls. The 100-day cumulative incidences of grade ≥2 acute GVHD (aGVHD) and grade ≥3 aGVHD were 40.00% and 9.09% compared to 42.32% (P = 0.79) and 22.79% (P = 0.03) in patients without MSC infusion, respectively. The 3-year cumulative incidences of chronic GVHD (cGVHD) and extensive cGVHD were 22.27% and 10.27% compared to 32.14% (P = 0.19) and 22.21% (P = 0.04) in patients without MSC infusion, respectively. No significant differences in the 3-year relapse incidence, nonrelapse mortality, leukaemia-free survival or overall survival in groups with and without MSC cotransplantation were observed. Multivariate analysis showed that MSC infusion contributed to a lower risk of developing extensive cGVHD. Our data suggested that haplo-HSCT combined with MSCs may provide an effective and safe treatment for ALL patients.

Combination of Haploidentical Hematopoietic Stem Cell Transplantation with Umbilical Cord-Derived Mesenchymal Stem Cells in Patients with Severe Aplastic Anemia: a Retrospective, Controlled Study

Objective:

We retrospectively compared the outcomes of patients with severe aplastic anemia (SAA) who received haploidentical hematopoietic stem cell transplantation (haplo-HSCT) combined or not combined with umbilical cord-derived mesenchymal stem cells (UC-MSCs).

Materials and Methods:

A total of 101 patients with SAA were enrolled in this study and treated with haplo-HSCT plus UC-MSC infusion (MSC group, n=47) or haplo-HSCT alone (non-MSC group, n=54).

Results:

The median time to neutrophil engraftment in the MSC and non-MSC group was 11 (range: 8-19) and 12 (range: 8-23) days, respectively (p=0.049), with a respective cumulative incidence (CI) of 97.82% and 97.96% (p=0.101). Compared to the non-MSC group, the MSC group had a lower CI of chronic graft-versus-host disease (GVHD) (8.60±0.25% vs. 24.57±0.48%, p=0.048), but similar rates of grades II-IV acute GVHD (23.40±0.39% vs. 24.49±0.39%, p=0.849), grades III-IV acute GVHD (8.51±0.17% vs. 10.20±0.19%, p=0.765), and moderate-severe chronic GVHD (2.38±0.06% vs. 7.45±0.18%, p=0.352) were observed. The estimated 5-year overall survival (OS) rates were 78.3±6.1% and 70.1±6.3% (p=0.292) while the estimated 5-year GVHD-free, failure-free survival (GFFS) rates were 76.6±6.2% and 56.7±6.9% (p=0.045) in the MSC and non-MSC groups, respectively.

Conclusion:

In multivariate analysis, graft failure was the only adverse predictor for OS. Meanwhile, graft failure, grades III-IV acute GVHD, and moderate-severe chronic GVHD could predict worse GFFS. Our results indicated that haplo-HSCT combined with UC-MSCs infusion was an effective and safe option for SAA patients.

A Brief Overview of Global Trends in MSC-Based Cell Therapy

Human mesenchymal stem cells (MSCs), also known as mesenchymal stromal cells or medicinal signaling cells, are important adult stem cells for regenerative medicine, largely due to their regenerative characteristics such as self-renewal, secretion of trophic factors, and the capability of inducing mesenchymal cell lineages. MSCs also possess homing and trophic properties modulating immune system, influencing microenvironment around damaged tissues and enhancing tissue repair, thus offering a broad perspective in cell-based therapies. Therefore, it is not surprising that MSCs have been the broadly used adult stem cells in clinical trials. To gain better insights into the current applications of MSCs in clinical applications, we perform a comprehensive review of reported data of MSCs clinical trials conducted globally. We summarize the biological effects and mechanisms of action of MSCs, elucidating recent clinical trials phases and findings, highlighting therapeutic effects of MSCs in several representative diseases, including neurological, musculoskeletal diseases and most recent Coronavirus infectious disease. Finally, we also highlight the challenges faced by many clinical trials and propose potential solutions to streamline the use of MSCs in routine clinical applications and regenerative medicine.

Mesenchymal Stromal Cells for Enhancing Hematopoietic Engraftment and Treatment of Graft-Versus-Host Disease, Hemorrhages and Acute Respiratory Distress Syndrome

Mesenchymal stromal cells (MSCs) possess profound immunomodulatory and regenerative properties that are of clinical use in numerous clinical indications with unmet medical need. Common sources of MSCs include among others, bone marrow (BM), fat, umbilical cord, and placenta-derived decidua stromal cells (DSCs). We here summarize our more than 20-years of scientific experience in the clinical use of MSCs and DSCs in different clinical settings. BM-MSCs were first explored to enhance the engraftment of autografts in hematopoietic cell transplantation (HCT) and osteogenesis imperfecta around 30 years ago. In 2004, our group reported the first anti-inflammatory use of BM-MSCs in a child with grade IV acute graft-versus-host disease (GvHD). Subsequent studies have shown that MSCs appear to be more effective in acute than chronic GvHD. Today BM-MSC-therapy is registered for acute GvHD in Japan and for GvHD in children in Canada and New Zeeland. MSCs first home to the lung following intravenous injection and exert strong local and systemic immunomodulatory effects on the host immune system. Thus, they were studied for ameliorating the cytokine storm in acute respiratory distress syndrome (ARDS). Both, MSCs and DSCs were used to treat SARS-CoV-2 coronavirus-induced disease 2019 (COVID-19)-induced ARDS. In addition, they were also used for other novel indications, such as pneumomediastinum, colon perforation, and radiculomyelopathy. MSC and DSCs trigger coagulation and were thus explored to stop hemorrhages. DSCs appear to be more effective for acute GvHD, ARDS, and hemorrhages, but randomized studies are needed to prove superiority. Stromal cell infusion is safe, well tolerated, and only gives rise to a slight fever in a limited number of patients, but no major side effects have been reported in multiple safety studies and metaanalysis. In this review we summarize current evidence from in vitro studies, animal models, and importantly our clinical experience, to support stromal cell therapy in multiple clinical indications. This encloses MSC’s effects on the immune system, coagulation, and their safety and efficacy, which are discussed in relation to prominent clinical trials within the field.

Mesenchymal stromal cells plus basiliximab, calcineurin inhibitor as treatment of steroid-resistant acute graft-versus-host disease: a multicenter, randomized, phase 3, open-label trial

Background

Steroid-resistant (SR) acute graft-versus-host disease (aGVHD) lacks standard second-line treatment. Mesenchymal stromal cells (MSCs) have potential efficacy in SR aGVHD. We aimed to assess the efficacy and safety of MSCs combined with basiliximab and calcineurin inhibitor as second-line therapy for SR aGVHD.

Methods

A randomized phase 3 trial involved 203 SR aGVHD patients at nine centers in China (September 2014–March 2019). Participants were randomized at a 1:1 ratio to receive second-line therapy with (n = 101) or without (n = 102) MSCs. The primary endpoint was the overall response (OR) at day 28. Secondary and safety endpoints included durable OR at day 56, failure-free survival, overall survival (OS), chronic GVHD (cGVHD), infection, hematological toxicity and relapse.

Results

Of 203 patients, 198 (97.5%; mean age, 30.1 years; 40.4% women) completed the study. The OR at day 28 was higher in the MSC group than the control group (82.8% [82 patients] vs. 70.7% [70]; odds ratio, 2.00; 95% confidence interval [CI], 1.01–3.94; P = 0.043). The durable OR at day 56 was also higher in the MSC group (78.8% [78 patients] vs. 64.6% [64]; odds ratio, 2.02; 95% CI, 1.08–3.83; P = 0.027). The median failure-free survival was longer in the MSC group compared with control (11.3 months vs. 6.0 months; hazard ratio (HR) 0.68; 95% CI, 0.48–0.95, P = 0.024). The 2-year cumulative incidence of cGVHD was 39.5% (95% CI, 29.3–49.4%) and 62.7% (51.4–72.1%) in the MSC and control groups (HR 0.55, 95% CI, 0.36–0.84; P = 0.005). Within 180 days after study treatments, the most common grade 3 and 4 adverse events were infections (65 [65.7%] in the MSC group vs. 78 [78.8%] in the control group) and hematological toxicity (37 [37.4%] vs. 53 [53.5%]). The 3-year cumulative incidence of tumor relapse was 10.1% (95% CI, 5.2–17.1) and 13.5% (7.5–21.2%) in the MSC and control groups, respectively (HR 0.75, 95% CI, 0.34–1.67, P = 0.610).

Conclusions

MSCs plus second-line treatments increase the efficacy of SR aGVHD, decrease drug toxicity of second-line drugs and cGVHD without increasing relapse, and are well-tolerated. MSCs could be recommended as a second-line treatment option for aGVHD patients.

Trial registration clinicaltrials.gov identifier: NCT02241018. Registration date: September 16, 2014, https://clinicaltrials.gov/ct2/show/NCT02241018.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01240-4.

Current status of clinical trials assessing mesenchymal stem cell therapy for graft versus host disease: a systematic review

Background

Graft-versus-host disease (GVHD) is a common fatal complication of hematopoietic stem cell transplantation (HSCT), where steroids are used as a treatment option. However, there are currently no second-line treatments for patients that develop steroid-resistance (SR). Mesenchymal stem cells (MSCs) have immunomodulatory functions and can exert immunosuppressive effects on the inflammatory microenvironment. A large number of in vitro experiments have confirmed that MSCs can significantly inhibit the proliferation or activation of innate and adaptive immune cells. In a mouse model of GVHD, MSCs improved weight loss and increased survival rate. Therefore, there is great promise for the clinical translation of MSCs for the prevention or treatment of GVHD, and several clinical trials have already been conducted to date.

Main body

In this study, we searched multiple databases and found 79 clinical trials involving the use of MSCs to prevent or treat GVHD and summarized the characteristics of these clinical trials, including study design, phase, status, and locations. We analyzed the results of these clinical trials, including the response and survival rates, to enable researchers to obtain a comprehensive understanding of the field’s progress, challenges, limitations, and future development trends. Additionally, factors that might result in inconsistencies in clinical trial results were discussed.

Conclusion

In this study, we attempted to analyze the clinical trials for MSCs in GVHD, identify the most suitable group of patients for MSC therapy, and provide a new perspective for the design of such trials in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02751-0.

Cellular therapies for the treatment and prevention of SARS-CoV-2 infection

Patients with blood disorders who are immune suppressed are at increased risk for infection with severe acute respiratory syndrome coronavirus 2. Sequelae of infection can include severe respiratory disease and/or prolonged duration of viral shedding. Cellular therapies may protect these vulnerable patients by providing antiviral cellular immunity and/or immune modulation. In this recent review of the field, phase 1/2 trials evaluating adoptive cellular therapies with virus-specific T cells or natural killer cells are described along with trials evaluating the safety, feasibility, and preliminary efficacy of immune modulating cellular therapies including regulatory T cells and mesenchymal stromal cells. In addition, the immunologic basis for these therapies is discussed.

Wharton's jelly-derived stromal cells and their cell therapy applications in allogeneic haematopoietic stem cell transplantation

For decades, mesenchymal stromal cells (MSCs) have been of great interest in the fields of regenerative medicine, tissue engineering and immunomodulation. Their tremendous potential makes it desirable to cryopreserve and bank MSCs to increase their accessibility and availability. Postnatally derived MSCs seem to be of particular interest because they are harvested after delivery without ethical controversy, they have the capacity to expand at a higher rate than adult‐derived MSCs, in which expansion decreases with ageing, and they have demonstrated immunological and haematological supportive properties similar to those of adult‐derived MSCs. In this review, we focus on MSCs obtained from Wharton's jelly (the mucous connective tissue of the umbilical cord between the amniotic epithelium and the umbilical vessels). Wharton's jelly MSCs (WJ‐MSCs) are a good candidate for cellular therapy in haematology, with accumulating data supporting their potential to sustain haematopoietic stem cell engraftment and to modulate alloreactivity such as Graft Versus Host Disease (GVHD). We first present an overview of their in‐vitro properties and the results of preclinical murine models confirming the suitability of WJ‐MSCs for cellular therapy in haematology. Next, we focus on clinical trials and discuss tolerance, efficacy and infusion protocols reported in haematology for GVHD and engraftment.

Allogeneic Stem Cell Transplantation Combined With Transfusion of Mesenchymal Stem Cells in Primary Myelofibrosis: A Multicenter Retrospective Study

Background

Allogeneic stem cell transplantation (allo-SCT) remains the only effective curative therapy for primary myelofibrosis. Utilization and efficacy of allo-SCT are limited by lethal complications, including engraftment failure, and acute (aGVHD) and chronic graft-versus-host disease (cGVHD). Several clinical trials have explored the use of mesenchymal stem cells (MSCs) in allo-SCT to prevent hematopoietic stem cell (HSC) engraftment failure and control GVHD.

Methods

Clinical data of 17 patients with primary myelofibrosis who underwent allo-SCT combined with ex vivo expanded MSC transfusion in four centers from February 2011 to December 2018 were retrospectively analyzed.

Results

All patients received myeloablative conditioning regimen. The median number of transplanted nucleated cells (NCs) per kilogram body weight was 11.18 × 10⁸ (range: 2.63–16.75 × 10⁸), and the median number of CD34⁺ cells was 4.72 × 10⁶ (range: 1.32–8.4 × 10⁶). MSCs were transfused on the day of transplant or on day 7 after transplant. The median MSC infusion number was 6.5 × 10⁶ (range: 0.011–65 × 10⁶). None of the patients experienced primary or secondary graft failure in the study. The median time to neutrophil engraftment was 13 days (range: 11–22 days), and the median time to platelet engraftment was 21 days (range: 12–184 days). The median follow-up time was 40.3 months (range: 1.8–127.8 months). The estimated relapse-free survival (RFS) at 5 years was 79.1%, and overall survival (OS) at 5 years was 64.7%. Analysis showed that the cumulative incidence of aGVHD grade II to IV was 36% (95% CI: 8%–55%) and that of grade III to IV was 26% (95% CI: 0%–45%) at day 100. The cumulative incidence of overall cGVHD at 2 years for the entire study population was 63% (95% CI: 26%–81%). The cumulative incidence of moderate to severe cGVHD at 2 years was 17% (95% CI: 0%–42%). Seven patients died during the study, with 5 patients succumbing from non‐relapse causes and 2 from disease relapse.

Conclusion

The findings of the study indicate that allo-SCT combined with MSC transfusion may represent an effective treatment option for primary myelofibrosis.

Efficacy and safety of mesenchymal stem cells treatment for multidrug-resistant graft-versus-host disease after haploidentical allogeneic hematopoietic stem cell transplantation

PURPOSE

Graft-versus-host disease (GVHD) is an important complication after human leukocyte antigen (HLA) haploidentical donor (HID) hematopoietic stem cell transplantation (HSCT), which may lead to poor prognosis. Our study intends to identify the efficacy and safety of mesenchymal stem cells (MSCs) for multidrug-resistant (MDR)-GVHD after HID HSCT.

METHODS

MDR-GVHD was referring to GVHD remaining no response to at least two types of therapy, and hUCB-MSCs were given at the dose of (1.0-2.0) × 106/kg once a week.

RESULTS

A total of 21 patients were enrolled in this retrospective study (acute GVHD (aGVHD): n = 14, chronic GVHD (cGVHD): n = 7). The median dose of MSCs was 1.2 × 106 cells/kg (range, 0.8-1.8 × 106) cells/kg, and the median numbers of infusion were 2 (range, 1-7) and 3 (range, 2-12) for MDR-aGVHD and MDR-cGVHD patients, respectively. In MDR-aGVHD patients, the overall response rate (ORR) was 57.1%, including 50.0% complete response (CR) and 7.1% partial response (PR), and the median time to response was 49.5 days (range, 16-118) days. The 2-year probability of overall survival after MSCs was 64.3%. Five patients (35.7%) developed infections after MSCs, and no obvious hematologic toxicities were observed. Five MDR-aGVHD patients died after MSCs treatments because of GVHD progression (n = 1), severe infection (bacterial central nervous system infection: n = 1; fungal pneumonia: n = 2), and poor graft function (n = 1). In MDR-cGVHD patients, three patients (42.9%) achieved PR after MSCs and the median time to response was 56 days (22-84) days. The ORRs for moderate and severe cGVHD were 50.0% and 33.3%, respectively. Four MDR-cGVHD patients died after MSCs treatments because of GVHD progression (n = 2), severe fungal pneumonia (n = 1), and relapse (n = 1).

CONCLUSION

MSCs treatment may be safe and effective for MDR-GVHD after HID HSCT.

Targeted therapy for advanced anaplastic lymphoma kinase (<I>ALK</I>)-rearranged non-small cell lung cancer

BACKGROUND

Targeted therapies directed at specific driver oncogenes have improved outcomes for individuals with advanced non-small cell lung cancer (NSCLC). Approximately 5% of lung adenocarcinomas, the most common histologic subtype of NSCLC, harbour rearrangements in the anaplastic lymphoma kinase (ALK) gene leading to constitutive activity of the ALK kinase. Crizotinib was the first tyrosine kinase inhibitor (TKI) demonstrated to be effective in advanced NSCLC. Next-generation ALK TKIs have since been developed including ceritinib, alectinib, brigatinib, ensartinib, and lorlatinib, and have been compared with crizotinib or chemotherapy in randomised controlled trials (RCTs). These ALK-targeted therapies are currently used in clinical practice and are endorsed in multiple clinical oncology guidelines.

OBJECTIVES

To evaluate the safety and efficacy of ALK inhibitors given as monotherapy to treat advanced ALK-rearranged NSCLC.

SEARCH METHODS

We conducted electronic searches in the Cochrane Lung Cancer Group Specialised Register, Cochrane Central Register of Controlled Trials, MEDLINE, and Embase. We also searched conference proceedings from the American Society for Clinical Oncology (ASCO), European Society of Medical Oncology (ESMO), and International Association for the Study of Lung Cancer (IASLC) World Conference on Lung Cancer, as well as the reference lists of retrieved articles. All searches were conducted from 2007 until 7 January 2021.

SELECTION CRITERIA

We included RCTs comparing ALK inhibitors with cytotoxic chemotherapy or another ALK inhibitor in individuals with incurable locally advanced or metastatic pathologically confirmed ALK-rearranged NSCLC.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for eligibility, extracted study characteristics and outcome data, and assessed risk of bias using the Cochrane risk of bias tool for each included study. We assessed the certainty of evidence using GRADE. Primary outcomes were progression-free survival (PFS) and adverse events (AE); secondary outcomes were overall survival (OS), OS at one year, overall response rate (ORR) by RECIST (Response Evaluation Criteria in Solid Tumours) criteria, and health-related quality of life (HRQoL). We performed a meta-analysis for all outcomes, where appropriate, using the fixed-effect model. We reported hazard ratios (HR) for PFS, OS, and a composite HRQoL of life outcome (time to deterioration), and risk ratios (RR) for AE, ORR, and one-year OS. We presented 95% confidence intervals (95% CIs) and used the I² statistic to investigate heterogeneity. We planned comparisons of 'ALK inhibitor versus chemotherapy' and 'next-generation ALK inhibitor versus crizotinib' with subgroup analysis by type of ALK inhibitor, line of treatment, and baseline central nervous system involvement.

MAIN RESULTS

Eleven studies (2874 participants) met our inclusion criteria: six studies compared an ALK inhibitor (crizotinib, ceritinib, and alectinib) to chemotherapy, and five studies compared a next-generation ALK inhibitor (alectinib, brigatinib, and lorlatinib) to crizotinib. We assessed the evidence for most outcomes as of moderate to high certainty. Most studies were at low risk for selection, attrition, and reporting bias; however, no RCTs were blinded, resulting in a high risk of performance and detection bias for outcomes reliant on subjective measurement. ALK inhibitor versus chemotherapy Treatment with ALK inhibitors resulted in a large increase in PFS compared to chemotherapy (HR 0.45, 95% CI 0.40 to 0.52, 6 RCTs, 1611 participants, high-certainty evidence). This was found regardless of line of treatment. ALK inhibitors may result in no difference in overall AE rate when compared to chemotherapy (RR 1.01, 95% CI 1.00 to 1.03, 5 RCTs, 1404 participants, low-certainty evidence). ALK inhibitors slightly improved OS (HR 0.84, 95% CI 0.72 to 0.97, 6 RCTs, 1611 participants, high-certainty evidence), despite most included studies having a significant number of participants crossing over from chemotherapy to receive an ALK inhibitor after the study period. ALK inhibitors likely increase ORR (RR 2.43, 95% CI 2.16 to 2.75, 6 RCTs, 1611 participants, moderate-certainty evidence) including in measurable baseline brain metastases (RR 4.88, 95% CI 2.18 to 10.95, 3 RCTs, 108 participants) when compared to chemotherapy. ALK inhibitors result in a large increase in the HRQoL measure, time to deterioration (HR 0.52, 95% CI 0.44 to 0.60, 5 RCTs, 1504 participants, high-certainty evidence) when compared to chemotherapy. Next-generation ALK inhibitor versus crizotinib Next-generation ALK inhibitors resulted in a large increase in PFS (HR 0.39, 95% CI 0.33 to 0.46, 5 RCTs, 1263 participants, high-certainty evidence), particularly in participants with baseline brain metastases. Next-generation ALK inhibitors likely result in no difference in overall AE (RR 1.00, 95% CI 0.98 to 1.01, 5 RCTs, 1263 participants, moderate-certainty evidence) when compared to crizotinib. Next-generation ALK inhibitors likely increase OS (HR 0.71, 95% CI 0.56 to 0.90, 5 RCTs, 1263 participants, moderate-certainty evidence) and slightly increase ORR (RR 1.18, 95% CI 1.10 to 1.25, 5 RCTs, 1229 participants, moderate-certainty evidence) including a response in measurable brain metastases (RR 2.45, 95% CI 1.7 to 3.54, 4 RCTs, 138 participants) when compared to crizotinib. Studies comparing ALK inhibitors were conducted exclusively or partly in the first-line setting.

AUTHORS' CONCLUSIONS

Next-generation ALK inhibitors including alectinib, brigatinib, and lorlatinib are the preferred first systemic treatment for individuals with advanced ALK-rearranged NSCLC. Further trials are ongoing including investigation of first-line ensartinib. Next-generation inhibitors have not been compared to each other, and it is unknown which should be used first and what subsequent treatment sequence is optimal.

Management of Chronic Graft-vs.-Host Disease in Children and Adolescents With ALL: Present Status and Model for a Personalised Management Plan

Herein we review current practice regarding the management of chronic graft-vs.-host disease (cGvHD) in paediatric patients after allogeneic haematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukaemia (ALL). Topics covered include: (i) the epidemiology of cGvHD; (ii) an overview of advances in our understanding cGvHD pathogenesis; (iii) current knowledge regarding risk factors for cGvHD and prevention strategies complemented by biomarkers; (iii) the paediatric aspects of the 2014 National Institutes for Health-defined diagnosis and grading of cGvHD; and (iv) current options for cGvHD treatment. We cover topical therapy and newly approved tyrosine kinase inhibitors, emphasising the use of immunomodulatory approaches in the context of the delicate counterbalance between immunosuppression and immune reconstitution as well as risks of relapse and infectious complications. We examine real-world approaches of response assessment and tapering schedules of treatment. Furthermore, we report on the optimal timepoints for therapeutic interventions and changes in relation to immune reconstitution and risk of relapse/infection. Additionally, we review the different options for anti-infectious prophylaxis. Finally, we put forth a theory of a holistic view of paediatric cGvHD and its associated manifestations and propose a checklist for individualised risk evaluation with aggregated considerations including site-specific cGvHD evaluation with attention to each individual's GvHD history, previous medical history, comorbidities, and personal tolerance and psychosocial circumstances. To complement this checklist, we present a treatment algorithm using representative patients to inform the personalised management plans for patients with cGvHD after HSCT for ALL who are at high risk of relapse.

Fractional laser-assisted administration of human umbilical cord mesenchymal stem cells to reduce hypertrophic scars in rabbit ears

BACKGROUND

The formation of hypertrophic scar is due to the abnormal accumulation and remodeling of the extracellular matrix, especially collagen tissue. Our research was designed to investigate the treatment effect of different administrations of human umbilical cord-derived stem cells and to hypertrophic scars on rabbit ears.

METHODS

Thirty New Zealand female white rabbits were treated as hypertrophic scar models. PBS was injected into the scars on the right ear of each group as control, while human umbilical cord-derived stem cells or condition medium of human umbilical cord-derived stem cells were administrated into the left ear through subcutaneous injection or fractional laser-assisted administration. Gross examination, scar elevation index (SEI) calculation and sampling were executed 5 weeks after administration. Then H&E and Masson staining analysis and the expression levels detections of α-SMA, Collagen I, TGF-β1, IL-1β, and IL-6 were performed.

RESULTS

Our results demonstrated that the severity of hyperplasia was lower than the model group after stem cells and conditioned medium treatment. H&E and Masson staining results showed that the inflammation in scars was greatly alleviated and the degree of fibrosis was reduced after treatment. There was no significant difference in the therapeutic effect between subcutaneous injection or fractional laser-assisted administration. Both stem cells and conditioned medium can down-regulate SEI and factors expression levels in all groups. However, compared with the stem cells, the therapeutic effects of the conditioned medium were lower.

CONCLUSIONS

The results confirmed that stem cells had an available treatment effect on hypertrophic scars of rabbit ears. In addition to the paracrine pathway, stem cells may have other ways to treat hypertrophic scars. Fractional laser-assisted administration may become a potential administration of stem cell clinical application in the future.

Haploidentical Stem Cell Transplantation for Acute Myeloid Leukemia: Current Therapies, Challenges and Future Prospective

Haploidentical stem cell transplantation (haplo-SCT), an alternative donor source, offers a curative therapy for patients with acute myeloid leukemia (AML) who are transplant candidates. Advances in transplantation techniques, such as donor selection, conditioning regimen modification, and graft-versus-host disease prophylaxis, have successfully improved the outcomes of AML patients receiving haplo-SCT and extended the haploidentical transplant indictions for AML. Presently, treating de novo AML, secondary AML, therapy-related AML and refractory and relapsed AML with haplo-SCT can achieve comparable outcomes to those of human leukocyte antigen (HLA)-matched sibling donor transplantation (MSDT), unrelated donor transplantation or umbilical cord blood transplantation. For some subgroups of AML subjects, such as patients with positive pretransplantation minimal/measurable residual disease, recent studies suggest that haplo-SCT might be superior to MSDT in decreasing relapse and improving survival. Unfortunately, for patients with AML after haplo-SCT, relapse and infections remain the causes of death that restrict further improvement in clinical outcomes. In this review, we discuss the recent advances and challenges in haplo-SCT for AML treatment, mainly focusing on unmanipulated haplo-SCT protocols. We provide an outlook on future prospects and suggest that relapse prophylaxis, intervention, and treatment, as well as infection prevention and therapy, are areas of active research in AML patients who receive haploidentical allografts.

Recent Metabolic Advances for Preventing and Treating Acute and Chronic Graft Versus Host Disease

The therapeutic efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) is limited by the development of graft-versus-host disease (GVHD). In GVHD, rigorous pre-conditioning regimen resets the immune landscape and inflammatory milieu causing immune dysregulation, characterized by an expansion of alloreactive cells and a reduction in immune regulatory cells. In acute GVHD (aGVHD), the release of damage- and pathogen- associated molecular patterns from damaged tissue caused by the conditioning regimen sets the stage for T cell priming, activation and expansion further exacerbating tissue injury and organ damage, particularly in the gastrointestinal tract. Studies have shown that donor T cells utilize multiple energetic and biosynthetic pathways to mediate GVHD that can be distinct from the pathways used by regulatory T cells for their suppressive function. In chronic GVHD (cGVHD), donor T cells may differentiate into IL-21 producing T follicular helper cells or tissue resident T helper cells that cooperate with germinal center B cells or memory B cells, respectively, to produce allo- and auto-reactive antibodies with subsequent tissue fibrosis. Alternatively, donor T cells can become IFN- γ/IL-17 cytokine expressing T cells that mediate sclerodermatous skin injury. Patients refractory to the first line standard regimens for GVHD treatment have a poor prognosis indicating an urgent need for new therapies to restore the balance between effector and regulatory immune cells while preserving the beneficial graft-versus-tumor effect. Emerging data points toward a role for metabolism in regulating these allo- and auto-immune responses. Here, we will discuss the preclinical and clinical data available on the distinct metabolic demands of acute and chronic GVHD and recent efforts in identifying therapeutic targets using metabolomics. Another dimension of this review will examine the changing microbiome after allo-HSCT and the role of microbial metabolites such as short chain fatty acids and long chain fatty acids on regulating immune responses. Lastly, we will examine the metabolic implications of coinhibitory pathway blockade and cellular therapies in allo-HSCT. In conclusion, greater understanding of metabolic pathways involved in immune cell dysregulation during allo-HSCT may pave the way to provide novel therapies to prevent and treat GVHD.

Umbilical cord-derived mesenchymal stem cells promote myeloid-derived suppressor cell enrichment by secreting CXCL1 to prevent graft-versus-host disease after hematopoietic stem cell transplantation

BACKGROUND AIMS

Human mesenchymal stem cells (MSCs) from various tissues have emerged as attractive candidates for the prevention and treatment of graft-versus-host disease (GVHD). However, the molecular machinery that defines and channels the behavior of these cells remains poorly understood.

METHODS

In this study, the authors compared the efficacy of four tissue-derived MSC types in controlling GVHD in a murine model and investigated their immunomodulatory effects.

RESULTS

Human umbilical cord-derived mesenchymal stem cells (hUCMSCs) effectively decreased the incidence and severity of GVHD, which was mediated by the enrichment of myeloid-derived suppressor cells in GVHD target tissues. RNA sequencing results showed that hUCMSCs highly expressed CXCL1.

CONCLUSIONS

These results suggest a novel prophylactic application of hUCMSCs for controlling GVHD after allogeneic hematopoietic stem cell transplantation.

COVID-19 and the role of stem cells

There is currently an ongoing coronavirus respiratory disease (COVID-19) pandemic that is caused by SARS-CoV-2 virus, which emerged out of Wuhan, China. In severe cases, the disease can progress to respiratory distress, hypoxia, and multi-organ failure, all of which are associated with high mortality. Mesenchymal stem cells (MSCs) possess potent and broad-ranging immunomodulatory activities. MSCs have demonstrated their impressive ability to inhibit lung damage, reduce inflammation, attenuate the immune response, and aid with alveolar fluid clearance. Studies that investigated the use of MSCs and exosome cells derived from MSCs in treating COVD-19 patients have encouraging results. The conclusion of the results of four clinical studies, as presented in this review article, is reduced patient mortality in more than half of the subjects who were administered MSCs or exosomes derived from MSCs, intravenously, positioning these cells as a possible therapeutic solution for COVID-19. While the studies do have limitations, they do provide a stepping stone based on different approaches in the search for treatment to save patients.

Preclinical efficacy and clinical safety of clinical-grade nebulized allogenic adipose mesenchymal stromal cells-derived extracellular vesicles

Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) turn out to be a promising source of cell-free therapy. Here, we investigated the biodistribution and effect of nebulized human adipose-derived MSC-EVs (haMSC-EVs) in the preclinical lung injury model and explored the safety of nebulized haMSC-EVs in healthy volunteers. DiR-labelled haMSC-EVs were used to explore the distribution of nebulized haMSC-EVs in the murine model. Pseudomonas aeruginosa-induced murine lung injury model was established, and survival rate, as well as WBC counts, histology, IL-6, TNF-α and IL-10 levels in bronchoalveolar lavage fluid (BALF) were measured to explore the optimal therapeutic dose of haMSC-EVs through the nebulized route. Twenty-four healthy volunteers were involved and received the haMSC-EVs once, ranging from 2 × 108 particles to 16 × 108 particles (MEXVT study, NCT04313647). Nebulizing haMSC-EVs improved survival rate to 80% at 96 h in P. aeruginosa-induced murine lung injury model by decreasing lung inflammation and histological severity. All volunteers tolerated the haMSC-EVs nebulization well, and no serious adverse events were observed from starting nebulization to the 7th day after nebulization. These findings suggest that nebulized haMSC-EVs could be a promising therapeutic strategy, offering preliminary evidence to promote the future clinical applications of nebulized haMSC-EVs in lung injury diseases.

Case Report: Human Umbilical Cord Mesenchymal Stem Cells as a Therapeutic Intervention for a Critically Ill COVID-19 Patient

Here we report a critically ill patient who was cured of SARS-CoV-2 infection in Changsha, China. A 66-year-old Chinese woman, with no significant past medical history, developed severe pneumonia-like symptoms and later diagnosed as severe COVID-19 pneumonia. Within 2 months of hospitalization, the patient deteriorated to ARDS including pulmonary edema and SIRS with septic shock. When treatment schemes such as antibiotics plus corticosteroids showed diminished therapeutic value, hUCMSC therapy was compassionately prescribed under the patient's consent of participation. After treatment, there was significant improvement in disease inflammation-related indicators such as IL-4, IL-6, and IL-10. Eventually, it confirmed the therapeutic value that hUCMSCs could dampen the cytokine storm in the critically ill COVID-19 patient and modulated the NK cells. In the continued hUCMSC treatment, gratifying results were achieved in the follow-up of the patient. The data we acquired anticipate a significant therapeutic value of MSC treatment in severe and critically ill patients with COVID-19, while further studies are needed.

High-dose Chemotherapy Combined with Autologous Hematopoietic Stem Cell Transplantation as Frontline Therapy for Intermediate/High-risk Diffuse Large B Cell Lymphoma

The role of autologous hematopoietic stem cell transplantation (auto-HSCT) following high-dose chemotherapy has been validated and accepted as a standard treatment for patients with relapsed diffuse large B-cell lymphoma (DLBCL). However, its clinical efficacy as frontline therapy remains to be elucidated. This study aimed to examine the feasibility of frontline auto-HSCT for newly diagnosed intermediate/high-risk DLBCL patients. We retrospectively reviewed the data of 223 patients treated with frontline auto-HSCT or chemotherapy alone (year 2008-2014) from four hospitals. The median follow-up time was 29.4 months. Between the two treatment arms among the intermediate/high-risk DLBCL patients, the 3-year overall survival (OS) and progression-free survival (PFS) rates of patients given frontline auto-HSCT were 87.6% and 81.9%, respectively, and the chemotherapy-alone group showed 3-year OS and PFS rates of 64.9% and 59.59%, respectively. Compared with the chemotherapy-alone group, the frontline auto-HSCT could eliminate the adverse impact of non-germinal center B-cell (GCB) type. In addition, in the frontline auto-HSCT group, patients who achieved complete response (CR) at auto-HSCT had a longer survival time than those who did not achieve CR. Our results suggested that frontline auto-HSCT could improve the prognosis of intermediate/high-risk DLBCL patients.