Mesenchymal stromal cells as prophylaxis for graft-versus-host disease in haplo-identical hematopoietic stem cell transplantation recipients with severe aplastic anemia?-a systematic review and meta-analysis

[Clinical analysis of 76 patients with severe aplastic anemia treated with haploid hematopoietic stem cell transplantation]

Objective: The purpose of this study is to determine the efficacy of haploidentical donor hematopoietic stem cell transplantation in the treatment of severe aplastic anemia. Methods: The clinical data of 76 patients with severe aplastic anemia (SAA) patients who underwent haplo-HSCT from December 2014 to October 2020 were selectively analyzed. There were 50 males and 26 females with a median age of 16 (3-52) years old. There were 49 SAA-Ⅰ patients, 18 SAA-Ⅱ patients, and 9 patients with hepatitis-associated aplastic anemia. There were 15 cases of bone marrow put together with peripheral blood stem cell transplantation and 61 cases of peripheral blood stem-cell transplantation. Conditioning regimens were Cyclophosphamide (CY) + Fludarabine (Flu) + ATG for 46 patients and Busulfan (Bu) + CY+Flu+ATG for 30 patients. Results: Three patients died during the myelosuppressive phase following transplantation, and 73 patients had a median time of neutrophil engraftment of 12 (9-21) days; in addition to 3 patients who died early, 8 patients did not obtain platelet reconstruction after transplantation, and 65 patients had platelet engraftment with a medium time of 14 (9-90) d. The incidence of primary graft failure was 10.9% and the incidence of secondary graft failure was 5.5%. The incidence of Ⅱ-Ⅳ acute graft-versus-host disease (aGVHD) was 38.4%, the incidence of Ⅲ-Ⅳ aGVHD was 16.4%, the incidence of chronic graft anti-host disease (cGVHD) was 35.8%, and the incidence of extensive cGVHD was 22.4%. The medium follow-up time was 19.5 (1-75) months, the prospective overall survival (OS) for 2 years was (78.6±5.0) %, the failure-free survival (FFS) was (75.9±5.1) %, and the transplant-related mortality was (20.2±4.9) %. Multi-factor analysis revealed that the patient older than 35 years old, Ⅲ/Ⅳ aGVHD, HCT-CI≥3, the pre-transplant ferritin ≥1 500 μg/L, the number of neutrophils >1×10(9)/L at the time of onset were risk factors affecting OS (P=0.008, 0.008, 0.014, 0.004, 0.027) . Patients with graft failure had lower OS and FFS than other patients (P<0.001) . Conclusion: Haplo-HSCT is an effective method for treating SAA in children, adolescents, and young patients, and the occurrence of severe aGVHD and severe infection, as well as graft failure, are the main causes of survival rate. The prevention and treatment of severe aGVHD and infection are essential to improve efficacy.

Safety and Efficacy of Co-transplantation of Hematopoietic Stem Cells Combined With Human Umbilical Cord-Derived Mesenchymal Stem Cells in Children With Severe Aplastic Anemia: A Single-Center Experience

OBJECTIVES

The mostimportant problems thatlimitthe effectiveness of allogeneic hematopoietic stem cell transplantation in patients with severe aplastic anemia are graft failure and graft-versus-host disease. Mesenchymal stem cells can support normal hematopoiesis and prevent graft-versus-host disease. We aimed to analyze the effects of combined transplant of human umbilical cord-derived mesenchymal stem cells and matched donor allogeneic hematopoietic stem cells in children with severe aplastic anemia.

MATERIALS AND METHODS

We retrospectively examined 15 pediatric patients with severe aplastic anemia who received fludarabine-based reduced intensity conditioning regimen and intravenously infused human umbilical cord-derived mesenchymal stem cells at a dose of 1 × 106/kg recipient body weight within 12 to 18 hours before hematopoietic stem cells infusion. We evaluated the engraftment rate, the frequency and severity of graft-versus-host disease, and the overall survival rate.

RESULTS

No patients had adverse events related to intravenously human umbilical cord-derived mesenchymal stem cells infusion. All patients achieved successful engraftment and sustained donor chimerism. The median time for neutrophil and platelet engraftment was 14 and 25 days,respectively. The frequency was 20% for grade III/IV acute graftversus- host disease and 15.3% for chronic graftversus-host disease. Patients were followed-up for a median of 33 months (range, 2-89 months). The 5-year overall survival rate was 80%.

CONCLUSIONS

Combined transplant of matched donor hematopoietic stem cells with human umbilical cord-derived mesenchymal stem cells is safe in pediatric patients with severe aplastic anemia. The achievement of engraftment in all of our patients and the acceptable frequency of acute and chronic graft-versus-host disease and survival rate are encouraging.

Marrow changes and reduced proliferative capacity of mesenchymal stromal cells from patients with "no-option" critical limb ischemia; observations on feasibility of the autologous approach from a clinical trial

BACKGROUND AIMS

Approximately 1 in 3 patients with critical limb ischemia (CLI) are not suitable for surgical or endovascular revascularization. Those "no-option" patients are at high risk of amputation and death. Autologous bone marrow mesenchymal stromal cells (MSCs) may provide a limb salvage option. In this study, bone marrow characteristics and expansion potentials of CLI-derived MSCs produced during a phase 1b clinical trial were compared with young healthy donor MSCs to determine the feasibility of an autologous approach. Cells were produced under Good Manufacturing Practice conditions and underwent appropriate release testing.

METHODS

Five bone marrow aspirates derived from patients with CLI were compared with six young healthy donor marrows in terms of number of colony-forming units-fibroblast (CFUF) and mononuclear cells. The mean population doubling times and final cell yields were used to evaluate expansion potential. The effect of increasing the volume of marrow on the CFUF count and final cell yield was evaluated by comparing 5 CLI-derived MSCs batches produced from a targeted 30 mL of marrow aspirate to five batches produced from a targeted 100 mL of marrow.

RESULTS

CLI-derived marrow aspirate showed significantly lower numbers of mononuclear cells with no difference in the number of CFUFs when compared with healthy donors' marrow aspirate. CLI-derived MSCs showed a significantly longer population doubling time and reduced final cell yield compared with young healthy donors' MSCs. The poor growth kinetics of CLI MSCs were not mitigated by increasing the bone marrow aspirate from 30 to 100 mL.

CONCLUSIONS

In addition to the previously reported karyotype abnormalities in MSCs isolated from patients with CLI, but not in cells from healthy donors, the feasibility of autologous transplantation of bone marrow MSCs for patients with no-option CLI is further limited by the increased expansion time and the reduced cell yield.

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.

How mesenchymal stem cell cotransplantation with hematopoietic stem cells can improve engraftment in animal models

BACKGROUND

Bone marrow transplantation (BMT) can be applied to both hematopoietic and nonhematopoietic diseases; nonetheless, it still comes with a number of challenges and limitations that contribute to treatment failure. Bearing this in mind, a possible way to increase the success rate of BMT would be cotransplantation of mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) to improve the bone marrow niche and secrete molecules that enhance the hematopoietic engraftment.

AIM

To analyze HSC and MSC characteristics and their interactions through cotransplantation in murine models.

METHODS

We searched for original articles indexed in PubMed and Scopus during the last decade that used HSC and MSC cotransplantation and in vivo BMT in animal models while evaluating cell engraftment. We excluded in vitro studies or studies that involved graft versus host disease or other hematological diseases and publications in languages other than English. In PubMed, we initially identified 555 articles and after selection, only 12 were chosen. In Scopus, 2010 were identified, and six were left after the screening and eligibility process.

RESULTS

Of the 2565 articles found in the databases, only 18 original studies met the eligibility criteria. HSC distribution by source showed similar ratios, with human umbilical cord blood or animal bone marrow being administered mainly with a dose of 1 × 10⁷ cells by intravenous or intrabone routes. However, MSCs had a high prevalence of human donors with a variety of sources (umbilical cord blood, bone marrow, tonsil, adipose tissue or fetal lung), using a lower dose, mainly 10⁶ cells and ranging 10⁴ to 1.5 × 10⁷ cells, utilizing the same routes. MSCs were characterized prior to administration in almost every experiment. The recipient used was mostly immunodeficient mice submitted to low-dose irradiation or chemotherapy. The main technique of engraftment for HSC and MSC cotransplantation evaluation was chimerism, followed by hematopoietic reconstitution and survival analysis. Besides the engraftment, homing and cellularity were also evaluated in some studies.

CONCLUSION

The preclinical findings validate the potential of MSCs to enable HSC engraftment in vivo in both xenogeneic and allogeneic hematopoietic cell transplantation animal models, in the absence of toxicity.

Recent Advancements in Poor Graft Function Following Hematopoietic Stem Cell Transplantation

Poor graft function (PGF) is a life-threatening complication that occurs after transplantation and has a poor prognosis. With the rapid development of haploidentical hematopoietic stem cell transplantation, the pathogenesis of PGF has become an important issue. Studies of the pathogenesis of PGF have resulted in some success in CD34⁺-selected stem cell boosting. Mesenchymal stem cells, N-acetyl-l-cysteine, and eltrombopag have also been investigated as therapeutic strategies for PGF. However, predicting and preventing PGF remains challenging. Here, we propose that the seed, soil, and insect theories of aplastic anemia also apply to PGF; CD34⁺ cells are compared to seeds; the bone marrow microenvironment to soil; and virus infection, iron overload, and donor-specific anti-human leukocyte antigen antibodies to insects. From this perspective, we summarize the available information on the common risk factors of PGF, focusing on its potential mechanism. In addition, the safety and efficacy of new strategies for treating PGF are discussed to provide a foundation for preventing and treating this complex clinical problem.

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.

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.