Functional mesenchymal stem cells remain present in bone marrow microenvironment of patients with leukemia post-allogeneic hematopoietic stem cell transplant

Platelet-Derived Mitochondria Attenuate 5-FU-Induced Injury to Bone-Associated Mesenchymal Stem Cells

Background

Myelosuppression is a common condition during chemotherapy. Bone-associated mesenchymal stem cells (BA-MSCs) play an essential role in the composition of the hematopoietic microenvironment and support hematopoietic activity. However, chemotherapy-induced damage to BA-MSCs is rarely studied. Recent studies have shown that platelets promote the wound-healing capability of MSCs by mitochondrial transfer. Therefore, this study is aimed at investigating the chemotherapy-induced damage to BA-MSCs and the therapeutic effect of platelet-derived mitochondria. Material/Methods. We established in vivo and in vitro BA-MSC chemotherapy injury models using the chemotherapy agent 5-fluorouracil (5-FU). Changes in the mitochondrial dynamics were detected by transmission electron microscopy, and the expression of mitochondrial fusion and fission genes was analyzed by qRT-PCR. In addition, mitochondrial functions were also explored by flow cytometry and luminometer. Platelet-derived mitochondria were incubated with 5-FU-damaged BA-MSCs to repair the injury, and BA-MSC functional changes were examined to assess the therapy efficacy. The mechanism of treatment was explored by studying the expression of mitochondrial fission and fusion genes and hematopoietic regulatory factor genes in BA-MSCs.

Results

Stimulation with 5-FU increased the apoptosis and suppressed cell cycle progression of BA-MSCs both in vivo and in vitro. In addition, 5-FU chemotherapy inhibited the hematopoietic regulatory ability and disrupted the mitochondrial dynamics and functions of BA-MSCs. The mitochondrial membrane potential and ATP content of 5-FU-injured BA-MSCs were decreased. Interestingly, when platelet-derived mitochondria were transferred to BA-MSCs, the 5-FU-induced apoptosis was alleviated, and the hematopoietic regulatory ability of 5-FU-injured BA-MSCs was effectively improved by upregulating the expression of mitochondrial fusion genes and hematopoietic regulatory factor genes.

Conclusion

BA-MSCs were severely damaged by 5-FU chemotherapy both in vivo and in vitro. Meanwhile, platelet-derived mitochondria could attenuate the 5-FU-induced injury to BA-MSCs, which provides future research directions for exploring the treatment strategies for chemotherapy-injured BA-MSCs and establishes a research basis for related fields.

Infusion of haploidentical hematopoietic stem cells combined with mesenchymal stem cells for treatment of severe aplastic anemia in adult patients yields curative effects

BACKGROUND AIMS

Despite the great advances in immunosuppressive therapy for severe aplastic anemia (SAA), most patients are not completely cured. Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) has been recommended as an alternative treatment in adult SAA patients. However, haplo-HSCT presents a higher incidence of graft failure and graft-versus-host disease (GVHD). The authors designed a combination of haplo-HSCT and umbilical cord-derived mesenchymal stem cells (UC-MSCs) for treatment of SAA in adult patients and evaluated its effects.

METHODS

Adult patients (≥18 years) with SAA (N = 25) were given HLA-haploidentical hematopoietic stem cells (HSCs) combined with UC-MSCs after a conditioning regimen consisting of busulfan, cyclophosphamide, fludarabine and anti-thymocyte globulin and intensive GVHD prophylaxis, including cyclosporine, basiliximab, mycophenolate mofetil and short-term methotrexate. Additionally, the effects of the protocol in adult SSA patients were compared with those observed in juvenile SAA patients (N = 75).

RESULTS

All patients achieved myeloid engraftment after haplo-HSCT at a median of 16.12 days (range, 11-26). The median time of platelet engraftment was 28.30 days (range, 13-143). The cumulative incidence of grade II acute GVHD (aGVHD) at day +100 was 32.00 ± 0.91%. No one had grade III-IV aGVHD at day +100. The cumulative incidence of total chronic GVHD was 28.00 ± 0.85%. The overall survival was 71.78 ± 9.05% at a median follow-up of 42.08 months (range, 2.67-104). Promisingly, the protocol yielded a similar curative effect in both young and adult SAA patients.

CONCLUSIONS

The authors' data suggest that co-transplantation of HLA-haploidentical HSCs and UC-MSCs may provide an effective and safe treatment for adult SAA.

Enhanced regeneration of bone defects using sintered porous Ti6Al4V scaffolds incorporated with mesenchymal stem cells and platelet-rich plasma

A new highly controlled powder sintering technique was used for the fabrication of a porous Ti6Al4V scaffold. The platelet-rich plasma (PRP) was prepared using whole blood. The PRP was used as a cell carrier to inject bone marrow mesenchymal stem cells (MSC) into the pores of the Ti6Al4V scaffold in the presence of calcium chloride and thrombin, and then the composite construct of porous Ti6Al4V loaded with PRP gel and MSC was obtained. The bare Ti6Al4V scaffold and the Ti6Al4V scaffold loaded with MSC were used as controls. The characteristics and mechanical properties of the scaffold, and the biological properties of the constructs were evaluated by a series of in vitro and in vivo experiments. The results show that the sintered porous Ti6Al4V has good biocompatibility, and high porosity and large pore size, which can provide sufficient space and sufficient mechanical support for the growth of cells and bones without an obvious stress shielding effect. However, Ti6Al4V/MSC/PRP showed a significantly higher cell proliferation rate, faster bone growth speed, more bone ingrowth, and higher interfacial strength. Therefore, the porous Ti6Al4V scaffolds incorporated with MSC and PRP may be more effective at enhancing bone regeneration, and is expected to be used for bone defect repair.

Hematopoietic Stem Cell Niche During Homeostasis, Malignancy, and Bone Marrow Transplantation

Self-renewal and multidirectional differentiation of hematopoietic stem cells (HSCs) are strictly regulated by numerous cellular components and cytokines in the bone marrow (BM) microenvironment. Several cell types that regulate HSC niche have been identified, including both non-hematopoietic cells and HSC-derived cells. Specific changes in the niche composition can result in hematological malignancies. Furthermore, processes such as homing, proliferation, and differentiation of HSCs are strongly controlled by the BM niche and have been reported to be related to the success of hematopoietic stem cell transplantation (HSCT). Single-cell sequencing and in vivo imaging are powerful techniques to study BM microenvironment in hematological malignancies and after HSCT. In this review, we discuss how different components of the BM niche, particularly non-hematopoietic and hematopoietic cells, regulate normal hematopoiesis, and changes in the BM niche in leukemia and after HSCT. We believe that this comprehensive review will provide clues for further research on improving HSCT efficiency and exploring potential therapeutic targets for leukemia.

A study of human leukocyte antigen-haploidentical hematopoietic stem cells transplantation combined with allogenic mesenchymal stem cell infusion for treatment of severe aplastic anemia in pediatric and adolescent patients

The clinical applications of human leukocyte antigen (HLA) haploidentical hematopoietic stem cells transplantation (haplo‐HSCT) have offered most of the young severe aplastic anemia (SAA) patients an opportunity to accept curative therapy at the early stage of bone marrow lesions. However, the outcome of juvenile SAA patients received haplo‐HSCT remain to be improved due to high incidence of graft failure and graft vs host disease (GVHD). Mesenchymal stem cells (MSCs) have been characterized by their hematopoiesis‐supporting and immunomodulatory properties. In the current study, we designed a combination of haplo‐HSCT with allogenic MSC for treatment of SAA in pediatric and adolescent patients and evaluated its effects. Juvenile patients (<18 years) with SAA (n = 103) were given HLA‐haploidentical HSC combined with allogenic MSC after a conditioning regimen consisting of busulfan, cyclophosphamide, fludarabine, and antithymocyte globulin and an intensive GVHD prophylaxis, including cyclosporine, short‐term methotrexate, mycophenolate mofetil, and basiliximab. Neutrophil engraftment was achieved in 102 of 103 patients in a median time of 14.3 days (range 9‐25 days). The median time of platelet engraftment was 25.42 days (range 8‐93 days). The cumulative incidence of II‐IV acute GVHD at day +100 was 26.32% ± 0.19% and III‐IV acute GVHD was 6.79% ± 0.06% at day +100, respectively. The cumulative incidence of chronic GVHD was 25.56% ± 0.26%. The overall survival was 87.15% ± 3.3% at a median follow‐up of 40 (1.3‐98) months. Our data suggest that cotransplantation of HLA‐haploidentical HSC and allogenic mesenchymal stem cell may provide an effective and safe treatment for children and adolescents with SAA who lack matched donors.

Tumor necrosis factor α in aGVHD patients contributed to the impairment of recipient bone marrow MSC stemness and deficiency of their hematopoiesis-promotion capacity

Background

Though accumulated evidence has demonstrated visceral organ involvement in acute graft-versus-host disease (aGVHD), how aGVHD influences the bone marrow (BM) niche and the reconstitution of hematopoiesis post-hematopoietic stem cell transplantation remains largely unknown.

Methods

In the current study, the cell morphology, immunophenotype, multi-differentiation capacity, self-renewal capacity, and hematopoiesis promotion of the MSCs from aGVHD and non-aGVHD patients were investigated. Additionally, the stemness and hematopoiesis-promoting property of healthy donor-derived MSCs were evaluated in the presence of BM supernatant from aGVHD patients. Mechanistically, antibodies targeting inflammatory cytokines involved in aGVHD were added into the MSC culture. Furthermore, a recombinant human tumor necrosis factor (TNF-α) receptor-Ig fusion protein (rhTNFR:Fc) was used to protect healthy donor-derived MSCs. Moreover, mRNA sequencing was performed to explore the underlying mechanisms.

Results

The aGVHD MSCs exhibited morphological and immunophenotypic characteristics that were similar to those of the non-aGVHD MSCs. However, the osteogenic and adipogenic activities of the aGVHD MSCs significantly decreased. Additionally, the colony formation capacity and the expression of self-renewal-related genes remarkably decreased in aGVHD MSCs. Further, the hematopoiesis-supporting capacity of aGVHD MSCs significantly reduced. The antibody neutralization results showed that TNF-α contributed to the impairment of MSC properties. Moreover, rhTNFR:Fc exhibited notable protective effects on MSCs in the aGVHD BM supernatants. The mRNA sequencing results indicated that the TNF-α pathway and the Toll-like receptor pathway may be activated by TNF-α.

Conclusions

Thus, our data demonstrate MSCs as cellular targets of aGVHD and suggest a potential role of TNF-α blockage in maintaining the BM niche of aGVHD patients.

Optimization of the Platelet-Rich Plasma Concentration for Mesenchymal Stem Cell Applications

IMPACT STATEMENT

In the current study, we screened the effects of different concentrations of platelet-rich plasma (PRP) on the mesenchymal stem cell (MSC) proliferation and differentiation. Our data demonstrated that concentrated PRP exerted different effects on cell proliferation and on the osteogenic, adipogenic, and chondrogenic differentiation of human bone marrow-derived MSCs. Meanwhile, we optimized PRP concentrations for each of these lineage differentiation and MSC expansion and, thus, suggested several promising clinical strategies for different kinds of diseases. These findings may help explain the controversial effects of PRP on MSCs and improve the progress in precise applications of PRP-based regenerative strategies.

Radial shockwave treatment promotes human mesenchymal stem cell self-renewal and enhances cartilage healing

BACKGROUND

Shockwaves and mesenchymal stem cells (MSCs) have been widely accepted as useful tools for many orthopedic applications. However, the modulatory effects of shockwaves on MSCs remain controversial. In this study, we explored the influence of radial shockwaves on human bone marrow MSCs using a floating model in vitro and evaluated the healing effects of these cells on cartilage defects in vivo using a rabbit model.

METHODS

MSCs were cultured in vitro, harvested, resuspended, and treated with various doses of radial shockwaves in a floating system. Cell proliferation was evaluated by growth kinetics and Cell Counting Kit-8 (CCK-8) assay. In addition, the cell cycle and apoptotic activity were analyzed by fluorescence activated cell sorting. To explore the "stemness" of MSCs, cell colony-forming tests and multidifferentiation assays were performed. We also examined the MSC subcellular structure using transmission electron microscopy and examined the healing effects of these cells on cartilage defects by pathological analyses.

RESULTS

The results of growth kinetics and CCK-8 assays showed that radial shockwave treatment significantly promoted MSC proliferation. Enhanced cell growth was also reflected by an increase in the numbers of cells in the S phase and a decrease in the numbers of cells arrested in the G0/G1 phase in shockwave-treated MSCs. Unexpectedly, shockwaves caused a slight increase in MSC apoptosis rates. Furthermore, radial shockwaves promoted self-replicating activity of MSCs. Transmission electron microscopy revealed that MSCs were metabolically activated by shockwave treatment. In addition, radial shockwaves favored MSC osteogenic differentiation but inhibited adipogenic activity. Most importantly, MSCs pretreated by radial shockwaves exhibited an enhanced healing effect on cartilage defects in vivo. Compared with control groups, shockwave-treated MSCs combined with bio-scaffolds significantly improved histological scores of injured rabbit knees.

CONCLUSIONS

In the present study, we found that radial shockwaves significantly promoted the proliferation and self-renewal of MSCs in vitro and safely accelerated the cartilage repair process in vivo, indicating favorable clinical outcomes.

Subchondral bone derived mesenchymal stem cells display enhanced osteo-chondrogenic differentiation, self-renewal and proliferation potentials

Rabbit mesenchymal stem cells (MSCs) are important seed cells in regenerative medicine research, particularly in translational research. In the current study, we showed that rabbit subchondral bone is a reliable source of MSCs. First, we harvested subchondral bone (SCB) from the rabbit knee-joint and initiated the MSC culture by cultivating enzyme-treated SCB. Adherent fibroblast-like cells that outgrew from SCB fulfill the common immuno-phenotypic criteria for defining MSCs, but with low contamination of CD45+ hematopoietic cells. Interestingly, differentiated SCB-MSCs expressed osteogenic and chondrogenic markers at significantly higher levels than those in bone marrow cell suspension-derived MSCs (BMS-MSCs) (P<0.05). No differences in the expression of adipogenic markers between SCB-MSC and BMS-MSC (P>0.05) were observed. Moreover, the results of the colony forming unit-fibroblast assay and sphere formation assay demonstrated that the SCB-MSCs had increased self-renewal potential. SCB-MSCs expressed higher levels of the stemness markers Nanog, OCT4, and Sox-2 compared to in BMS-MSCs (P<0.05). Furthermore, the results of both the CCK-8-based assay and CFSE dilution assay showed that SCB-MSCs exhibited enhanced proliferative capacity. In addition, SCB-MSCs exhibited higher phosphorylation of extracellular signal-related kinase/mitogen-activated protein kinase signaling, which is closely related to MSC proliferation. In conclusion, we identified SCB-MSCs as a novel stem cell population that met the requirements of MSCs; the unique properties of SCB-MSC are important for the potential treatment of tissue damage resulting from disease and trauma.

Novel insights into a treatment for aplastic anemia based on the advanced proliferation of bone marrow‑derived mesenchymal stem cells induced by fibroblast growth factor 1

Aplastic anemia (AA) is rare disease that is predominantly observed in adolescents. Without effective management at an early stage, is associated with a high risk of mortality. Bone marrow mesenchymal stem cells (BMSCs) can differentiate into various types of cell, which are able to produce a number of hematopoietic growth factors considered to be important in AA alleviation. However, the mechanism underlying the role of fibroblast growth factor 1 (FGF1) in BMSC differentiation remains unknown. In the current study, the investigation focused on the regulatory role and potential signaling pathway of FGF1 in BMSC differentiation in patients exhibiting AA. BMSCs were infected with Ad‑FGF1 and presented a potent proliferation capability, which was evaluated using Cell Counting kit‑8 analysis. Reverse transcription‑quantitative polymerase chain reaction revealed that long non‑coding (lnc)RNA of testis development related gene 1 (TDRG1) was significantly upregulated, demonstrating high expression at the transcriptional level in the BMSCs that were infected with Ad‑FGF1. The decreased proliferation capability of BMSCs that were treated with Ad‑FGF1 and TDRG1‑small interfering RNA validated the vital effect of TDRG1 on the FGF1 regulatory process of BMSC differentiation. Further experiments revealed that the increase of acetyl‑histones, H3 and H4 was diminished in the TDRG1 promoter of BMSCs that were infected with Ad‑FGF1, which indicated that the process of acetylation was promoted when the BMSCs were infected with Ad-FGF1. Thus, it was inferred that FGF1 induces the proliferation of BMSCs in patients with AA via promoting acetylation in lncRNA of the TDRG1 gene promoter.