Human Stem Cell Transplantation Research Articles

Current trends in the treatment of aplastic anemia

Aplastic anemia is a syndrome characterized by reduced hematopoietic stem cells, bone marrow hypoplasia, and pancytopenia, and is often considered a T-cell-mediated autoimmune disease. It is predominantly treated with hematopoietic stem cell transplantation and immunosuppressive therapy with anti-human thymocyte immunoglobulin (ATG) and cyclosporine. Only rabbit ATG was previously available in Japan, but equine ATG was recently approved for use in 2023. Thrombopoietin receptor agonists available in Japan are oral eltrombopag and injectable romiplostim. In hematopoietic stem cell transplantation for aplastic anemia, a conditioning regimen of reduced-dose cyclophosphamide and fludarabine has been used to reduce cardiotoxicity. Human leukocyte antigen haploidentical stem cell transplants have also been developed, and their use in patients without a donor is increasingly reported. Future advancements in novel drugs and transplantation therapies could revolutionize the management of aplastic anemia.

Effect of Combination Electroacupuncture and Tenuigenin on the Migration and Differentiation of Mesenchymal Stem Cells following Ischemic Stroke.

Since stroke is a serious health issue, novel therapeutic strategies are required. In a mouse model of ischemic stroke, this study analyzed the potential of electroacupuncture (EA) and tenuigenin (TE) to improve the efficacy of human mesenchymal stem cell (hMSC) transplantation. Middle cerebral artery occlusion (MCAO) with reperfusion was used to generate ischemic stroke. Forty-eight male C57BL/6 mice were randomly divided into five groups control, MCAO-operated, MCAO-EA, MCAO-TE, or MCAO + EA + TE. Subsequently, hMSCs were transplanted into the ischemic region and EA, TE, or the combination was administered. Behavior assessments and immunohistochemistry were conducted to evaluate motor and cognitive recovery and hMSCs survival, migration, and differentiation. The combined treatment of EA and TE exhibited enhanced hMSCs survival, migration and differentiation into neural cell lineages while suppressing astrocyte formation. Immunohistochemistry demonstrated increased neurogenesis through hMSCs transplantation in the ischemic brain. Immediate behavioral improvements were not significantly different between groups, but there was a gradual recovery in motor and cognitive function over time. These findings highlight the potential of EA and TE co-treatment as a therapeutic strategy for ischemic stroke, opening avenues for further research to optimize treatment protocols and elucidate underlying mechanisms.

Transplantation of human placental chorionic plate-derived mesenchymal stem cells for repair of neurological damage in neonatal hypoxic-ischemic encephalopathy.

JOURNAL/nrgr/04.03/01300535-202409000-00035/figure1/v/2024-01-16T170235Z/r/image-tiff Neonatal hypoxic-ischemic encephalopathy is often associated with permanent cerebral palsy, neurosensory impairments, and cognitive deficits, and there is no effective treatment for complications related to hypoxic-ischemic encephalopathy. The therapeutic potential of human placental chorionic plate-derived mesenchymal stem cells for various diseases has been explored. However, the potential use of human placental chorionic plate-derived mesenchymal stem cells for the treatment of neonatal hypoxic-ischemic encephalopathy has not yet been investigated. In this study, we injected human placental chorionic plate-derived mesenchymal stem cells into the lateral ventricle of a neonatal hypoxic-ischemic encephalopathy rat model and observed significant improvements in both cognitive and motor function. Protein chip analysis showed that interleukin-3 expression was significantly elevated in neonatal hypoxic-ischemic encephalopathy model rats. Following transplantation of human placental chorionic plate-derived mesenchymal stem cells, interleukin-3 expression was downregulated. To further investigate the role of interleukin-3 in neonatal hypoxic-ischemic encephalopathy, we established an in vitro SH-SY5Y cell model of hypoxic-ischemic injury through oxygen-glucose deprivation and silenced interleukin-3 expression using small interfering RNA. We found that the activity and proliferation of SH-SY5Y cells subjected to oxygen-glucose deprivation were further suppressed by interleukin-3 knockdown. Furthermore, interleukin-3 knockout exacerbated neuronal damage and cognitive and motor function impairment in rat models of hypoxic-ischemic encephalopathy. The findings suggest that transplantation of hpcMSCs ameliorated behavioral impairments in a rat model of hypoxic-ischemic encephalopathy, and this effect was mediated by interleukin-3-dependent neurological function.

Platelet Subpopulations and Distinct Platelet Function Defects after Hematopoietic Stem Cell Transplantation in Mice and Humans

Allogeneic hematopoietic stem cell transplantation (HSCT) is often accompanied by bleeding complications due to delayed platelet engraftment. Despite having prolonged thrombocytopenia, patients can also develop thrombotic events. The mechanisms leading to HSCT-related hemorrhage and thrombosis, and especially platelet activity in these patients are yet unknown. Our study aimed to decipher post HSCT megakaryocyte (MK) engraftment and platelet function in a murine model of bone marrow transplantation (BMT) and in patients undergoing HSCT. C57BL/6 mice were lethally irradiated with 10 Gy total body irradiation prior to BMT. Radiation exposure led to massive BM remodeling, including extracellular matrix degradation, vasodilation and aberrant pericyte morphology, accompanied by extensive ectopic platelet release into the BM cavity, which might contribute to thrombocytopenia. We used Actb dsRed reporter mice as BM donors allowing us to track all donor-derived (dsRed +) cells after BMT. Femurs were removed after 14 days and subjected to confocal laser immunofluorescence microscopy using lineage-specific markers. While we found an overall homogenous engraftment pattern for red blood cells and most leukocyte sub-lineages, the engraftment pattern for MKs and Ly6G + cells was characterized by long triangular clusters at the bone cortex. We manipulated BM engraftment by transplanting different numbers of graft cells. Within 2 weeks after BMT with 6 x 10 6 BM cells per mouse, a complete chimerism was achieved for both MKs in BM and platelets in peripheral blood. These newly formed platelets had an increased platelet size, while the surface expression levels (CD41/CD42/GPVI) were decreased by half, implying a massive reduction in receptor density. Flow cytometry analyses of agonist-stimulated platelets revealed a severely impaired granule release and integrin activation that was confirmed by aggregometry. When only 1 x 10 6 BM cells per mouse were transplanted, we found an extended mixed MK chimerism after BMT. During the first 28 days, we detected both dsRed - (recipient-derived) and dsRed + (donor-derived) MKs in the recipient BM and, concomitantly, dsRed - and dsRed + platelets in peripheral blood. Unexpectedly, we observed opposing agonist-induced platelet reactivity with hyporeactive dsRed - platelets, while dsRed + platelets were hyperreactive, indicating that 2 BM MK subpopulations generate 2 functionally distinct platelet subpopulations. Intriguingly, we found an upregulation of annexin V binding on dsRed -, but not on dsRed + resting platelets, implying that the myeloablative conditions preceding HSCT result in increased phosphatidylserine (PS) exposure, a key sign of pro-coagulant platelets. In vitro thrombus formation was assessed under flow using a whole blood collagen-coated microfluidic device. While surface coverage was mildly increased, thrombus volume remained comparable to controls. dsRed + platelets exhibited a distinct incorporation pattern by preferentially attaching to the edges of growing thrombi, indicating that dsRed - and dsRed + platelets may differ in thrombus initiation and growth. While platelet count and other blood cell parameters are routinely monitored in HSCT patients, the functional capacity of graft-derived platelets has not yet been systematically assessed. We thus performed extended platelet function analyses in 13 adult patients (aged 24-73 years) undergoing allogeneic HSCT for malignant leukemic diseases (mostly acute myeloid leukemia) and detected a massive platelet hyporeactivity for up to 100 days observation time after HSCT. Integrin activation was severely impaired upon stimulation of PAR-1 or GPVI. In contrast to mice, α granule release, monitored by P-selectin neo-exposure, was only slightly reduced compared to healthy controls, suggesting a decoupling of integrin activation and P-selectin exposure. In line with our findings in mice, we detected a pronounced upregulation in the proportion of pro-coagulant PS-positive platelets with a reduced mitochondrial membrane potential. Our data demonstrate that a mixed chimerism after HSCT results in two co-existing platelet subpopulations with opposing response profiles. This unexpected finding provides the first experimental evidence why bleedings and thromboembolic events can both occur after HSCT and hints toward pro-coagulant platelets as a potential therapeutic target.

175. Clindamycin versus linezolid for Group A Streptococcal bloodstream infections?: A comparative effectiveness study of adjunctive antitoxin therapy at 137 US Hospitals

Abstract Background Adjunctive clindamycin has survival benefit in invasive Group A streptococcus (GAS) infections. Like clindamycin, linezolid also leads to decreased toxin and virulence factor production. However, rising clindamycin resistance among GAS isolates and inadequate clinical data on linezolid both offer pause on which to choose. We examined the impact of adjunctive clindamycin vs. linezolid on survival among patients with GAS bloodstream infections (BSI) in the presence and absence of clindamycin resistant (clinda-R) isolates Methods Clinical characteristics, antimicrobial susceptibility testing (AST), and antibiotic therapy were examined for unique adult inpatient encounters with GAS BSIs in the PINC-AI Database. Patients treated with a β-lactam for ≥3 days ±3 days of culture who received clindamycin ±3 days of culture were overlap weighted on a propensity-score to those who received linezolid using basine patient and hospital factors. The primary outcome was odds ratio (OR) of in-hospital mortality associated with clindamycin (vs linezolid). The secondary outcome was length of stay (LOS) among survivors. Subgroups analyses were conducted excluding clindamycin receipients with clinda-R isolates (subgroup 1) and also missing clindamycin AST(including D-test; subgroup 2).Figure 1.Study Flow chart Selection of patients with Group A streptococcal blood stream infections. The database was queried for inpatients (aged ≥18 years) with blood culture displaying growth of Group A streptococcus, filtered on the basis of receiving β-lactam antibiotics within 3 days either side of culture sampling for a minimum duration of 3 days and received either adjunctive clindamycin or linezolid treatment within 3 days either side of culture sampling.Table 1:Baseline characteristics of all patients with Group A Streptococcal blood stream infections treated with β-lactam antibiotics and adjunctive clindamycin or linezolid (N=660)Abbreviations: IVIG: intravenous immunoglobulin, ICU: intensive care unit, IQR: interquartile range, SOFA: Sequential Organ Failure Assessment * This score was calculated by use of ICD-10-clinical modification codes and adapted from the methods used by Quan and colleagues ^ Calculated by use of an electronic health record-based adaption of the original Sequential Organ Failure Assessment ^^ Deteremined by clindamycin antimicrobial susceptibility and D-test results. Defined as resistant or intermediate clindamycin susceptibility results and/or a positive D-test result. † Defined as presence of ICD-10 codes coding for any of the following conditions: Human immunodeficiency virus, cancer, solid organ or hematopoietic stem cell transplantation, receipt of systemic corticosteroids, chemotherapy or other immunosuppressive therapy and immunodeficiency. ‡ Receipt of norepinephrine, epinephrine, phenylephrine, and dopamine administered within a 24-h period either side of culture sampling. Results Of 3019 β-lactam–treated inpatients with GAS BSI, 500 (17%) received clindamycin and 160 (5%) received linezolid. The prevalence of clinda-R isolates was 19%;1 isolate was linezolid resistant and excluded (Figure 1). Overlap weighting resulted in well balanced groups (Figure 2). In the overlap weighted cohort, mortality risk was similar between recipients of clindamycin (10%, [50/500]) vs linezolid (9%, [14/160]; OR 1.38 [95% CI: 0.76-2.49]). Among survivors median[interquartile range] LOS was similar between the two groups (8[9] vs. 9[8] days, p=0.45). Removing those with clinda-R isolates (N=84) and also missing AST (N=166) yielded similar results (Figure 3).Figure 2.Standardized mean differences for covariates included the propensity score calculation Standardized mean differences for covariates included in the propensity score generation averaged across exposure categories in the unweighted cohort (blue triangles) and overlap weighted cohort weight (red circles). After overlap weighting, the mean standard difference at each variable assessed was zero . Abbreviations: ICU: intensive care unit, IVIG: intravenous immunoglobulin, NSTI: necrotizing soft tissue infectionFigure 3.Odds Ratio of in-hospital mortality in patients with invasive group A streptococcal blood stream infection treated with adjunctive clindamycin versus adjunctive linezolid The ORs (95% CIs) of in-hospital mortality (including discharge to hospice) in the primary analysis and subgroup analysis with patients withclindamycin resistant isolates (subgroup 1) and those with clindamycin resistant isolates and missing clindamycin susceptibility results (subgroup 2) removed from clindamycin group. Abbreviations: CI: confidence interval Conclusion Among β-lactam-treated patients with GAS BSI, linezolid and clindamycin displayed comparable effectiveness as adjunctive antitoxin agents. Similar intrinsic effectiveness (i.e., in patients with only susceptible isolates) supports linezolid as an alternative even in low clinda-R settings. Disclosures Ahmed Babiker, MBBS, Roche: Advisor/Consultant Morgan Walker, MD, Cytovale: Advisor/Consultant

Racial Disparity in Hematopoietic Stem Cell Transplant Clinical Trial Recruitment

Introduction: Race significantly influences phenotypic and genetic diversity in hematological diseases, consequently affecting disease prognosis, Human Leukocyte Antigen-matching and Hematopoietic Stem Cell Transplant (HSCT) outcomes. To ensure the development of novel transplant strategies effective for patients from diverse backgrounds, all racial groups must have equal opportunities to take part in HSCT clinical trials. Methods: Using ClinicalTrials.gov, a web-based resource that registers all studies meeting the definition of a clinical trial according to the International Committee on Medical Journal Editors, we identified all phase 1 to phase 4 HSCT clinical trials registered from 2006 to 2022. We manually abstracted data on the racial distribution of enrolled participants, sex distribution, transplant type, trial phase, location, and year of trial reporting. We calculated observed ratios of racial participation and compared them with the estimated probability of finding adequate donors from different racial subgroups reported by the National Marrow Donor Program to define the disproportionate enrolment factor. We then conducted subgroup racial distribution based on the trial phase, location, and type of transplant. We further evaluated trends in racial disparity within clinical trial enrolment over the years. Results: We identified 398 clinical trials related to HSCT between 2006 and 2022, of which 72% were allogenic and 28% were autologous HSCT trials. Most of these were phase 2 clinical trials (64.3%) and the majority (78.1%) were conducted in the United States. The racial distribution of enrolled participants was publicly available in 235 (59%) of these clinical trials, including 57.7% allogeneic and 62.5% autologous HSCT. The race distribution of enrolled subjects was reported in 80% of Phase 1 and 79% of Phase 3, whereas only 48% of Phase 1/2 and 44% of Phase 2/3 clinical trials reported racial distribution. The race distribution among 25,075 study participants in 235 clinical trials was: 80.4% Whites (20,175), 7.4% Blacks (1858), 5.3% Asians (1336), 1.6% other races (396), and 5.3% (1310) subjects with unreported race. The same race distribution trend was observed across all subgroups of clinical trials based on phase, location, and transplant type (Table 1). The disproportionate enrolment factor was 0.27 for Black participants, and 0.11 for Asian participants, compared to 1.02 for Whites. From 2006 to 2022, yearly trends for the absolute number of clinical trial enrollees showed a 2.5% and 1.5% increase in Black and Asian subject representation; however, minorities still accounted for only 20.3% of total representation in 2022 (Figure 1). Conclusions: Our results emphasize the significant racial underrepresentation of minority populations with a very low disproportionate enrolment factor in HSCT clinical trials despite the increased probability of finding a suitable donor resulting from novel HSCT technologies in recent years. Addressing these disparities requires urgent action and a multi-faceted approach. Efforts such as targeted outreach, cultural competence training and community engagement to focus on eliminating barriers are urgently needed to increase the enrolment of the minority population to achieve racial equity in HSCT.

Conditioned medium from human dental pulp stem cells treats spinal cord injury by inhibiting microglial pyroptosis.

Human dental pulp stem cell transplantation has been shown to be an effective therapeutic strategy for spinal cord injury. However, whether the human dental pulp stem cell secretome can contribute to functional recovery after spinal cord injury remains unclear. In the present study, we established a rat model of spinal cord injury based on impact injury froma dropped weight and then intraperitoneally injected the rats with conditioned medium from human dental pulp stem cells. We found that the conditioned medium effectively promoted the recovery of sensory and motor functions in rats with spinal cord injury, decreased expression of the microglial pyroptosis markers NLRP3, GSDMD, caspase-1, and interleukin-1β, promoted axonal and myelin regeneration, and inhibited the formation of glial scars. In addition, in a lipopolysaccharide-induced BV2 microglia model, conditioned medium from human dental pulp stem cells protected cells from pyroptosis by inhibiting the NLRP3/caspase-1/interleukin-1β pathway. These results indicate that conditioned medium from human dental pulp stem cells can reduce microglial pyroptosis by inhibiting the NLRP3/caspase-1/interleukin-1β pathway, thereby promoting the recovery of neurological function after spinal cord injury. Therefore, conditioned medium from human dental pulp stem cells may become an alternative therapy for spinal cord injury.

Injectable collagen scaffold with human umbilical cord-derived mesenchymal stem cells promotes functional recovery in patients with spontaneous intracerebral hemorrhage: phase I clinical trial.

Animal experiments have shown that injectable collagen scaffold with human umbilical cord-derived mesenchymal stem cells can promote recovery from spinal cord injury. To investigate whether injectable collagen scaffold with human umbilical cord-derived mesenchymal stem cells can be used to treat spontaneous intracerebral hemorrhage, this non-randomized phase I clinical trial recruited patients who met the inclusion criteria and did not meet the exclusion criteria of spontaneous intracerebral hemorrhage treated in the Characteristic Medical Center of Chinese People's Armed Police Force from May 2016 to December 2020. Patients were divided into three groups according to the clinical situation and patient benefit: control (n = 18), human umbilical cord-derived mesenchymal stem cells (n = 4), and combination (n = 8). The control group did not receive any transplantation. The human umbilical cord-derived mesenchymal stem cells group received human umbilical cord-derived mesenchymal stem cell transplantation. The combination group received injectable collagen scaffold with human umbilical cord-derived mesenchymal stem cells. Patients who received injectable collagen scaffold with human umbilical cord-derived mesenchymal stem cells had more remarkable improvements in activities of daily living and cognitive function and smaller foci of intracerebral hemorrhage-related encephalomalacia. Severe adverse events associated with cell transplantation were not observed. Injectable collagen scaffold with human umbilical cord-derived mesenchymal stem cells appears to have great potential treating spontaneous intracerebral hemorrhage.

HUC-MSC transplantation therapy effects on lupus-prone MRL/lpr mice at early disease stages

BackgroundThe efficacy of human umbilical cord mesenchymal stem cell (hUC-MSC) transplantation in treating systemic lupus erythematosus (SLE) has been confirmed by small-scale clinical trials. However, these trials focused on severe or refractory SLE, while few studies focused on mild SLE. Therefore, this study focused on the therapeutic effects of hUC-MSC transplantation in early-stage or mild MRL/lpr lupus model mice.MethodsCommercially available hUC-MSCs were transplanted into 8-week-old MRL/lpr mice by tail vein injection. Flow cytometry was used to analyze B cells and their subsets in the peripheral blood. Further, plasma inflammatory factors, autoantibodies, and plasma biochemical indices were detected using protein chip technology and ELISA kits. In addition, pathological staining and immunofluorescence were performed to detect kidney injury in mice.ResultshUC-MSC transplantation did not affect the mice’s body weight, and both middle and high dose hUC-MSC transplantation (MD and HD group) actually reduced spleen weight. hUC-MSC transplantation significantly decreased the proportion of plasmablasts (PB), IgG1− PB, IgG1+ PB, IgG1+ memory B (MB) cells, IgG1+ DN MB, and IgG1+ SP MB cells. The hUC-MSC transplantation had significantly reduced plasma levels of inflammatory factors, such as TNF-α, IFN-γ, IL-6, and IL-13. Pathological staining showed that the infiltration of glomerular inflammatory cells was significantly reduced and that the level of glomerular fibrosis was significantly alleviated in hUC-MSC-transplanted mice. Immunofluorescence assays showed that the deposition of IgG and IgM antibodies in the kidneys of hUC-MSC-transplanted mice was significantly lower than in the control.ConclusionhUC-MSC transplantation could inhibit the proliferation and differentiation of peripheral blood B cells in the early-stage of MRL/lpr mice, thereby alleviating the plasma inflammatory environment in mice, leading to kidney injury remission. The study provides a new and feasible strategy for SLE treatment.

How to optimize outcome of patients undergoing HLA-matched related haematopoietic stem cell transplantation in acquired and inherited bone marrow failure syndromes.

Up-front allogeneic haematopoietic stem cell transplantation (allo-HSCT) after a reduced intensity conditioning regimen is the standard treatment in children with acquired severe aplastic anaemia (aSAA) and inherited bone marrow failure syndromes (iBMFs) in the presence of a healthy matched related donor (MRD). The paper by Alsultan et al. report the safety and efficacy of MRD HSCT conditioned with low-dose cyclophosphamide, fludarabine and thymoglobulin in both aSAA and non-Fanconi iBMFs, strengthening the concept of the pivotal role of immunosuppressive approach in allo-HSCT for specific subgroups of non-malignant diseases requiring a reduced risk of toxicities, offering the opportunity to discuss the essential points for achieving patients' long-term survival after MRD HSCT in BMF. Commentary on: Alsultan et al. Human leucocyte antigen-matched related haematopoietic stem cell transplantation using low-dose cyclophosphamide, fludarabine and thymoglobulin in children with severe aplastic anaemia. Br J Haematol 2023;203:255-263.

The Dose-Related Efficacy of Human Placenta-Derived Mesenchymal Stem Cell Transplantation on Antioxidant Effects in a Rat Model with Ovariectomy.

Oxidative stress initiates various degenerative diseases, and it is caused by excessive reactive oxygen species (ROS) production. Oxidative stress is a key factor that causes infertility by inducing ovarian dysfunction, characterized by irregular hormone levels, lower quality of mature follicles, and loss of follicles. Hence, stem cell therapy has been actively studied as an approach to overcome the side effects of hormone replacement therapy (HRT) on ovarian dysfunction. However, there is a lack of evidence about the appropriate number of cells required for stem cell therapy. Therefore, based on the antioxidant effects investigated in this study, we focused on determining the appropriate dose of stem cells for transplantation in an animal model with ovarian dysfunction. One week after half-ovariectomy, placenta-derived mesenchymal stem cells (PD-MSCs, 1 × 105 cells, 5 × 105 cells, or 2.5 × 106 cells) were injected intravenously into the Tx groups through the tail vein. As a result, the mRNA expression of hAlu gradually increased as the transplanted cell concentration increased. Compared with no transplantation (NTx), the transplantation of PD-MSCs improved folliculogenesis, including the levels of secreted hormones and numbers of follicles, by exerting antioxidant effects. Also, the levels of oxidized glutathione in the serum of animal models after transplantation were significantly increased (* p < 0.05). These results indicated that PD-MSC transplantation improved ovarian function in half-ovariectomized rats by exerting antioxidant effects. According to our data, increasing the number of transplanted cells did not proportionally increase the effectiveness of the treatment. We suggest that low-dose PD-MSC transplantation has the same therapeutic effect as described in previous studies. These findings provide new insights for further understanding reproductive systems and provide evidence for related clinical trials.

Potential optimized route for mesenchymal stem cell transplantation in a rat model of cerebral palsy

Cerebral palsy (CP) is a movement and posture disorder that affects over 50 million people worldwide. Human umbilical cord-derived mesenchymal stem cell (hUC-MSC) transplantation has emerged as an attractive therapeutic strategy for CP. The administration route appears to be crucial for hUC-MSC to provide adequate neuroprotection. Wistar rats were given hypoxia-ischemia to make the CP model on postnatal day 5. On postnatal day 21, DiR-labeled hUC-MSC were transplanted into the CP rats by intravenous, intrathecal, and lateral ventricle for cell tracking. Uninfused CP rats served as the negative control. The motor behavioral and pathological alteration was analyzed 11, 25, and 39 days after transplantation to assess motor function, immune inflammation, neurotrophy, and endogenous repair. In vivo imaging tracking techniques revealed that intravenous infusion resulted in fewer transplanted cells in the target brain than intrathecal and lateral ventricle infusion (p＜0.05). Three different routes of hUC-MSC infusion improved the motor function of CP rats (p＜0.05). At 11 days post-infusion, intrathecal infusion outperformed intravenous with a significant neurotrophic and oligodendrocyte maturation effect (p＜0.05). Intrathecal infusion equaled lateral ventricle infusion after 25 days. At 39 days post-infusion, lateral ventricle infusion exceeded intravenous and intrathecal infusion with a significant immunosuppressive effect (p＜0.05). Considering the improved effect and less trauma shown early in the intrathecal infusion, repeated intrathecal administration may ultimately lead to the greatest benefit.

Human leucocyte antigen-matched related haematopoietic stem cell transplantation using low-dose cyclophosphamide, fludarabine and thymoglobulin in children with severe aplastic anaemia.

When human leucocyte antigen-matched related donors are available, haematopoietic stem cell transplantation (HSCT) in children with severe aplastic anaemia (SAA) represents the standard of care. Cyclophosphamide (Cy) 200 mg/kg and anti-thymocyte globulin (ATG) are frequently administered, but to-date, no standard conditioning regimen exists. In this study, we investigated the efficacy of a unified HSCT conditioning protocol consisting of low-dose Cy 80 mg/kg, fludarabine and ATG. Data were reviewed from children aged ≤14 years with either acquired SAA or non-Fanconi anaemia inherited bone marrow failure syndrome (IBMFS) between 2011 and 2022 at various Saudi institutions. Graft-versus-host disease (GVHD) prophylaxis included mycophenolate mofetil and calcineurin inhibitors. HSCT was performed in 32 children (17 females and 15 males). Nine patients had deleterious mutations (two ERCC6L2, two ANKRD26, two TINF2, one LZTFL1, one RTEL1 and one DNAJC21). Four patients had short telomeres. All 32 patients engrafted successfully. At 3 years post-transplant, the event-free survival was 93% and overall survival was 95%. Two patients experienced secondary graft failure or myelodysplastic syndrome. A low probability of GVHD was observed (one acute GVHD II and one mild chronic GVHD). These data highlight how HSCT using low-dose Cy as part of a fludarabine-based regimen is safe and effective in SAA/non-Fanconi anaemia IBMFS.

Transplantation of Human Brain-Derived Ischemia-Induced Multipotent Stem Cells Ameliorates Neurological Dysfunction in Mice After Stroke.

We recently demonstrated that injury/ischemia-induced multipotent stem cells (iSCs) develop within post-stroke human brains. Because iSCs are stem cells induced under pathological conditions, such as ischemic stroke, the use of human brain-derived iSCs (h-iSCs) may represent a novel therapy for stroke patients. We performed a preclinical study by transplanting h-iSCs transcranially into post-stroke mouse brains 6 weeks after middle cerebral artery occlusion (MCAO). Compared with PBS-treated controls, h-iSC transplantation significantly improved neurological function. To identify the underlying mechanism, green fluorescent protein (GFP)-labeled h-iSCs were transplanted into post-stroke mouse brains. Immunohistochemistry revealed that GFP+ h-iSCs survived around the ischemic areas and some differentiated into mature neuronal cells. To determine the effect on endogenous neural stem/progenitor cells (NSPCs) by h-iSC transplantation, mCherry-labeled h-iSCs were administered to Nestin-GFP transgenic mice which were subjected to MCAO. As a result, many GFP+ NSPCs were observed around the injured sites compared with controls, indicating that mCherry+ h-iSCs activate GFP+ endogenous NSPCs. In support of these findings, coculture studies revealed that the presence of h-iSCs promotes the proliferation of endogenous NSPCs and increases neurogenesis. In addition, coculture experiments indicated neuronal network formation between h-iSC- and NSPC-derived neurons. These results suggest that h-iSCs exert positive effects on neural regeneration through not only neural replacement by grafted cells but also neurogenesis by activated endogenous NSPCs. Thus, h-iSCs have the potential to be a novel source of cell therapy for stroke patients.

Pulp-Dentin Complex Regeneration with Cell Transplantation Technique Using Stem Cells Derived from Human Deciduous Teeth: Histological and Immunohistochemical Study in Immunosuppressed Rats.

The aim of this study was to histologically verify the performance of pulp-derived stem cells used in the pulp-dentin complex regeneration. Maxillary molars of 12 immunosuppressed rats were divided into two groups: the SC (stem cells) group, and the PBS (just standard phosphate-buffered saline) group. After pulpectomy and canal preparation, the teeth received the designated materials, and the cavities were sealed. After 12 weeks, the animals were euthanized, and the specimens underwent histological processing and qualitative evaluation of intracanal connective tissue, odontoblast-like cells, intracanal mineralized tissue, and periapical inflammatory infiltrate. Immunohistochemical evaluation was performed to detect dentin matrix protein 1 (DMP1). In the PBS group, an amorphous substance and remnants of mineralized tissue were observed throughout the canal, and abundant inflammatory cells were observed in the periapical region. In the SC group, an amorphous substance and remnants of mineralized tissue were observed throughout the canal; odontoblasts-like cells immunopositive for DMP1 and mineral plug were observed in the apical region of the canal; and a mild inflammatory infiltrate, intense vascularization, and neoformation of organized connective tissue were observed in the periapical region. In conclusion, the transplantation of human pulp stem cells promoted partial pulp tissue neoformation in adult rat molars.

Recovery of the Functional Activity of K&lt;sub&gt;ATP&lt;/sub&gt;-Channels of Pial Arteries after Ischemia/Reperfusion Using Cell Therapy

This study aims to examine the efficiency of intravenous transplantation of human mesenchymal stem cells (hMSCs) performed 7 days after cerebral ischemia/reperfusion (I/R) for recovery of the functional activity of KATP-channels of cerebral arteries. Using a device for intravital visualization of pial vessels, the reaction of arteries to the KATP-channel blocker glibenclamide (GB), the activator of the same channels of pinacidil (PI), acetylcholine (ACh), and ACh against a background of GB action (ACh/GB) 14 and 21 days after I/R and intravenous hMSC transplantation performed 7 days after ischemic exposure. On exposure to GB 14 days after I/R, 1.5–1.8 times fewer arteries narrowed than in the sham–operated (SO) rats. By day 21 after I/R, the constriction reaction was completely restored, except for arteries with a diameter more 40 μm. In the cell–therapy group, the constrictor response to GB was completely recovered to the level of SO animals in arteries with a diameter less than 40 μm by 14 day after I/R exposure; in arteries with a diameter of more than 40 μm, the constriction reaction did not recover until 21 days. The number of dilations per ACh/GB compared to a clear ACh in SO rats was reduced in 1.6–1.8 times on 14 day after I/R and in 1.6–6.6 after 21 days. In I/R animals on 14 day, the number of dilatations per ACh/GB compared to clear ACh was significantly increased in arteries with a diameter of more than 20 μm by 1.5–1.7 times, and after 21 days in arteries with a diameter of more than 40 μm by 1.2 times. After the introduction of hMSC, GB blocked ACh–mediated dilation in arteries less than 40 μm in diameter both on days 14 and 21 after I/R. In arteries with a diameter of more than 40 μm the functional activity of KATP-channels did not recover until 21 days. Conclusion. I/R of the rat cerebral cortex reduces the contribution of KATP-channels to maintaining the basal tone of the pial arteries and almost completely excludes these channels from the formation of ACh–mediated dilation during 21 days of the postischemic period. Practically did not participate in the dilatory response. Intravenous transplantation of hMSC, performed 7 days after I/R, results in restoration of participation of SMC KATP-channels in maintaining the basal tone and ACh–mediated dilatation of pial arteries with a diameter less than 40 μm already 14 days after I/R.

Presentation of Human Neural Stem Cell Antigens Drives Regulatory T Cell Induction.

Transplantation of human neural stem cells (hNSCs) is a promising regenerative therapy to promote remyelination in patients with multiple sclerosis (MS). Transplantation of hNSCs has been shown to increase the number of CD4+CD25+Foxp3+ T regulatory cells (Tregs) in the spinal cords of murine models of MS, which is correlated with a strong localized remyelination response. However, the mechanisms by which hNSC transplantation leads to an increase in Tregs in the CNS remains unclear. We report that hNSCs drive the conversion of T conventional (Tconv) cells into Tregs invitro. Conversion of Tconv cells is Ag driven and fails to occur in the absence of TCR stimulation by cognate antigenic self-peptides. Furthermore, CNS Ags are sufficient to drive this conversion in the absence of hNSCs invitro and invivo. Importantly, only Ags presented in the thymus during T cell selection drive this Treg response. In this study, we investigate the mechanisms by which hNSC Ags drive the conversion of Tconv cells into Tregs and may provide key insight needed for the development of MS therapies.

The Humanized Mouse Model: What Added Value Does It Offer for HIV Research?

In the early 2000s, novel humanized mouse models based on the transplantation of human hematopoietic stem and progenitor cells (HSPCs) into immunocompromised mice were introduced (hu mice). The human HSPCs gave rise to a lymphoid system of human origin. The HIV research community has greatly benefitted from these hu mice. Since human immunodeficiency virus (HIV) type 1 infection results in a high-titer disseminated HIV infection, hu mice have been of great value for all types of HIV research from pathogenesis to novel therapies. Since the first description of this new generation of hu mice, great efforts have been expended to improve humanization by creating other immunodeficient mouse models or supplementing mice with human transgenes to improve human engraftment. Many labs have their own customized hu mouse models, making comparisons quite difficult. Here, we discuss the different hu mouse models in the context of specific research questions in order to define which characteristics should be considered when determining which hu mouse model is appropriate for the question posed. We strongly believe that researchers must first define their research question and then determine whether a hu mouse model exists, allowing the research question to be studied.

Encapsulation of Human Umbilical Cord Mesenchymal Stem Cells in LunaGel Photocrosslinkable Extracellular Matrix and Subcutaneous Transplantation in Mice

Stem cells have significant potential in regenerative medicines. However, a major issue with implanting stem cells in the regeneration of new tissue is the methods to implant them and cell viability and functions before and after implantation. Here we developed a simple yet effective method that used photo-crosslinkable gelatin-based hydrogel (LunaGelTM) as a scaffold for the encapsulation, expansion, and eventually, transplantation of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) into mice subcutaneously. We demonstrated the proliferation and maintenance of the original expression of mesenchymal stem cell markers as well as the ability to differentiate into mesoderm-derived cells. The hydrogel was highly stable with no signs of degradation after 20 days in PBS. The hUC-MSCs remained viable after transplantation into mice's subcutaneous pockets and migrated to integrate with the surrounding tissues. We showed a collagen-rich layer surrounding the transplanted cell-laden scaffold indicating the effects of growth factors secreted by the hUC-MSCs. A connective tissue layer was found between the implanted cell-laden scaffold and the collagen layer, and immunohistochemical staining results suggested that this tissue was derived from the MSCs which migrated from within the scaffold. The results, thus, also suggested a protective effect the scaffold has on the encapsulated cells from the antibodies and cytotoxic cells of the host immune system.

Reversal of Pulmonary Fibrosis: Human Umbilical Mesenchymal Stem Cells from Wharton's Jelly versus Human-Adipose-Derived Mesenchymal Stem Cells.

Pulmonary fibrosis (PF) is a progressive, non-reversible illness with various etiologies. Currently, effective treatments for fibrotic lungs are still lacking. Here, we compared the effectiveness of transplantation of human mesenchymal stem cells from umbilical cord Wharton's jelly (HUMSCs) versus those from adipose tissue (ADMSCs) in reversing pulmonary fibrosis in rats. Bleomycin 5 mg was intratracheally injected to establish a severe, stable, single left lung animal model with PF. On Day 21 post-BLM administration, one single transplantation of 2.5 × 107 HUMSCs or ADMSCs was performed. Lung function examination of Injury and Injury+ADMSCs rats displayed significantly decreased blood oxygen saturation and increased respiratory rates, while Injury+HUMSCs rats showed statistical amelioration in blood oxygen saturation and significant alleviation in respiratory rates. Reduced cell number in the bronchoalveolar lavage and lower myofibroblast activation appeared in the rats transplanted with either ADMSCs or HUMSCS than that in the Injury group. However, ADMSC transplantation stimulated more adipogenesis. Furthermore, matrix-metallopeptidase-9 over-expression for collagen degradation, and the elevation of Toll-like receptor-4 expression for alveolar regeneration were observed only in the Injury+HUMSCs. In comparison with the transplantation of ADMSCs, transplantation of HUMSCs exhibited a much more effective therapeutic effect on PF, with significantly better results in alveolar volume and lung function.