Non-myeloablative allogeneic hematopoietic stem cell transplantation

Accumulation of Dystrophin-Positive Muscle Fibers and Improvement of Neuromuscular Junctions in mdx Mouse Muscles after Bone Marrow Transplantation under Different Conditions

Duchenne muscular dystrophy (DMD) is a severe muscular disorder caused by mutations in the dystrophin gene. It leads to respiratory and cardiac failure and premature death at a young age. Although recent studies have greatly deepened the understanding of the primary and secondary pathogenetic mechanisms of DMD, an effective treatment remains elusive. In recent decades, stem cells have emerged as a novel therapeutic product for a variety of diseases. In this study, we investigated nonmyeloablative bone marrow cell (BMC) transplantation as a method of cell therapy for DMD in an mdx mouse model. By using BMC transplantation from GFP-positive mice, we confirmed that BMCs participate in the muscle restoration of mdx mice. We analyzed both syngeneic and allogeneic BMC transplantation under different conditions. Our data indicated that 3 Gy X-ray irradiation with subsequent BMC transplantation improved dystrophin synthesis and the structure of striated muscle fibers (SMFs) in mdx mice as well as decreasing the death rate of SMFs. In addition, we observed the normalization of neuromuscular junctions (NMJs) in mdx mice after nonmyeloablative BMC transplantation. In conclusion, we demonstrated that nonmyeloablative BMC transplantation could be considered a method for DMD treatment.

CAR-NKT cell therapy: a new promising paradigm of cancer immunotherapy

Today, cancer treatment is one of the fundamental problems facing clinicians and researchers worldwide. Efforts to find an excellent way to treat this illness continue, and new therapeutic strategies are developed quickly. Adoptive cell therapy (ACT) is a practical approach that has been emerged to improve clinical outcomes in cancer patients. In the ACT, one of the best ways to arm the immune cells against tumors is by employing chimeric antigen receptors (CARs) via genetic engineering. CAR equips cells to target specific antigens on tumor cells and selectively eradicate them. Researchers have achieved promising preclinical and clinical outcomes with different cells by using CARs. One of the potent immune cells that seems to be a good candidate for CAR-immune cell therapy is the Natural Killer-T (NKT) cell. NKT cells have multiple features that make them potent cells against tumors and would be a powerful replacement for T cells and natural killer (NK) cells. NKT cells are cytotoxic immune cells with various capabilities and no notable side effects on normal cells. The current study aimed to comprehensively provide the latest advances in CAR-NKT cell therapy for cancers.

Evaluation of a group-based exercise and relaxation rehabilitation program during hospitalization for allogeneic hematopoietic stem cell transplant

BACKGROUND

Exercise and relaxation interventions have demonstrated benefits in allogeneic hematopoietic stem cell transplant (allo-HSCT) patients; however, little is known about the implementation enablers and barriers for inpatient rehabilitation or its impact on health outcomes.

OBJECTIVE

To conduct a program evaluation of group-based rehabilitation consisting of exercise and relaxation classes for allo-HSCT inpatients.

DESIGN

Prospective program evaluation using the RE-AIM (reach, effectiveness, adoption, implementation, and maintenance) framework.

SETTING

Inpatient hospital unit at a tertiary care center.

PARTICIPANTS

Forty-five adult patients admitted for allo-HSCT.

INTERVENTIONS

Standard of care rehabilitation.

MAIN OUTCOME MEASURES

Program attendance, safety, satisfaction, and fidelity were assessed. Exploratory effectiveness analyses were conducted via the measurement of physical, psychosocial, clinical, and health resource use outcomes at hospital admission and discharge.

RESULTS

Forty-seven of the 63 patients receiving allo-HSCT between November 2019 and March 2020 were consented. Data presented in this publication are from the 33 participants who completed study assessments (high attrition due to cancellation of research during the COVID-19 pandemic). Eighty-two percent of participants attended at least one class; however, 55% of the participants invited to the classes on a daily basis were not able to attend. Barriers to participation included transplant complications, isolation for infection prevention, and fatigue. There were no adverse events associated with the intervention and 82% of participants adhered to the prescribed activities. Participants reported satisfaction with the program and enjoyed the motivational support and social interaction. Between hospital admission and discharge, anxiety scores improved; however, fatigue, depression, grip strength, functional mobility, and quality of life scores declined. Physical activity volume and lower body strength were maintained.

CONCLUSIONS

Group-based exercise and relaxation classes seem to be feasible and safe during hospitalization for allo-HSCT; however, there are pragmatic barriers to be considered for optimal program implementation. Further research examining program effectiveness and adoption is warranted.

Engineering stem cells for cancer immunotherapy

Engineering stem cells presents an attractive paradigm for cancer immunotherapy. Stem cells engineered to stably express various chimeric antigen receptors (CARs) or T-cell receptors (TCRs) against tumor-associated antigens are showing increasing promise in the treatment of solid tumors and hematologic malignancies. Stem cells engraft for long-term immune cell generation and serve as a sustained source of tumor-specific effector cells to maintain remissions. Furthermore, engineering stem cells provides 'off-the-shelf' cellular products, obviating the need for a personalized and patient-specific product that plagues current autologous cell therapies. Herein, we summarize recent progress of stem cell-engineered cancer therapies, and discuss the utility, impact, opportunities, and challenges of cellular engineering that may facilitate the translational and clinical research.

Long-Lasting Impact of Neonatal Exposure to Total Body Gamma Radiation on Secondary Lymphoid Organ Structure and Function

The acute period after total body irradiation (TBI) is associated with an increased risk of infection, principally resulting from the loss of hematopoietic stem cells, as well as disruption of mucosal epithelial barriers. Although there is a return to baseline infection control coinciding with the apparent progressive recovery of hematopoietic cell populations, late susceptibility to infection in radiation-sensitive organs such as lung and kidney is known to occur. Indeed, pulmonary infections are particularly prevalent in hematopoietic cell transplant (HCT) survivors, in both adult and pediatric patient populations. Preclinical studies investigating late outcomes from localized thoracic irradiation have indicated that the mechanisms underlying pulmonary delayed effects are multifactorial, including exacerbated and persistent production of pro-inflammatory molecules and abnormal cross-talk among parenchymal and infiltrating immune and inflammatory cell populations. However, in the context of low-dose TBI, it is not clear whether the observed exacerbated response to infection remains contingent on these same mechanisms. It is possible instead, that after systemic radiation-induced injury, the susceptibility to infection may be independently related to defects in alternative organs that are revealed only through the challenge itself; indeed, we have hypothesized that this defect may be due to radiation-induced chronic effects in the structure and function of secondary lymphoid organs (SLO). In this study, we investigated the molecular and cellular alterations in SLO (i.e., spleen, mediastinal, inguinal and mesenteric lymph nodes) after TBI, and the time points when there appears to be immune competence. Furthermore, due to the high incidence of pulmonary infections in the late post-transplantation period of bone marrow transplant survivors, particularly in children, we focused on outcomes in mice irradiated as neonates, which served as a model for a pediatric population, and used the induction of adaptive immunity against influenza virus as a functional end point. We demonstrated that, in adult animals irradiated as neonates, high endothelial venule (HEV) expansion, generation of follicular helper T cells (TFH) and formation of splenic germinal centers (GC) were rapidly and, more importantly, persistently impaired in SLO, suggesting that the early-life exposure to sublethal radiation had long-lasting effects on the induction of humoral immunity. Although the neonatal TBI did not affect the overall outcome from influenza infection in the adults at the earlier time points assessed, we believe that they nonetheless contribute significantly to the increased mortality observed at subsequent late time points. Furthermore, we speculate that the detrimental and persistent impact on the induction of CD4 T- and B-cell responses in the mediastinal lymph nodes will decrease the animals' ability to respond to other aerial pathogens. Since many of these pathogens are normally cleared by antibodies, our findings provide an explanation for the susceptibility of survivors of childhood HCT to life-threatening respiratory tract infections. These findings have implications regarding the need for increased monitoring in pediatric hematopoietic cell transplant patients, since they indicate that there are ongoing and cumulative defects in SLO, which, importantly, develop during the immediate and early postirradiation period when patients may appear immunologically competent. The identification of changes in immune-related signals may offer bioindicators of progressive dysfunction, and of potential mechanisms that could be targeted so as to reduce the risk of infection from extracellular pathogens. Furthermore, these results support the potential susceptibility of the pediatric population to infection after sublethal irradiation in the context of a nuclear or radiological event.

Reduced-intensity conditioning allogeneic stem cell transplantation in pediatric patients and subsequent supportive care

PURPOSE/OBJECTIVES

To determine if children undergoing reduced-intensity conditioning allogeneic hematopoietic stem cell transplantation (RIC-AlloHSCT) have lower incidence of acute toxicities and, subsequently, require less supportive care than is required with myeloablative conditioning (MAC)-AlloHSCT. An additional purpose is to examine later outcomes by comparing 100-day transplantation-related mortality (TRM).

DESIGN

Retrospective chart and electronic medical records review.

SETTING

A pediatric care center in the northeastern United States.

SAMPLE

86 patients who underwent AlloHSCT from January 2004 through March 2008.

METHODS

Charts were retrospectively reviewed. The comparison between groups was done by t test (continuous variables) and chi-square test (categorical variables). The logistic regressions, Kaplan-Meier product-limit estimator, log rank test, and Cox proportional hazards model were used.

MAIN RESEARCH VARIABLES

Days requiring total parenteral nutrition (TPN), patient-controlled analgesia (PCA), incidence of mucositis, days with fevers, number of infections, transfers to pediatric intensive care unit (PICU), blood product infusions, and 100-day TRM, all for 30 days post-transplantation.

FINDINGS

When comparing pediatric patients undergoing RIC-AlloHSCT (n = 43) versus MAC-AlloHSCT (n = 43) in the first 30 days post-transplantation, a statistically significant decreased incidence was noted for mucositis, infections, transfers to PICU, days on TPN and PCA, and days with fever, as well as 100-day TRM.

CONCLUSIONS

For pediatric patients, RIC-AlloHSCT is associated with significantly lower acute post-transplantation toxicities and TRM than MAC-AlloHSCT.

IMPLICATIONS FOR NURSING

For nurses to correctly educate their patients and family members, and to aid nurses in anticipating patient's needs, an understanding of the potential different acute toxicities and supportive care between pediatric patients undergoing RIC- versus MAC-AlloHSCT is vital.

Perivascular, but not parenchymal, cerebral engraftment of donor cells after non-myeloablative bone marrow transplantation

Myeloablative (MyA) bone marrow transplantation (BMT) results in robust engraftment of BMT-derived cells in the central nervous system (CNS) and is neuroprotective in diverse experimental models of neurodegenerative diseases of the brain and retina. However, MyA irradiation is associated with significant morbidity and mortality and does not represent a viable therapeutic option for the elderly. Non-myeloablative (NMyA) BMT is less toxic, but it is not known if the therapeutic efficacy observed with MyA BMT is preserved. As a first step to address this important gap in knowledge, we evaluated and compared engraftment characteristics of BMT-derived monocytes/microglia using several clinically relevant NMyA pretransplant conditioning regimens in C57BL/6 mice. These included chemotherapy (fludarabine and cyclophosphamide) with or without 2 Gy irradiation, and 5.5 Gy irradiation alone. Each regimen was followed by transplantation of whole bone marrow from green fluorescent protein-expressing wild type (wt) mice. While stable hematopoietic engraftment occurred, to varying degrees, in all NMyA regimens, only 5.5 Gy irradiation resulted in significant engraftment of BMT-derived cells in the brain, where these cells were exclusively localized to perivascular, leptomeningeal, and related anatomic regions. Engraftment in retina under 5.5 Gy NMyA conditions was significantly reduced compared to MyA, but robust engraftment was identified in the optic nerve. Advancing the therapeutic applications of BMT to neurodegenerative diseases will require identification of the barrier mechanisms that MyA, but not NMyA, BMT is able to overcome.

Effects of sublethal irradiation on patterns of engraftment after murine bone marrow transplantation

Attempts to reduce the toxicity of hematopoietic stem cell transplantation have led to the use of various immunosuppressive, yet nonmyeloablative preparative regimens that often include low-dose irradiation. To determine the effects of low-dose irradiation on the dynamics of donor cell engraftment after bone marrow transplantation (BMT), we coupled standard endpoint flow cytometric analysis with in vivo longitudinal bioluminescence imaging performed throughout the early (<10 days) and late (days 10-90) post-BMT periods. To exclude the contribution of irradiation on reducing immunologic rejection, severely immune-deficient mice were chosen as recipients of allogeneic bone marrow. Flow cytometric analysis showed that sublethal doses of total body irradiation (TBI) significantly increased long-term (14 weeks) donor chimerism in the bone marrow compared with nonirradiated recipients (P < .05). Bioluminescence imaging demonstrated that the effect of TBI (P < .001) on chimerism occurred only after the first 7 days post-BMT. Flow cytometric analysis on day 3 showed no increase in the number of donor cells in irradiated bone marrow, confirming that sublethal irradiation does not enhance marrow chimerism early after transplantation. Local irradiation also significantly increased late (but not early) donor chimerism in the irradiated limb. Intrafemoral injection of donor cells provided efficient early chimerism in the injected limb, but long-term systemic donor chimerism was highest with i.v. administration (P < .05). Overall, the combination of TBI and i.v. administration of donor cells provided the highest levels of long-term donor chimerism in the marrow space. These findings suggest that the major effect of sublethal irradiation is to enhance long-term donor chimerism by inducing proliferative signals after the initial phase of homing.