Single-cell RNA sequencing reveals a distinct profile of bone immune microenvironment and decreased osteoclast differentiation in type 2 diabetic mice

The pathogenic effects of type 2 diabetes on bone tissue are gaining attention,but the cellular and molecular mechanisms underlying osteoimmunology are still unclear in diabetes-related bone diseases.We delineated the single-cell transcriptome of bone marrow cells from both wide type and type 2 diabetes mice,which provided the first detailed global profile of bone marrow cells and revealed a distinct bone immune microenvironment at the genetic level under type 2 diabetic condition.It was observed that osteoclast activity was inhibited due to a dysre-gulated cytokine network,which ultimately led to decreased osteoclast formation and differen-tiation.In type 2 diabetes mice,a specific Cd36+cluster(cluster 18,monocytes/macrophages 2)was identified as the precursor of osteoclasts with diminished differentiation potential.AP-1 was demonstrated to be the key transcription factor in the underlying mechanism.

Mesenchymal stem/stromal cells-derived exosomes for osteoporosis treatment

Osteoporosis is a systemic bone disease,which leads to decreased bone mass and an increased risk of fragility fractures.Currently,there are many anti-resorption drugs and osteosynthesis drugs,which are effective in the treatment of osteoporosis,but their usage is limited due to their contraindications and side effects.In regenerative medicine,the unique repair ability of mesenchymal stem cells(MSCs)has been favored by researchers.The exosomes secreted by MSCs have signal transduction and molecular delivery mechanisms,which may have therapeutic effects.In this review,we describe the regulatory effects of MSCs-derived exosomes on osteoclasts,osteoblasts,and bone immunity.We aim to summarize the preclinical studies of exosome therapy in osteoporosis.Furth-ermore,we speculate that exosome therapy can be a future direction to improve bone health.

Study on blocking the leukemia immune escape after BMT by Fas-Fas ligand pathway

Background To investigate if bone marrow transplantation (BMT) with bone marrow mononuclear cells (BMMCs) transducted with murine soluble Fas gene (sFas) using adenovirus vector could block the immune escape of leukemia cells eliminate the residual leukemia cells and reduce their relapse.Methods The recombinant adenovirus vector with murine sFas, adsFas, and the control vector adEGFP were constructed using homologous recombination between two plasmids in Escherichia coli. BMT was carried out after the BMMCs were infected with Adenoviruses. The mice models of leukemia/lymphoma were constructed by inoculating female C57BL/6 mice (H-2 b) with 10 5 EL4 cells/mouse through caudal vein. Donors of bone marrow grafts were syngeneic male mice. BMMCs were infected with AdsFas or AdEGFP 24 hours before (Group D or E). The following three groups were simultaneously used: Group A, no BMMCs transplanted; Group B, transplanted with BMMCs not infected with adenoviruses; Group C, only transfusing EL4 cells, neither irradiation nor BMT. The hematopoietic reconstitution, generation of leukemia/lymphoma and the survival rate were observed in all groups after BMT. Results The adenovirus vectors were successfully constructed. The titre of virus after purification was up to 2.5×10 11 pfu/ml. Spleen indices examined 11 days after BMT were not obviously different among Group B, D and E (P>0.05), but indices in Group A were significantly lower than those in the latter three groups (P<0.01). Counts of leukocytes and platelets on +30 day showed mice were reconstituted satisfactorily in Group B and D, but very low in Group C and E. The Y-chromosomes existed 2 months after BMT and examination of bone marrow cytology showed that Group B and D were almost normal, but Group C and E had plenty of lymphoblast-like tumor cells. Tumors were obviously observed in the mice of Group C and E by histopathological examination, but the mice in Group B and D were normal. The survival rates were 0 (0/4) in Group A, 100% in Group B (6 /6) and D (16/16), 12.5% (2/16) in Group C and 6.25% (1/16) in Group E respectively. It is demonstrated that, in contrast with the control (Group EGFP), surviv al rate was significantly increased in the sFas Group (P<0.01). Conclusions The transfer of sFas gene by adenovirus changed the prognosis state of leukemia/lymphoma mice after auto-BMT. The transduction of sFas might block the effect of the immune escape of EL4 cells through FasL. These results could thus provide a new direction to find a way to treat the leukemia and its recurrence after BMT.

Bone marrow stromal cell line co-transfected with IL-2 and IL-3 genes can accelerate restoration of T-cell immunity in allo-BMT mice

Background After T-cell depleted allogeneic bone marrow transplantation, impaired immune reconstitution is a major cause of morbidity and mortality in the recipient The purpose of this study was to observe the effects of the gene-engineered bone marrow stromal cell line QXMSC1-IL-2+IL-3 on the reconstitution of T-cell immunity in allo-BMT mice Methods The bone marrow stromal cell line QXMSC1 was co-transfected with IL-2 and IL-3 genes using a Tet-on gene expression system T lymphocyte subset counts per spleen were analyzed by flow cytometry Lymphocyte proliferation response to ConA was examined to evaluate T-cell function CDR3 spectratyping techniques were performed to evaluate TCR repertoire diversity at various time points post-transplantation Results Gene engineered bone marrow stromal cell line QXMSC1-IL-2+IL-3 could express IL-2 and IL-3 (1300 ng·day -1 ·10 -6 cells and 1100 ng·day -1 ·10 -6 cells, respectively) under the control of doxycycline QXMSC1-IL-2+IL-3 in combination with allogeneic bone marrow could significantly increase the counts of CD4 + and CD8 + T cell, 1.72 and 1.27-fold respectively at week 3 compared with TCD-BMT group ( P <0.01); make CD4 +/CD8 + ratio return to normal level at week 4; enhance splenocytes mitotic response to ConA ( P <0.01), and accelerate restoration of TCR repertoire diversity in the lethally irradiated mice ( P <0.05) KH*2/5DConclusion The gene transduced stromal cell line QXMSC1-IL-2+IL-3 is able to accelerate T-cell immunity in allo-BMT mice