Young Sca-1+ bone marrow stem cell-derived exosomes preserve visual function via the miR-150-5p/MEKK3/JNK/c-Jun pathway to reduce M1 microglial polarization.

BACKGROUND: Polarization of microglia, the resident retinal immune cells, plays important roles in mediating both injury and repair responses post-retinal ischemia-reperfusion (I/R) injury, which is one of the main pathological mechanisms behind ganglion cell apoptosis. Aging could perturb microglial balances, resulting in lowered post-I/R retinal repair. Young bone marrow (BM) stem cell antigen 1-positive (Sca-1+) cells have been demonstrated to have higher reparative capabilities post-I/R retinal injury when transplanted into old mice, where they were able to home and differentiate into retinal microglia. METHODS: Exosomes were enriched from young Sca-1+ or Sca-1- cells, and injected into the vitreous humor of old mice post-retinal I/R. Bioinformatics analyses, including miRNA sequencing, was used to analyze exosome contents, which was confirmed by RT-qPCR. Western blot was then performed to examine expression levels of inflammatory factors and underlying signaling pathway proteins, while immunofluorescence staining was used to examine the extent of pro-inflammatory M1 microglial polarization. Fluoro-Gold labelling was then utilized to identify viable ganglion cells, while H&E staining was used to examine retinal morphology post-I/R and exosome treatment. RESULTS: Sca-1+ exosome-injected mice yielded better visual functional preservation and lowered inflammatory factors, compared to Sca-1-, at days 1, 3, and 7 days post-I/R. miRNA sequencing found that Sca-1+ exosomes had higher miR-150-5p levels, compared to Sca-1- exosomes, which was confirmed by RT-qPCR. Mechanistic analysis found that miR-150-5p from Sca-1+ exosomes repressed the mitogen-activated protein kinase kinase kinase 3 (MEKK3)/JNK/c-Jun axis, leading to IL-6 and TNF-α downregulation, and subsequently reduced microglial polarization, all of which contributes to reduced ganglion cell apoptosis and preservation of proper retinal morphology. CONCLUSION: This study elucidates a potential new therapeutic approach for neuroprotection against I/R injury, via delivering miR-150-5p-enriched Sca-1+ exosomes, which targets the miR-150-5p/MEKK3/JNK/c-Jun axis, thereby serving as a cell-free remedy for treating retinal I/R injury and preserving visual functioning.

Long-term repopulation of aged bone marrow stem cells using young Sca-1 cells promotes aged heart rejuvenation.

Reduced quantity and quality of stem cells in aged individuals hinders cardiac repair and regeneration after injury. We used young bone marrow (BM) stem cell antigen 1 (Sca-1) cells to reconstitute aged BM and rejuvenate the aged heart, and examined the underlying molecular mechanisms. BM Sca-1+ or Sca-1- cells from young (2-3 months) or aged (18-19 months) GFP transgenic mice were transplanted into lethally irradiated aged mice to generate 4 groups of chimeras: young Sca-1+ , young Sca-1- , old Sca-1+ , and old Sca-1- . Four months later, expression of rejuvenation-related genes (Bmi1, Cbx8, PNUTS, Sirt1, Sirt2, Sirt6) and proteins (CDK2, CDK4) was increased along with telomerase activity and telomerase-related protein (DNA-PKcs, TRF-2) expression, whereas expression of senescence-related genes (p16INK4a , P19ARF , p27Kip1 ) and proteins (p16INK4a , p27Kip1 ) was decreased in Sca-1+ chimeric hearts, especially in the young group. Host cardiac endothelial cells (GFP- CD31+ ) but not cardiomyocytes were the primary cell type rejuvenated by young Sca-1+ cells as shown by improved proliferation, migration, and tubular formation abilities. C-X-C chemokine CXCL12 was the factor most highly expressed in homed donor BM (GFP+ ) cells isolated from young Sca-1+ chimeric hearts. Protein expression of Cxcr4, phospho-Akt, and phospho-FoxO3a in endothelial cells derived from the aged chimeric heart was increased, especially in the young Sca-1+ group. Reconstitution of aged BM with young Sca-1+ cells resulted in effective homing of functional stem cells in the aged heart. These young, regenerative stem cells promoted aged heart rejuvenation through activation of the Cxcl12/Cxcr4 pathway of cardiac endothelial cells.

Aged Human Multipotent Mesenchymal Stromal Cells Can Be Rejuvenated by Neuron-Derived Neurotrophic Factor and Improve Heart Function After Injury.

Reduced regenerative capacity of aged stem cells hampers the benefits of autologous cell therapy for cardiac regeneration. This study investigated whether neuron-derived neurotrophic factor (NDNF) could rejuvenate aged human bone marrow (hBM)- multipotent mesenchymal stromal cells (MSCs) and whether the rejuvenated hBM-MSCs could improve cardiac repair after ischemic injury. Over-expression of NDNF in old hBM-MSCs decreased cell senescence and apoptosis. Engraftment of NDNF over-expressing old hBM-MSCs into the ischemic area of mouse hearts resulted in improved cardiac function after myocardial infarction, while promoting implanted stem cell survival. Our findings suggest NDNF could be a new factor to rejuvenate aged stem cells and improve their capability to repair the aged heart after injury.

Targeted myocardial delivery of GDF11 gene rejuvenates the aged mouse heart and enhances myocardial regeneration after ischemia-reperfusion injury.

Ischemic cardiac injury is the main contributor to heart failure, and the regenerative capacity of intrinsic stem cells plays an important role in tissue repair after injury. However, stem cells in aged individuals have reduced regenerative potential and aged tissues lack the capacity to renew. Growth differentiation factor 11 (GDF11), from the activin-transforming growth factor ß superfamily, has been shown to promote stem cell activity and rejuvenation. We carried out non-invasive targeted delivery of the GDF11 gene to the heart using ultrasound-targeted microbubble destruction (UTMD) and cationic microbubble (CMB) to investigate the ability of GDF11 to rejuvenate the aged heart and improve tissue regeneration after injury. Young (3 months) and old (21 months) mice were used to evaluate the expression of GDF11 mRNA in the myocardium at baseline and after ischemia/reperfusion (I/R) and myocardial infarction. GDF11 expression decreased with age and following myocardial injury. UTMD-mediated delivery of the GDF11 plasmid to the aged heart after I/R injury effectively and selectively increased GDF11 expression in the heart, and improved cardiac function and reduced infarct size. Over-expression of GDF11 decreased senescence markers, p16 and p53, as well as the number of p16+ cells in old mouse hearts. Furthermore, increased proliferation of cardiac stem cell antigen 1 (Sca-1+) cells and increased homing of endothelial progenitor cells and angiogenesis in old ischemic hearts occurred after GDF11 over-expression. Repetitive targeted delivery of the GDF11 gene via UTMD can rejuvenate the aged mouse heart and protect it from I/R injury.

A rat model for studying neural stem cell transplantation.

AIM: The goal of this project was to develop a rat model for neural stem cell (NSC) transplantation studies in which NSCs were modified with brain-derived neurotrophic factor (BDNF) genes that may permit extensive and reliable analysis of the transplants. METHODS: NSCs were cultured and purified by limiting dilution assay in vitro and infected with recombinant retrovirus pLXSN-BDNF (BDNF-NSCs) and retrovirus pLXSN (p-NSCs). The expression of BDNF genes in transgenic and control NSC groups was measured by FQ-PCR and ELISA assays. NSCs were then transplanted into the subretinal space of normal rat retinas in four groups, which included NSCs alone, BDNF-NSCs, phosphate buffered saline (PBS) control, and normal control. Survival, migration, and differentiation of donor cells in host retinas were observed with optical coherence tomography (OCT), Heidelberg retina angiograph (HRA), and immunohistochemistry, respectively. RESULTS: The results obtained by FQ-PCR demonstrated that the copy numbers of BDNF gene templates from BDNF-NSCs were the highest among the four groups (P<0.05). Consistent with the results of FQ-PCR, BDNF protein level from the supernatant of the BDNF-NSCs group was much higher than that of the other two groups (P<0.05) as suggested by the ELISA assays. HRA and OCT showed that graft cells could successfully survive. Immunohistochemical analysis revealed that transplanted BDNF-NSCs could migrate in the host retinas and differentiate into glial cells and neurons three months after transplantation. CONCLUSION: BDNF promotes NSCs to migrate and differentiate into neural cells in the normal host retinas.

Study of brain-derived neurotrophic factor gene transgenic neural stem cells in the rat retina.

BACKGROUND: Neural stem cells (NSCs) transplantation and gene therapy have been widely investigated for treating the cerebullar and myelonic injuries, however, studies on the ophthalmology are rare. The aim of this study was to investigate the migration and differentiation of brain-derived neurotrophic factor (BDNF) gene transgenic NSCs transplanted into the normal rat retinas. METHODS: NSCs were cultured and purified in vitro and infected with recombinant retrovirus pLXSN-BDNF and pLXSN respectively, to obtain the BDNF overexpressed NSCs (BDNF-NSCs) and control cells (p-NSCs). The expression of BDNF genes in two transgenic NSCs and untreated NSCs were measured by fluorescent quantitative polymerase chain reaction (FQ-PCR) and enzyme-linked immunosorbent assay (ELISA). BDNF-NSCs and NSCs were infected with adeno-associated viruses-enhanced green fluorescent protein (AAV-EGFP) to track them in vivo and served as donor cells for transplantation into the subretinal space of normal rat retinas, phosphated buffer solution (PBS) served as pseudo transplantation for a negative control. Survival, migration, and differentiation of donor cells in host retinas were observed and analyzed with Heidelberg retina angiograph (HRA) and immunohistochemistry, respectively. RESULTS: NSCs were purified successfully by limiting dilution assay. The expression of BDNF gene in BDNF-NSCs was the highest among three groups both at mRNA level tested by FQ-PCR (P < 0.05) and at protein level measured by ELISA (P < 0.05), which showed that BDNF was overexpressed in BDNF-NSCs. The results of HRA demonstrated that graft cells could survive well and migrate into the host retinas, while the immunohistochemical analysis revealed that transplanted BDNF-NSCs differentiated into neuron more efficiently compared with the control NSCs 2 months after transplantation. CONCLUSIONS: The seed cells of NSCs highly secreting BDNF were established. BDNF can promote NSCs to migrate and differentiate into neural cells in the normal host retinas.

[Expression of connective tissue growth factor after trabeculectomy in rabbits].

OBJECTIVE: To investigate the role of connective tissue growth factor (CTGF) after trabeculectomy associated with wound healing and to identify the role of CTGF in this process. METHODS: It was a experimental study. Forty-nine rabbits were used and divided into 5 groups: normal eyes without trabeculectomy group (group A), ocular hypertension (OHT) model without trabeculectomy group (group B), OHT model with trabeculectomy group (group C), normal eyes with trabeculectomy group (group D) and normal eyes with sham operation group (group E). Group A and B were as control. CTGF mRNA was detected by RT-PCR using blebs and tissues harvested at day 2, 5, 7, and 14. Three replicates of three blebs per time point in the right eyes were collected. The expression of CTGF protein was detected by immunohistochemistry and inflammatory histopathology was inspected by HE staining using the whole eyeball harvested in the left eyes. RESULTS: Compared to group A and B, the expression of CTGF was significantly increased at day 5 after surgery (F = 19.54, P < 0.05) in group C, D, and E. The expression of CTGF mRNA in group C is significantly higher than that in group D at day 2 and 5 (t = 2.300, 5.140, P < 0.05), while group D is significantly higher than that in group E at day 2, 5, 7, and 14 (t = -2.927, -6.424, -4.176, -4.997, P < 0.05). The expression of CTGF protein in group C is significantly higher than that in group D (t = -7.147, -10.955, -9.900, -6.385, P < 0.05), and group D is higher than that in group E (F = 68.33, P < 0.05) at day 2, 5, 7, and 14, respectively. Inflammatory reaction reached peak at day 5 after surgery in group C, D, and E showing an infiltration of neutrophil, monocytes, macrophages, and the proliferation of fibroblast. CONCLUSIONS: Overexpression of CTGF in the blebs after trabeculectomy demonstrates that CTGF may play an important role in the process of wound healing. Furthermore, ocular hypertension may be involved in the upregulation of CTGF expression.

[The prevalence of primary angle-closure glaucoma and its causes in rural area of Shuangyang district in Changchun, Jilin province].

OBJECTIVE: To investigate the prevalence of primary angle-closure glaucoma (PACG) and its causes in a rural area in Changchun, China. METHODS: From the rural area of Qijiaxiang, Shuangyang district of Changchun, 1139 individuals aged 40 years and above were randomly selected for the study from September 2004 to February 2005 using Zhao Jialiang's standard. All subjects in this study underwent a preliminary screening examination including visual acuity, the peripheral depth of anterior chamber, slit lamp, tonometry and fundus. The suspects of PACG were asked to repeat the following examinations: tonometry, gonioscopy, fundus, and visual field assessment. RESULTS: 1139 of 1528 subjects were invited to participate in the study (response rate 74.5%). In those age 40 years and above, the prevalence of PACG was 1.5% in men, 3.5% in women, and 2.5% in general population, respectively. The prevalence was increased with age. The anterior chamber was significantly (P<0.01) narrower in the female group than in the male group when the peripheral depth of anterior chamber was compared. The prevalence of PACG was significantly (P<0.02) higher in subjects with positive family history than with negative family history. CONCLUSIONS: In the rural area in Shuangyang district of Changchun, the prevalence of PACG is higher than other regions surveyed in China. Sex, age, family history and the peripheral depth of anterior chamber are significant risk factors in PACG.