The role of telomerase reverse transcriptase in the mitochondrial protective functions of Angiotensin-(1-7) in diabetic CD34+ cells.

Angiotensin (Ang)-(1-7) stimulates vasoprotective functions of diabetic (DB) CD34+ hematopoietic stem/progenitor cells partly by decreasing reactive oxygen species (ROS), increasing nitric oxide (NO) levels and decreasing TGFß1 secretion. Telomerase reverse transcriptase (TERT) translocates to mitochondria and regulates ROS generation. Alternative splicing of TERT results in variants α-, ß- and α-ß-TERT, which may oppose functions of full-length (FL) TERT. This study tested if the protective functions of Ang-(1-7) or TGFß1-silencing are mediated by mitoTERT and that diabetes decreases FL-TERT expression by inducing splicing. CD34+ cells were isolated from the peripheral blood mononuclear cells of nondiabetic (ND, n = 68) or DB (n = 74) subjects. NO and mitoROS levels were evaluated by flow cytometry. TERT splice variants and mitoDNA-lesions were characterized by qPCR. TRAP assay was used for telomerase activity. Decoy peptide was used to block mitochondrial translocation (mitoXTERT). TERT inhibitor or mitoXTERT prevented the effects of Ang-(1-7) on NO or mitoROS levels in DB-CD34+ cells. FL-TERT expression and telomerase activity were lower and mitoDNA-lesions were higher in DB cells compared to ND and were reversed by Ang-(1-7) or TGFß1-silencing. The prevalence of TERT splice variants, with predominant ß-TERT expression, was higher and the expression of FL-TERT was lower in DB cells (n = 25) compared to ND (n = 30). Ang-(1-7) or TGFß1-silencing decreased TERT-splicing and increased FL-TERT. Blocking of ß-splicing increased FL-TERT and protected mitoDNA in DB-cells. The findings suggest that diabetes induces TERT-splicing in CD34+ cells and that ß-TERT splice variant largely contributes to the mitoDNA oxidative damage.

ACE2 gene transfer ameliorates vasoreparative dysfunction in CD34+ cells derived from diabetic older adults.

Diabetes increases the risk for ischemic vascular diseases, which is further elevated in older adults. Bone marrow-derived hematopoietic CD34+ stem/progenitor cells have the potential of revascularization; however, diabetes attenuates vasoreparative functions. Angiotensin-converting enzyme 2 (ACE2) is the vasoprotective enzyme of renin-angiotensin system in contrast with the canonical angiotensin-converting enzyme (ACE). The present study tested the hypothesis that diabetic dysfunction is associated with ACE2/ACE imbalance in hematopoietic stem/progenitor cells (HSPCs) and that increasing ACE2 expression would restore reparative functions. Blood samples from male and female diabetic (n=71) or nondiabetic (n=62) individuals were obtained and CD34+ cells were enumerated by flow cytometry. ACE and ACE2 enzyme activities were determined in cell lysates. Lentiviral (LV) approach was used to increase the expression of soluble ACE2 protein. Cells from diabetic older adults (DB) or nondiabetic individuals (Control) were evaluated for their ability to stimulate revascularization in a mouse model of hindlimb ischemia (HLI). DB cells attenuated the recovery of blood flow to ischemic areas in nondiabetic mice compared with that observed with Control cells. Administration of DB cells modified with LV-ACE2 resulted in complete restoration of blood flow. HLI in diabetic mice resulted in poor recovery with amputations, which was not reversed by either Control or DB cells. LV-ACE2 modification of Control or DB cells resulted in blood flow recovery in diabetic mice. In vitro treatment with Ang-(1-7) modified paracrine profile in diabetic CD34+ cells. The present study suggests that vasoreparative dysfunction in CD34+ cells from diabetic older adults is associated with ACE2/ACE imbalance and that increased ACE2 expression enhances the revascularization potential.

Persistent unilateral central serous chorioretinopathy in a breastfeeding woman.

A 40-year-old woman presented with blurred vision and floaters in her right eye for the past 7 months. The patient was in the sixth month of pregnancy at onset of the ocular symptoms and had persistent ocular disturbances postpartum. Her medical and ocular history were unremarkable except for LASIK surgery. Examination revealed an uncorrected visual acuity of 20/30 and 20/20 in the right and left eye, respectively. Fundus examination showed a round, subretinal exudate involving the foveal centre. Central serous chorioretinopathy was diagnosed by fluorescein angiogram and optical coherence tomography (OCT) showing foveal neurosensory detachment and treated with intravitreal bevacizumab. At her 4-month follow-up (8 month postpartum), OCT continued to show persistent foveal subretinal fluid. Patient declined further treatment and on follow-up 1 year later, still showed a persistent neurosensory detachment on OCT testing.