Use of p53-Silenced Endothelial Progenitor Cells to Treat Ischemia in Diabetic Peripheral Vascular Disease

Cardio-renal effect of dapagliflozin and dapagliflozin- saxagliptin combination on CD34 + ve hematopoietic stem cells (HSCs) and podocyte specific markers in type 2 diabetes (T2DM) subjects: a randomized trial

INTRODUCTION

Effects of Dapagliflozin (Dapa) and Dapagliflozin-Saxagliptin combination (Combo) was examined on peripheral blood derived CD34 + Hematopoetic Stem Cells (HSCs) as a cellular CVD biomarker. Both Dapa (a sodium-glucose co-transporter 2 or SGLT2, receptor inhibitor) and Saxagliptin (a Di-peptydl-peptidase-4 or DPP4 enzyme inhibitor) are commonly used type 2 diabetes mellitus or T2DM medications, however the benefit of using the combination has not been evaluated for cardio-renal risk assessment, in a real-life practice setting, compared to a placebo.

HYPOTHESIS

We hypothesized that Dapa will improve the outcomes when compared to placebo and the Combo maybe even more beneficial.

METHODS

This is a pilot study evaluating low dose Dapagliflozin 10 mg or low dose Dapa + low dose Saxagliptin combination. 15 subjects were enrolled in 16 weeks, double-blind, three-arm, randomized placebo matched trial, with 10mg Dapa + Saxa placebo (n = 4), 10 mg Dapa + 5 mg Saxa (n = 5) Combo, And Dapa placebo + Saxa placebo (n = 6), Placebo groups. T2DM subjects (age 30-70 yrs) with HbA1c of 7-10%, were included. CD34 + HSC number, migration, mRNA expression along with biochemistry and urine exosomes were measured. Data were collected at week 0, 8, and 16. For statistics, a mixed model regression analysis was used.

RESULTS

Significant HbA1c (p = 0.0357) reduction was noted in Combo group versus Dapa alone and Placebo. hsCRP levels (P = 0.0317) and IL-6, two important inflammatory molecules, were significantly reduced in both Dapa and Combo vs. Placebo. Leptin levels decreased significantly in both Dapa alone (p = 0.035) and Combo group(p = 0.015), vs. Placebo, however the Adiponectin levels were higher in Dapa alone group. Dapagliflozin alone reduced lipid parameters significantly particularly triglyceride (TG) when compared to placebo, with resultant visit 3 values at 99.5 ± 7.2 vs. 129 ± 12.3 and LDL/HDL ratio values were similar at 2.18 ± 0.08 vs. 2.13 ± 0.15. CD34 + cell migration improved significantly in both Dapa alone (p = 0.05) and Combo group (p = 0.05) vs. Placebo.

CONCLUSIONS

Several parameters showed significant improvement with both Dapa alone and Combo compared to placebo. However, when all outcome measures were taken into account, other than glycemic control the Combo didn't seem to offer any further benefit, over Dapa alone. Therefore, contrary to our initial hypothesis we do not believe the more expensive Dapa + Saxa combination offers any specific cardiovascular benefit compared to Dapagliflozin alone. However it is noteworthy that both Dapa and its combination with Saxagliptin showed significant improvement compared to placebo in T2DM, particularly when progenitor cell based numbers and function were analyzed and taken into account.

TRIAL REGISTRATION

The trial was registered with Clinical Trials.gov number NCT03660683, last updated 06052023.

Age-Related Choroidal Involution Is Associated with the Senescence of Endothelial Progenitor Cells in the Choroid

Background: Choroidal involution is a common feature of age-related ischemic retinopathies such as age-related macular degeneration (AMD). It is now well recognized that endothelial progenitor cells (EPCs) are essential to endothelial repair processes and in maintaining vascular integrity. However, the contribution of EPCs and the role of senescence in age-related choroidal vascular degeneration remain to be investigated. In this study, we compared the senescent phenotype of EPCs in the choroid and performed whole-genome profiling of EPCs derived from young versus old rats. Methods and Results: We isolated and compared the retinas of young (6-weeks-old) and old (16-18-month-old) rats. The thickness of the choroid and outer nuclear layer (ONL), along with local quantification of CD34+ EPCs, was performed. Compared to young rats, older rats displayed a significant reduction in choroidal and ONL thickness associated with markedly fewer choroid-localized EPCs; this was attested by lower expression of several EPC markers (CXCR4, CD34, CD117, CD133, and KLF-2). Choroid and choroid-localized EPCs displayed abundant senescence as revealed by increased β-gal and P53 expression and decreased Lamin-B1 (immunostaining and RT-qPCR). Concordantly, choroidal cells and EPCs isolated from older rats were unable to form vascular networks ex vivo. To better understand the potential mechanisms associated with the dysfunctional EPCs linked to age-related choroidal involution, we performed whole-genome profiling (mRNA and miRNA) of EPCs derived from old and young rats using next-generation sequencing (NGS); 802 genes were significantly modulated in old vs. young EPCs, corresponding to ~2% of total genes expressed. Using a bioinformatic algorithm, the KEGG pathways suggested that these genes participate in the modulation of several key signaling processes including inflammation, G protein-coupled receptors, and hematopoietic cell lineages. Moreover, we identified 13 miRNAs involved in the regulation of immune system processes, cell cycle arrest and senescence, which are significantly modulated in EPCs from old rats compared to young ones. Conclusions: Our results suggest that age-related choroidal involution is associated with fewer EPCs, albeit displaying a senescence-like phenotype. One would be tempted to propose that biological modification of native EPCs (such as with senolytic agents) could potentially provide a new strategy to preserve the vascular integrity of the aged choroid, and evade progression to degenerative maculopathies.

Marine Compound Exerts Antiaging Effect in Human Endothelial Progenitor Cells via Increasing Sirtuin1 Expression

Aging is associated with an increased risk of cardiovascular disease. Previous studies have demonstrated that compound 3 (C3), a derivative of marine compound xyloallenoide A isolated from the mangrove fungus Xylaria sp. (no. 2508), exhibited strong angiogenic activities in zebrafish. In this study, we examined the effects of C3 on the senescence of endothelial progenitor cells isolated from human peripheral blood (hEPCs). The results showed that treatment with angiotensin II (AngII) for 24 h induced hEPC senescence, as demonstrated by increased SA-β-galactosidase staining. Moreover, there is a significant decrease in telomerase activity and cellular viability in AngII-treated hEPCs. These changes in aging hEPCs were greatly recovered by C3 in a dose-dependent manner. Furthermore, C3 significantly restored the AngII-induced decrease of sirtuin type 1 (SIRT1) expression, a well-known antiaging protein. In addition, AngII increased AMP-activated protein kinase (AMPK) phosphorylation and reduced Akt phosphorylation in aging hEPCs, which were also reversed by C3. Importantly, the inhibition of C3 on hEPC senescence and AMPK/Akt dysregulation was significantly attenuated by the SIRT1-specific inhibitor nicotinoyl. These results indicated that C3 protects hEPC against AngII-induced senescence by increasing SIRT1 expression levels and balancing the AMPK/Akt signaling pathway. The inhibition of hEPCs senescence by C3 might protect EPCs against dysfunction induced by pathological factors in the elderly population. C3 may provide a novel drug candidate for the treatment of aging-related disorders.

Carvacrol Improves Vascular Function in Hypertensive Animals by Modulating Endothelial Progenitor Cells

Carvacrol, a phenolic monoterpene, has diverse biological activities, highlighting its antioxidant and antihypertensive capacity. However, there is little evidence demonstrating its influence on vascular regeneration. Therefore, we evaluated the modulation of carvacrol on endothelial repair induced by endothelial progenitor cells (EPC) in hypertension. Twelve-week-old spontaneously hypertensive rats (SHR) were treated with a vehicle, carvacrol (50 or 100 mg/kg/day), or resveratrol (10 mg/kg/day) orally for four weeks. Wistar Kyoto (WKY) rats were used as the normotensive controls. Their systolic blood pressure (SBP) was measured weekly through the tail cuff. The EPCs were isolated from the bone marrow and peripherical circulation and were quantified by flow cytometry. The functionality of the EPC was evaluated after cultivation through the quantification of colony-forming units (CFU), evaluation of eNOS, intracellular detection of reactive oxygen species (ROS), and evaluation of senescence. The superior mesenteric artery was isolated to evaluate the quantification of ROS, CD34, and CD31. Treatment with carvacrol induced EPC migration, increased CFU formation and eNOS expression and activity, and reduced ROS and senescence. In addition, carvacrol reduced vascular ROS and increased CD31 and CD34 expression. This study showed that treatment with carvacrol improved the functionality of EPC, contributing to the reduction of endothelial dysfunction.

Outcomes of integrated surgical wound treatment mode based on tibial transverse transport for diabetic foot wound

Background

Diabetic foot ulcer (DFU) is frequently difficult to heal and finally leads to amputation, resulting in high mortality rate in diabetic patients. To date, effective and optimal therapies are still lacking. This study aims to investigate the efficacy of integrated surgical wound treatment (ISWT) mode on diabetic foot wound.

Methods

From January 2021 to December 2021, 13 diabetic foot patients with Wagner grade 3 to 4 were treated with ISWT mode, which combined TTT technique with debridement, induced membrane technique, vacuum sealing drainage (VSD) technique and skin grafting technique. The time of wound healing, the skin temperature at midpoint of dorsum of affected foot (T), visual analogue scale (VAS) score and ankle-brachial index (ABI) was measured before and after surgery. CTA examination of the lower extremity arteries was performed at the end of the cortex transport to evaluate the small arteriolar formation of the lower extremity. The complications occurred in each patient were recorded.

Results

13 patients with age ranging from 45 to 66 years were followed up for 3 to 13 months. All patients healed completely without amputation being performed, no serious complications were found except for one case of nail channel infection. The mean healing time was 25.8 ± 7.8 days, with a range of 17 to 39 days. The mean time of carrying external fixation scaffolds and resuming walking was 71.8 ± 10.0 and 30.8 ± 9.1 days, with a range of 56 to 91 days and 18 to 45 days, respectively. The skin temperature at midpoint of dorsum of affected foot (T), VAS and ABI was all improved significantly at 3 months after surgery. Furthermore, CTA examination showed an increase in the number of lower extremity arteries and a thickening in the size of small arteriolar compared with those of pre-operative, and the collateral circulation of lower extremity was established and interweaved into a network.

Conclusion

Integrated surgical treatment of diabetic foot wound can achieve satisfactory clinical results.

Transplantation of Endothelial Progenitor Cells: Summary and prospect

Endothelial Progenitor Cells (EPCs) are precursor cells of endothelial cells (ECs), which can differentiate into vascular ECs, protect from endothelial dysfunction and tissue ischemia, and reduce vascular hyperplasia. Due to these functions, EPCs are used as a candidate cell source for transplantation strategies. In recent years, a great progress was achieved in EPCs biology research, and EPCs transplantation has become a research hotspot. At present, transplanted EPCs have been used to treat ischemic diseases due to their powerful vasculogenesis and beneficial paracrine effects. Although EPCs transplantation has been proved to play an important role, the clinical application of EPCs still faces many challenges. This review briefly summarized the basic characteristics of EPCs, the process of EPCs transplantation promoting the healing of ischemic tissue, and the ways to improve the efficiency of EPCs transplantation. In addition, the application of EPCs in neurological improvement, cardiovascular and respiratory diseases and the challenges and problems in clinical application of EPCs were also discussed. In the end, the application of EPCs transplantation in regenerative medicine and tissue engineering was discussed.

Role of Stromal Cell-Derived Factor-1 in Endothelial Progenitor Cell-Mediated Vascular Repair and Regeneration

Endothelial progenitor cells (EPCs) are immature endothelial cells that participate in vascular repair and postnatal neovascularization and provide a novel and promising therapy for the treatment of vascular disease. Studies in different animal models have shown that EPC mobilization through pharmacological agents and autologous EPC transplantation contribute to restoring blood supply and tissue regeneration after ischemic injury. However, these effects of the progenitor cells in clinical studies exhibit mixed results. The therapeutic efficacy of EPCs is closely associated with the number of the progenitor cells recruited into ischemic regions and their functional abilities and survival in injury tissues. In this review, we discussed the regulating role of stromal cell-derived factor-1 (also known CXCL12, SDF-1) in EPC mobilization, recruitment, homing, vascular repair and neovascularization, and analyzed the underlying machemisms of these functions. Application of SDF-1 to improve the regenerative function of EPCs following vascular injury was also discussed. SDF-1 plays a crucial role in mobilizing EPC from bone marrow into peripheral circulation, recruiting the progenitor cells to target tissue and protecting against cell death under pathological conditions; thus improve EPC regenerative capacity. SDF-1 are crucial for regulating EPC regenerative function, and provide a potential target for improve therapeutic efficacy of the progenitor cells in treatment of vascular disease.

Transplantation of Apoptosis-Resistant Endothelial Progenitor Cells Improves Renal Function in Diabetic Kidney Disease

Background

Diabetic kidney disease is associated with glomerulosclerosis and poor renal perfusion. Increased capillary formation and improved perfusion may help to halt or reverse the injury. Transplanting apoptosis‐resistant p53‐silenced endothelial progenitor cells (p53sh‐EPCs) may help improve vascularization and renal perfusion and could be more beneficial than another stem cell such as the mouse mesenchymal stromal cell (mMSC).

Methods and Results

Hyperglycemia and proteinuria were confirmed at 8 to 10 weeks in streptozotocin‐induced type1 diabetic C57Bl/6 mice, followed by transplantation of 0.3 million p53sh‐EPCs, Null‐EPCs (control), or mMSC under each kidney capsule. Urine was collected weekly for creatinine and protein levels. Blood pressure was measured by direct arterial cannulation and renal perfusion was measured by renal ultrasound. The kidneys were harvested for histology and mRNA expression. Reduction of protein/creatinine (AUC) was observed in p53sh‐EPC‐transplanted mice more than null‐EPC (1.8‐fold, P=0.03) or null‐mMSC (1.6‐fold, P=0.04, n=4) transplanted mice. Markers for angiogenesis, such as endothelial nitric oxide synthase (1.7‐fold, P=0.06), were upregulated post p53sh‐EPC transplantation compared with null EPC. However, vascular endothelial growth factor‐A expression was reduced (7‐fold, P=0.0004) in mMSC‐transplanted mice, compared with p53sh‐EPC‐transplanted mice. Isolectin‐B4 staining of kidney section showed improvement of glomerular sclerosis when p53sh‐EPC was transplanted, compared with null‐EPC or mMSC. In addition, mean and peak renal blood velocity (1.3‐fold, P=0.01, 1.4‐fold, P=0.001, respectively) were increased in p53sh‐EPC‐transplanted mice, relative to null‐EPC transplanted mice.

Conclusions

Apoptosis‐resistant p53sh EPC transplantation could be beneficial in the treatment of diabetic kidney disease by decreasing proteinuria, and improving renal perfusion and glomerular architecture.

LncRNA LINC00673 is Downregulated in Diabetic Retinopathy and Regulates the Apoptosis of Retinal Pigment Epithelial Cells via Negatively Regulating p53

BACKGROUND

Long noncoding RNA (LncRNA) LINC00673 has been proven to play critical roles in cancer biology, while its role in other diseases is unknown. It has been reported that LINC00673 could interact with p53, a critical player in diabetes and diabetic complications, suggesting that LINC00673 may also participate in diabetic retinopathy (DR). This study aimed to investigate the role of LINC00673 in DR.

METHODS

The present study included 3 groups of participants, including DR group, diabetes (DB) group, and healthy control (Control) group. Flow cytometry was utilized to determine cell apoptosis. Proteins and messenger RNAs (mRNAs) were estimated by Western blot and quantitative reverse transcription PCR (qRT-PCR), respectively.

RESULTS

LINC00673 was downregulated in plasma samples of DR patients (n=60) in comparison with the healthy controls (n=60) and negatively correlated with p53 only across DR patients but not across the healthy controls. In retinal pigment epithelial cells (RPECs), high glucose treatment downregulated LINC00673. Moreover, LINC00673 overexpression downregulated p53 and decreased RPEC apoptosis, while LINC00673 silencing upregulated p53 and increased RPEC apoptosis. In addition, p53 overexpression reduced the effects of LINC00673 overexpression.

CONCLUSION

LINC00673 is downregulated in DR patients and regulates RPEC apoptosis via negatively regulating p53.

Linagliptin, when compared to placebo, improves CD34+ve endothelial progenitor cells in type 2 diabetes subjects with chronic kidney disease taking metformin and/or insulin: a randomized controlled trial

BACKGROUND

Endothelial Progenitor cells (EPCs) has been shown to be dysfunctional in both type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD) leading to poor regeneration of endothelium and renal perfusion. EPCs have been shown to be a robust cardiovascular disease (CVD) risk indicator. Cellular mechanisms of DPP4 inhibitors such as linagliptin (LG) on CVD risk, in patients with T2DM with established CKD has not been established. Linagliptin, a DPP4 inhibitor when added to insulin, metformin or both may improve endothelial dysfunction in a diabetic kidney disease (DKD) population.

METHODS

31 subjects taking metformin and/or Insulin were enrolled in this 12 weeks, double blind, randomized placebo matched trial, with 5 mg LG compared to placebo. Type 2 diabetes subjects (30-70 years old), HbA1c of 6.5-10%, CKD Stage 1-3 were included. CD34+ cell number, migratory function, gene expression along with vascular parameters such as arterial stiffness, biochemistry, resting energy expenditure and body composition were measured. Data were collected at week 0, 6 and 12. A mixed model regression analysis was done with p value < 0.05 considered significant.

RESULTS

A double positive CD34/CD184 cell count had a statistically significant increase (p < 0.02) as determined by flow cytometry in LG group where CD184 is SDF1a cell surface receptor. Though mRNA differences in CD34+ve was more pronounced CD34- cell mRNA analysis showed increase in antioxidants (superoxide dismutase 2 or SOD2, Catalase and Glutathione Peroxidase or GPX) and prominent endothelial markers (PECAM1, VEGF-A, vWF and NOS3). Arterial stiffness measures such as augmentation Index (AI) (p < 0.04) and pulse wave analysis (PWV) were improved (reduced in stiffness) in LG group. A reduction in LDL: HDL ratio was noted in treatment group (p < 0.04). Urinary exosome protein examining podocyte health (podocalyxin, Wilms tumor and nephrin) showed reduction or improvement.

CONCLUSIONS

In DKD subjects, Linagliptin promotes an increase in CXCR4 expression on CD34 + progenitor cells with a concomitant improvement in vascular and renal parameters at 12 weeks. Trial Registration Number NCT02467478 Date of Registration: 06/08/2015.

Effects of endothelial progenitor cells transplantation on hyperlipidemia associated kidney damage in ApoE knockout mouse model

Background

Hyperlipidaemia causes kidney damage over the long term. We investigated the effect of the administration of endothelial progenitor cells (EPCs) on the progression of kidney damage in a mouse model of hyperlipidaemia.

Methods

Apolipoprotein E-knockout (ApoE^−/−) mice were treated with a high-cholesterol diet after spleen resection. Twenty-four weeks later, the mice were divided into two groups and intravenously injected with PBS or EPCs. Six weeks later, the recruitment of EPCs to the kidney was monitored by immunofluorescence. The lipid, endothelial cell, and collagen contents in the kidney were evaluated by specific immunostaining. The protein expression levels of transforming growth factor-β (TGF-β), Smad2/3, and phospho-Smad3 (p-smad3) were detected by western blot analysis.

Results

ApoE^−/− mice treated with a high-fat diet demonstrated glomerular lipid deposition, enlargement of the glomerular mesangial matrix, endothelial cell enlargement accompanied by vacuolar degeneration and an area of interstitial collagen in the kidney. Six weeks after EPC treatment, only a few EPCs were detected in the kidney tissues of ApoE^−/− mice, mainly in the kidney interstitial area. No significant differences in TGF-β, p-smad3 or smad2/3 expression were found between the PBS group and the EPC treatment group (TGF-β expression, PBS group: 1.06 ± 0.09, EPC treatment group: 1.09 ± 0.17, P = 0.787; p-smad3/smad2/3 expression: PBS group: 1.11 ± 0.41, EPC treatment group: 1.05 ± 0.33, P = 0.861).

Conclusions

Our findings demonstrate that hyperlipidaemia causes basement membrane thickening, glomerulosclerosis and the vascular degeneration of endothelial cells. The long-term administration of EPCs substantially has limited effect in the progression of kidney damage in a mouse model of hyperlipidaemia.

Antioxidant-upregulated mesenchymal stem cells reduce inflammation and improve fatty liver disease in diet-induced obesity

BACKGROUND

The incidence of obesity and diabetes is increasing rapidly. Optimal management is still elusive. Obesity associated with type 2 diabetes is known to cause adipose tissue inflammation, increase oxidative stress, and cause white fat hyperplasia and mitochondrial dysfunction. In this study, we investigated whether mitochondrial and cytosolic antioxidant-upregulated mesenchymal stem cell (MSC) delivery reduces oxidative stress and subsequently improves glucose tolerance, reduce systemic inflammation, and improves fatty liver disease in diet-induced obese (DIO) mouse models.

METHODS

Antioxidant genes Sod2 (mitochondrial) and catalase (cytosolic) or null (control) were upregulated in human adipose tissue-derived MSCs using adenoviral constructs. Modified MSCs were then delivered intraperitoneally into mice that were fed a 45% or 60% high-fat diet (HFD), and animals were followed for 4 weeks.

RESULTS

Over 4 weeks, body weight remained stable; however, we noted a significant reduction in liver fat content by histological analysis and liver triglyceride assay. Triglyceride assay (p < 0.01) confirmed reduced liver fat accumulation in animals that received either Sod2- or Cat-MSCs. There was a lower plasma level of inflammatory marker TNFα, measured in mice that were fed either 45% or 60% HFD and received Sod2- or Cat-MSCs, indicating reduced systemic inflammation. Ucp1 mRNA was upregulated approximately 100-1000-fold for omental fat and 10-100-fold for pericardial fat compared to the Null-MSC-receiving group. Pcgc1a and Prdm16 mRNA upregulation was also noted particularly for pericardial fat. Glucose tolerance showed a positive improvement trend with a lower area under the curve (AUC) values for both Sod2- and Cat-MSCs groups in comparison to control. For mice fed with 60% HFD and that received Sod2-MSCs, glucose levels were significantly lower than control (*p < 0.05) at a time point of 60 min in the glycemic curve during glucose tolerance test.

CONCLUSION

Reduction of oxidative stress post-antioxidant-upregulated MSC delivery, intraperitoneally, reduces systemic inflammation and fat accumulation in the liver. There is evidence of an increase in browning of white adipose tissue depots with concomitant improvement of glucose tolerance in a weight-independent fashion. Antioxidant-upregulated MSC delivery may be a safe yet effective therapy for obesity and prediabetes and improves related complication such as non-alcoholic fatty liver disease.

Increased expression of Sonic hedgehog restores diabetic endothelial progenitor cells and improves cardiac repair after acute myocardial infarction in diabetic mice

Damaged endothelial progenitor cells (EPCs) are associated with poor prognosis in diabetic myocardial infarction (DMI). Our previous studies revealed that an impaired Sonic hedgehog (Shh) pathway contributes to insufficient function in diabetic EPCs; however, the roles of the Shh pathway in diabetic EPC apoptosis under basal and hypoxic/ischemic conditions remain unknown. Therefore, the present study investigated whether Shh revitalized diabetic EPCs and consequently improved the deteriorative status of DMI. For this purpose, streptozotocin injection was used in male C57/BL6 mice to induce type-1 diabetes, and diabetic EPCs were isolated from the bone marrow. Apoptosis, cell function, and protein expression were investigated in EPCs in vitro. Mouse hearts were injected with adenovirus Shh-modified diabetic EPCs (DM-EPC^Shh) or control DM-EPC^Null immediately after coronary artery ligation in vivo. Cardiac function, capillary numbers, fibrosis, and cell apoptosis were then detected. First, the in vitro results demonstrated that the apoptosis of diabetic EPCs was reduced following treatment with Shh protein for 24 h, under normal or hypoxic conditions. BMI1 proto-oncogene (Bmi1), an antiapoptotic protein found in several cells, was reduced in diabetic EPCs under normal or hypoxic conditions, but was upregulated after Shh protein stimulation. When Bmi1-siRNA was administered, the antiapoptotic effect of Shh protein was significantly reversed. In addition, p53, a Bmi1-targeted gene, was demonstrated to mediate the antiapoptotic effect of the Shh/Bmi1 pathway in diabetic EPCs. The Shh/Bmi1/p53 axis also enhanced the diabetic EPC function. In vivo, Shh-modified diabetic EPCs exhibited increased EPC retention and decreased apoptosis at 3 days post-DMI. At 14 days post-DMI, these cells presented enhanced capillary density, reduced myocardial fibrosis and improved cardiac function. In conclusion, the present results demonstrated that the Shh pathway restored diabetic EPCs through the Shh/Bmi1/p53 axis, suppressed myocardial apoptosis and improved myocardial angiogenesis, thus reducing cardiac fibrosis and finally restoring myocardial repair and cardiac function in DMI. Thus, the Shh pathway may serve as a potential target for autologous cell therapy in diabetic myocardial ischemia.

Reassessing the effects of continuous positive airway pressure (CPAP) on arterial stiffness and peripheral blood derived CD34+ progenitor cells in subjects with sleep apnea

Background

Obstructive sleep apnea (OSA) is an independent risk factor for cardiovascular diseases (CVD) and vascular health. Peripheral blood-derived CD34+ progenitor cells have been used as biomarker for CVD risk and may play a similar role in OSA and CVD risk assessment. Although there are some controversial results in the literature, OSA patients may have a reduction in the number and function of CD34+ cells. The damages promoted by OSA in CD34+ cells may lead to an increase in endothelial oxidative stress and endothelial inflammation which may lead to a reduced endothelial repair capacity. In this study, we explored the effect of continuous positive airway pressure (CPAP) on peripheral blood-derived CD34+ cells and arterial stiffness (another predictor of endothelial health and CVD risk) in OSA patients.

Methods and results

Nine overweight and obese subjects without prediabetes or diabetes were recruited. Eight out of nine subjects had moderate to severe degree of OSA. CD34+ cells were isolated from peripheral blood. Number and function of these cells were monitored before and after 3 months of treatment with CPAP. No significant changes were observed in the number of CD34+ cells, CFU-Hill’s colony formation unit (CFU) count or migratory response to the chemotactic factor SDF-1a after CPAP use. However, CXCR4 mRNA expression significantly increased by 2.2-fold indicating that CPAP may have a positive effect on SDF1a receptor (CXCR4), thereby improving migration of CD34+ cells mediated by SDF1a after the 3 month period. Interestingly, in clinical arena our results showed a reduction of pulse wave velocity (an established parameter of arterial stiffness) following CPAP therapy.

Conclusions

Our findings suggest that 3-month CPAP intervention does not show statistical significant increase in CD34+ cell number and function, in mostly moderate to severe OSA subjects; however, it did demonstrate a positive trend. CPAP therapy, did help improve arterial stiffness parameter.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1251-8) contains supplementary material, which is available to authorized users.

Endothelium-Derived Factors Influence Differentiation of Fat-Derived Stromal Cells Post-Exercise in Subjects with Prediabetes

Purpose: We investigated the effect of aerobic and resistance exercise on abdominal subcutaneous fat-derived stromal cells in middle-aged subjects with prediabetes, pre- and post-exercise to establish molecular mechanisms that drive the effect of exercise. Methods: Five subjects, aged between 40 and 60 years with a body mass index between 25 and 39.9 kg/m² and with prediabetes, were enrolled in a 12-week exercise intervention program. Biophysical parameters were assessed pre- and post-exercise. Stromal cells were obtained from subcutaneous abdominal fat and cultured for 2-3 weeks. The stromal cells were then analyzed for mRNA analysis pre- and post-exercise. This was followed up with in vitro experiments where commercially obtained human fat-derived mesenchymal stromal cells (MSCs) were exposed to adipogenic media, and conditioned media from human endothelial conditioned media (ECM) cells were added to note if ECM addition altered adipogenesis. Subsequently, MSC differentiation was monitored by reverse transcription-polymerase chain reaction (RT-PCR). Results: Post-exercise, subjects' cardiometabolic parameters improved. MSC obtained at post-exercise phase, from subcutaneous fat biopsies, on RT-PCR analysis, showed upregulation of antioxidant, mitochondrial, glucose transporter, and genes associated with osteogenesis compared with pre-exercise MSC mRNA. A concomitant increase in plasma osteocalcin levels was also noted post-exercise. In vitro, MSCs exposed to adipogenic differentiation media with the addition of ECM showed a significant reduction in expression of adipogenic marker genes and instead showed upregulation of genes associated with osteogenic differentiation. Conclusions: Exercise appears to prevent adipogenic differentiation of fat-derived stromal cells and promote osteogenic differentiation, in prediabetic middle-aged subjects. Interestingly, the addition of endothelium-derived factors to adipogenic media also appears to prevent adipogenic differentiation of commercially obtained fat-derived stromal cells and promotes osteogenic differentiation. Both in vivo and in vitro findings emphasize the paracrine effect of endothelium-derived factors on fat differentiation.

p53 plays a crucial role in endothelial dysfunction associated with hyperglycemia and ischemia

p53 is a guardian of the genome that protects against carcinogenesis. There is accumulating evidence that p53 is activated with aging. Such activation has been reported to contribute to various age-associated pathologies, but its role in vascular dysfunction is largely unknown. The aim of this study was to investigate whether activation of endothelial p53 has a pathological effect in relation to endothelial function. We established endothelial p53 loss-of-function and gain-of-function models by breeding endothelial-cell specific Cre mice with floxed Trp53 or floxed Mdm2/Mdm4 mice, respectively. Then we induced diabetes by injection of streptozotocin. In the diabetic state, endothelial p53 expression was markedly up-regulated and endothelium-dependent vasodilatation was significantly impaired. Impairment of vasodilatation was significantly ameliorated in endothelial p53 knockout (EC-p53 KO) mice, and deletion of endothelial p53 also significantly enhanced the induction of angiogenesis by ischemia. Conversely, activation of endothelial p53 by deleting Mdm2/Mdm4 reduced both endothelium-dependent vasodilatation and ischemia-induced angiogenesis. Introduction of p53 into human endothelial cells up-regulated the expression of phosphatase and tensin homolog (PTEN), thereby reducing phospho-eNOS levels. Consistent with these results, the beneficial impact of endothelial p53 deletion on endothelial function was attenuated in EC-p53 KO mice with an eNOS-deficient background. These results show that endothelial p53 negatively regulates endothelium-dependent vasodilatation and ischemia-induced angiogenesis, suggesting that inhibition of endothelial p53 could be a novel therapeutic target in patients with metabolic disorders.

The synergistic effects of saxagliptin and metformin on CD34+ endothelial progenitor cells in early type 2 diabetes patients: a randomized clinical trial

AIMS

Type 2 diabetes is associated with endothelial dysfunction leading to cardiovascular disease. CD34+ endothelial Progenitor Cells (EPCs) are responsible for endothelial repair and neo-angiogenesis and can be used as a cardiovascular disease risk biomarker. This study investigated whether the addition of saxagliptin, a DPP-IV inhibitor, to metformin, may reduce cardiovascular disease risk in addition to improving glycemic control in Type 2 diabetes patients.

METHODS

In 12 week, double-blind, randomized placebo-controlled trial, 42 subjects already taking metformin 1-2 grams/day were randomized to placebo or saxagliptin 5 mg. Subjects aged 40-70 years with diabetes for < 10 years, with no known cardiovascular disease, BMI 25-39.9, HbA1C 6-9% were included. We evaluated EPCs number, function, surface markers and gene expression, in addition to arterial stiffness, blood biochemistries, resting energy expenditure, and body composition parameters. A mixed model regression to examine saxagliptin vs placebo, accounting for within-subject autocorrelation, was done with SAS (p < 0.05).

RESULTS

Although there was no significant increase in CD34+ cell number, CD31+ cells percentage increased. Saxagliptin increased migration (in response to SDF1α) with a trend of higher colony formation count. MNCs cytometry showed higher percentage of CXCR4 double positivity for both CD34 and CD31 positive cells, indicating a functional improvement. Gene expression analysis showed an upregulation in CD34+ cells for antioxidant SOD1 (p < 0.05) and a downregulation in CD34- cells for IL-6 (p < 0.01). For arterial stiffness, both augmentation index and systolic blood pressure measures went down in saxagliptin subjects (p < 0.05).

CONCLUSION

Saxagliptin, in combination with metformin, can help improve endothelial dysfunction in early diabetes before macrovascular complications appear. Trial registration Trial is registered under clinicaltrials.gov, NCT02024477.

Cell therapy for peripheral artery disease

Patients with severe peripheral artery disease (PAD) who are not candidates for revascularization have poor prognosis. Cell therapy using peripheral blood-derived or bone marrow-derived mononuclear cells, mesenchymal stem cells, or marker-specific subsets of bone marrow cells with angiogenic properties may hold promise for no-option PAD patients. Injected cells may exert beneficial actions by enhancing local angiogenesis (either through maturation of endothelial progenitors, or through secretion of angiogenic mediators), or by transducing cytoprotective signals that preserve tissue structure. Despite extensive research, robust clinical evidence supporting the use of cell therapy in patients with critical limb ischemia is lacking. Larger, well-designed placebo-controlled clinical trials did not support the positive results of smaller less rigorous studies. There is a need for high-quality clinical studies to test the effectiveness of cell therapy in PAD patients. Moreover, fundamental cell biological studies are needed to identify the optimal cell types, and to develop strategies that may enhance homing, survival and effectiveness of the injected cells.