Myocardial Ischemic Subject's Thymus Fat: A Novel Source of Multipotent Stromal Cells

A Network Comprised of miR-15b and miR-29a Is Involved in Vascular Endothelial Growth Factor Pathway Regulation in Thymus Adipose Tissue from Elderly Ischemic Cardiomyopathy Subjects

As the human thymus ages, it undergoes a transformation into adipose tissue known as TAT. Interestingly, in previous research, we observed elevated levels of vascular endothelial growth factor A (VEGFA) in TAT from patients with ischemic cardiomyopathy (IC), particularly in those over 70 years old. Moreover, in contrast to subcutaneous adipose tissue (SAT), TAT in elderly individuals exhibits enhanced angiogenic properties and the ability to stimulate tube formation. This makes TAT a promising candidate for angiogenic therapies and the regeneration of ischemic tissues following coronary surgery. MicroRNAs (miRNAs) have emerged as attractive therapeutic targets, especially those that regulate angiogenic processes. The study's purpose is to determine the miRNA network associated with both the VEGFA pathway regulation and the enrichment of age-linked angiogenesis in the TAT. RT-PCR was used to analyze angiogenic miRNAs and the expression levels of their predicted target genes in both TAT and SAT from elderly and middle-aged patients treated with coronary artery bypass graft surgery. miRTargetLink Human was used to search for miRNAs and their target genes. PANTHER was used to annotate the biological processes of the predicted targets. The expression of miR-15b-5p and miR-29a-3p was significantly upregulated in the TAT of elderly compared with middle-aged patients. Interestingly, VEGFA and other angiogenic targets were significantly upregulated in the TAT of elderly patients. Specifically: JAG1, PDGFC, VEGFA, FGF2, KDR, NOTCH2, FOS, PDGFRA, PDGFRB, and RHOB were upregulated, while PIK3CG and WNT7A were downregulated. Our results provide strong evidence of a miRNA/mRNA interaction network linked with age-associated TAT angiogenic enrichment in patients with IC.

Different therapeutic effects between diabetic and non-diabetic adipose stem cells in diabetic wound healing

OBJECTIVE

This study aimed to investigate how adipose tissue-derived stem cells (ASCs) from diabetic and from non-diabetic rats affect wound healing in different microenvironments.

METHOD

The two types of ASC-rich cells were distinguished by characteristic surface antigen detection. The ASC-rich cells were transplanted into the wounds of diabetic and non-diabetic rats. Wound healing rates were compared and the healing process in the wound margin sections was used to determine how ASC-rich cells affect wound healing in different microenvironments.

RESULTS

ASC density was decreased in diabetic rats. The generation time of ASC-rich cells from diabetic rats (d-ASC-rich cells) was longer than that of ASC-rich cells from non-diabetic rats. The number of pre-apoptotic cells in the third generation (passage 3) of d-ASC-rich cells was higher than that among the ASC-rich cells from non-diabetic rats. CD31 and CD34 expression was higher in d-ASC-rich cells than in ASC-rich cells from non-diabetic rats, whereas CD44 and CD105 expression was lower than that in ASC-rich cells from non-diabetic rats. Transplantation of ASC-rich cells from non-diabetic rats promoted wound healing in both non-diabetic and diabetic rats. In contrast, d-ASC-rich cells and enriched nuclear cells only promoted wound healing in non-diabetic rats. ASC-rich cell transplantation promoted greater tissue regeneration than d-ASC-rich cell transplantation.

CONCLUSION

ASC-rich cells promoted wound healing in diabetic and non-diabetic rats. ASC density was lower in the adipose tissue of diabetic rats compared with non-diabetic rats. d-ASC-rich cells did not promote wound healing in diabetic rats, suggesting that caution is warranted regarding the clinical use of diabetic adipose stem cell transplantation for the treatment of diabetic wounds.

Effect of human thymus adipose tissue-derived mesenchymal stem cells on myocardial infarction in rat model

Background and objective

Stem cell (SC) therapy exhibits promising therapeutic efficiency against cardiovascular disease. The thymus adipose tissue (TAT) is familiar to cardiac surgeons with sternotomy; however, the application of TAT in SC therapy remains unknown. We assessed the effectiveness of TAT-derived mesenchymal SCs (TAT-MSCs) in the rat myocardial infarction (MI) model.

Methods

The human TATs were obtained from the patients who underwent coronary artery bypass graft surgery. In cell studies, we performed the cumulative population doubling level assessment, fluorescence-activated cell sorting analysis, and differentiation study. In animal studies, we segregated Sprague-Dawley rats (ischemia-reperfusion model) into three (sham, vehicle, and TAT-MSC) groups based on their corresponding treatment. Trans-thoracic echocardiogram (TTE) was obtained to assess the recovery of heart function in the 1st, 4th, 8th, and 12th week after surgical manipulations. After echocardiographic study, infarcted area of the heart was measured using triphenyl tetrazolium chloride (TTC) stain.

Results

The sham group exhibited significantly better systolic and diastolic function (SDF) than the other groups did. After one week of TAT-MSC or vehicle injection, the TAT-MSC group exhibited a significant improvement in the E/E' value (25.75 ± 1.09 vs. 24.20 ± 0.91, p < 0.001) compared to the vehicle group. Although statistically insignificant, the trend of improvement in SDF was better in the TAT-MSC group than in the vehicle group. The infarcted area measured by TTC staining was 22.81 ± 6.41% and 29.95 ± 9.09% in the TAT-MSC and vehicle groups, respectively (p = 0.04).

Conclusion

Although TTE results exhibited insignificant variations in SDF, a trend with improvement in the SDF of the heart was observed in the TAT-MSC group compared to the vehicle group. The infarcted area of heart indicated significant reduction in the TAT-MSC group compared to the vehicle group as confirmed by histopathological study.

Differences in the neovascular potential of thymus versus subcutaneous adipose-derived stem cells from patients with myocardial ischaemia

Adipose tissue-derived multipotent mesenchymal cells (ASCs) participate in the information of blood vessels under hypoxic conditions. It is probable that the susceptibility of ASCs to the influence of age and ageing-associated pathologies compromises their therapeutic effectiveness depending on the adipose tissue depot. Our aim was to examine the neovascular potential under hypoxic conditions of ASCs-derived from thymic (thymASCs) and subcutaneous (subASCs) adipose tissue from 39 subjects with and without type 2 diabetes mellitus (T2DM) and of different ages who were undergoing coronary bypass surgery. We confirmed a significant decrease in the percentage of CD34⁺ CD31^- CD45^- subASCs in the cell yield of subASCs and in the survival of cultured endothelial cells in the medium conditioned by the hypox-subASCs with increasing patient age, which was not observed in thymASCs. Whereas the length of the tubules generated by hypox-subASCs tended to correlate negatively with patient age, tubule formation capacity of the hypoxic thymASCs increased significantly. Compared with subASCs, thymASCs from subjects over age 65 and without T2DM showed higher cell yield, tubule formation capacity, vascular endothelial growth factor secretion levels, and ability to promote endothelial cell survival in their conditioned medium. Deterioration in subASCs neovascular potential relative to thymASCs derived from these subjects was accompanied by higher expression levels of NOX4 mRNA and fibrotic proteins. Our results indicate that thymASCs from patients over age 65 and without T2DM have a higher angiogenic potential than those from the other patient groups, suggesting they may be a good candidate for angiogenic therapy in subjects undergoing coronary bypass surgery.

RPL13A and EEF1A1 Are Suitable Reference Genes for qPCR during Adipocyte Differentiation of Vascular Stromal Cells from Patients with Different BMI and HOMA-IR

Real-time or quantitative PCR (qPCR) is a useful technique that requires reliable reference genes for data normalization in gene expression analysis. Adipogenesis is among the biological processes suitable for this technique. The selection of adequate reference genes is essential for qPCR gene expression analysis of human Vascular Stromal Cells (hVSCs) during their differentiation into adipocytes. To the best of our knowledge, there are no studies validating reference genes for the analyses of visceral and subcutaneous adipose tissue hVSCs from subjects with different Body Mass Index (BMI) and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) index. The present study was undertaken to analyze this question. We first analyzed the stability of expression of five potential reference genes: CYC, GAPDH, RPL13A, EEF1A1, and 18S ribosomal RNA, during in vitro adipogenic differentiation, in samples from these types of patients. The expression of RPL13A and EEF1A1 was not affected by differentiation, thus being these genes the most stable candidates, while CYC, GAPDH, and 18S were not suitable for this sort of analysis. This work highlights that RPL13A and EEF1A1 are good candidates as reference genes for qPCR analysis of hVSCs differentiation into adipocytes from subjects with different BMI and HOMA-IR.