Comparative characterization of frozen-thawed CD146+ and CD146- subsets of CD73+CD90+CD105+CD34+ human ASCs

Background

Mesenchymal stem cells are currently used to treat several diseases. Populations of putative stem cells found in the adipose tissue (ASCs) have been shown to possess particularly enhanced functionalities. Nonetheless, there is lack of evidence that evaluates the effects of cryopreservation techniques on well-defined functional ASC populations characterized by immunophenotypical repertoire.

Objective

We therefore embarked a study to compare the frozen-thawed ASC subsets: CD73+CD90+CD105+CD34+CD146-(CD34+CD146), CD73+CD90+CD105+CD34+CD146+(CD34+CD146+), and CD73+CD90+CD105+CD34+(CD34+). We assessed their characterization in different functional assays.

Method

The ASC immunophenotypical subsets-purified by a flow cytometry sorting technique-were frozen in liquid nitrogen. After a period, they were thawed to examine their differentiation ability, colony-forming units, viability, and growth rate.

Results

We confirmed that inside the primary cell culture system, the proportion of CD34+, CD34+CD146-, and CD34+CD146+ took up 80%, 62%, and 19% on average, respectively. All populations could be frozen and stored in liquid nitrogen with retention of more than 85% of cell viability and displayed comparable stemness characteristics. Most importantly, the CD34+CD146+ subpopulation displayed a higher proliferation rate than other groups.

Conclusion

Our data demonstrated that the frozen-thawed CD34+CD146+ cells might represent a promising source for autologous cellular-based therapy. These findings set the basis for ASC subpopulations-based application in future potential clinical settings.

Human umbilical cord-derived stem cell sheets improve left ventricular function in rat models of ischemic heart failure

INTRODUCTION

Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) are among the most promising cell therapy sources used to treat ischemic heart disease. Cell sheet engineering has been used to transplant stem cells and improve their therapeutic effectiveness. We aimed to evaluate the effectiveness of UC-MSC sheets in the treatment of chronic ischemic heart failure.

METHODS AND RESULTS

Flow cytometric analysis showed that UC-MSCs were positive for CD73, CD90, and CD105. UC-MSC sheets were produced from UC-MSCs using temperature-responsive culture dishes. Afterward, these sheets were transplanted onto the epicardial surface at the infarct heart in rat models of chronic ischemic heart failure. At four weeks after the transplantation, echocardiography analysis revealed that the cardiac function of the UC-MSC sheets group was significantly better than that of the suspension and myocardial infarction (MI) only groups. Furthermore, histological examinations revealed that the left ventricular remodeling was attenuated compared with the suspension and MI-only groups. In the UC-MSC slice group, the neovascular den and cell size in the infarct margin region were was significantly improved than in the suspension and MI-only groups. Also, the UC-MSC sheets inhibited the PI3K/AKT/mTOR signaling pathway in chronic ischemic heart failure.

CONCLUSIONS

UC-MSC sheets can maintain cardiac function and attenuate ventricular remodeling in chronic ischemic heart failure, indicating that this strategy would be a promising therapeutic option in the clinical scenario.

Chemical approaches to angiogenesis in development and regeneration

Vascular endothelial cells are essential building blocks of angiogenesis, which is required for normal embryonic development and tissue regeneration. In this chapter, we describe how to use transgenic zebrafish embryos expressing vascular-specific green fluorescent protein to evaluate differentiation, growth, and morphogenesis of endothelial cells. When combined with instrument automation and computational analysis, this method allows high-throughput screening for biologically active small chemical molecules that are effective in promoting angiogenesis. These molecules can be validated in mammalian endothelial cell differentiation and proliferation assays. These studies provide new reagents and therapeutic candidates for regenerative medicine studies.

Temporal assessment of vascular reactivity and functionality using MRI during postischemic proangiogenenic vascular remodeling

Postischemic angiogenesis is an important recovery mechanism. Both arteries and veins are upregulated during angiogenesis, but eventually there are more angiogenic veins than arteries in terms of number and length. It is critical to understand how the veins are modulated after ischemia and then transitioned into angiogenic vessels during the proangiogenic stage to finally serve as a restorative strength to the injured area. Using a rat model of transient focal cerebral ischemia, the hypercapnic blood oxygen level-dependent (BOLD) response was used to evaluate vascular reactivity, while the hyperoxic BOLD and tissue oxygen level-dependent (TOLD) responses were used to evaluate the vascular functionality at 1, 3, and 7days after ischemia. Vessel-like venous signals appeared on R2* maps on days 3 and 7, but not on day 1. The large hypercapnic BOLD responses on days 3 and 7 indicated that these areas have high vascular reactivity. The temporal correlation between vascular reactivity and the immunoreactivity to desmin and VEGF further indicates that the integrity of vascular reactivity is associated with the pericyte coverage as regulated by the VEGF level. Vascular functionality remained low on days 1, 3, and 7, as reflected by the small hyperoxic BOLD and large hyperoxic TOLD responses, indicating the low oxygen consumption of the ischemic tissues. These functional changes in proangiogenic veins may be critical for angiogenesis.