Effectiveness of endothelial progenitor cell culture under microgravity for improved angiogenic potential

Abstract

Endothelial progenitor cell (EPC) transplantation is beneficial for ischemic diseases such as critical limb ischemia and ischemic heart disease. The scarcity of functional EPCs in adults is a limiting factor for EPC transplantation therapy. The quality and quantity culture (QQc) system is an effective ex vivo method for enhancing the number and angiogenic potential of EPCs. Further, microgravity environments have been shown to enhance the functional potential of stem cells. We therefore hypothesized that cells cultured with QQc under microgravity may have enhanced functionality. We cultured human peripheral blood mononuclear cells using QQc under normal (E), microgravity (MG), or microgravity followed by normal (ME) conditions and found that ME resulted in the most significant increase in CD34+ and double positive Dil-Ac-LDL-FITC-Ulex-Lectin cells, both EPC markers. Furthermore, angiogenic potential was determined by an EPC-colony forming assay. While numbers of primitive EPC-colony forming units (pEPC-CFU) did not change, numbers of definitive EPC-CFU colonies increased most under ME conditions. Gene-expression profiling also identified increases in angiogenic factors, including vascular endothelial growth factor, under MG and ME conditions. Thus, QQc along with ME conditions could be an efficient system for significantly enhancing the number and angiogenic potential of EPCs.

Conditioned media from endothelial progenitor cells cultured in simulated microgravity promote angiogenesis and bone fracture healing

“…Previously, altered gravity was identified to regulate oxygen homeostasis and HIF-1-dependent transcripts [ 30 , 31 ], and consequently refine the regenerative potentials of cells similar to hypoxic culture [ 32 ]. In our study, we for the first time found the HIF-1α/eNOS axis was activated by MG within 24 h, partially supporting the previous findings and complementing them [ 22 , 24 , 25 ]. As eNOS-derived NO are mainly regulated by angiogenic effectors or mechanical stress, which are responsible for vascular function maintenance, while iNOS induced NO are by proinflammatory cytokines that are usually involved in vascular pathologic processes [ 33 , 34 ].…”

“…Consistently, the present study also showed that short-term MG exposure significantly attenuated the proliferation of EPCs. However, it is also reported that MG exposure followed by NG culture could improve EPCs’ expansion rates and paracrine properties [ 25 ]. Therefore, MG simulation may be a powerful bioengineering tool for eliciting cell angiogenic potentials.…”

“…In recent years, space flight acquires rapid development and microgravity (MG) has been reported to improve proliferation and functions of various stem or progenitor cells [ 20 , 21 ]. Cardiovascular system is sensitive to gravity alteration [ 22 , 23 ], and repair potentials of EPCs and endothelial cells are also influenced by MG [ 24 , 25 ]. In addition, a previous study demonstrated that MG affected porcine blood-derived EPCs’ differentiation into mature endothelial cells and eNOS/NO signals in a time-dependent manner with an unclear mechanism [ 22 ].…”

“Microgravity” as a unique and useful stem cell culture environment for cell-based therapy

“…Hagiwara et al. showed an interesting application of microgravity culture in vasculogenesis and tissue regeneration [66]. They demonstrated that initial cultivation under microgravity conditions followed by cultivation under a 1G environment was shown to increase endothelial progenitor cell expansion rates and angiogenic potential to a remarkable degree.…”

A Method to Isolate CD34+ Mononuclear Cells from Canine Peripheral Blood

“…protocols for the in vitro cultivation and expansion of EPCs have been developed, these techniques still yield insufficient cell numbers and angiogenic potential (Sukmawati, & Tanaka 2015). A recent study (Hagiwara et al, 2018) demonstrated that microgravity stimulation can increase the number and angiogenic potential of CD34+ cells from peripheral blood mononuclear cells (PBMNCs).…”