Directing Human Embryonic Stem Cells towards Functional Endothelial Cells Easily and without Purification

Hemangioblasts or blood islands only arise in early development thereby the sources to obtain these bi-potential cells are limited. While previous studies have isolated both lineages in vitro through the hemangioblast, derivation efficiency was rather low due to cellular damage attributed by enzyme usage and fluorescent activated cell sorting (FACS). This study focused on avoiding the use of damaging factors in the derivation of endothelial cells (ECs). Single cell H9-human embryonic stem cells (hESCs) were obtained by using a mild dissociation protocol then human embryoid body (hEB) formation was performed under hemangioblast differentiation conditions. The hEBs were subjected to a two-stage cytokine treatment procedure. Subsequent culture of the adhesive cells in day 4 hEBs gave arise to a seemingly pure population of ECs. The hESC-derived ECs were characterized by identifying signature endothelial gene and protein markers as well as testing for in vitro functionality. Furthermore, in vivo functionality was also confirmed by transplanting the cells in hindlimb ischemic murine models. We demonstrate that the genetic change required for EC derivation precedes blast colony formation. Furthermore, cell damage was prevented by abating enzyme usage and FACS, resulting in a high yield of ECs upon adhesion. Under this method, confluent cultures of ECs were obtainable 4 days after hEB formation which is significantly faster than previous protocols.

Transcription factors in the maintenance and survival of primordial follicles / 대한생식의학회지

Primordial follicles are formed prenatally in mammalian ovaries, and at birth they are fated to be activated to primary follicles, to be dormant, or to die. During the early stage of folliclulogenesis, the oocyte undergoes dynamic alterations in expression of numerous genes, which are regulated by transcription factors. Several germ-cell specific transcriptional regulators are critical for formation and maintenance of follicles. These transcriptional regulators include: Figla, Lhx8, Nobox, Sohlh1, and Sohlh2. A subset of these transcriptional regulators is mutated in women with ovarian insufficiency and infertility. Establishment of this oocyte pool is essential for fertility. This review focuses on these transcriptional regulators of female primordial follicles.

Functions of PIWI proteins in spermatogenesis / 대한생식의학회지

Recently, a significant understanding of the molecular mechanisms regulating spermatogenesis has been achieved utilizing small RNA molecules (small RNAs), including small interfering RNAs (siRNAs), microRNAs (miRNAs), and Piwi-interacting RNAs (piRNAs) which emerged as important regulators of gene expression at the post-transcriptional or translation level. piRNAs are only present in pachytene spermatocytes and round spermatids, whereas miRNAs are expressed abundantly in male germ cells throughout spermatogenesis. This review is aimed at providing a glimpse of piRNAs and their interacting family proteins such as PIWIL1, PIWIL2, and PIWIL4 in spermatogenesis.