Jung Kyu Choi

This study aims to develop an optimized method for cryopreserving the germ cells of Lissachatina fulica (L. fulica) using vitrification, as an alternative approach for conserving endangered snail species. First, we isolated several key reproductive organs, including the sperm oviduct, albumen gland, hermaphrodite gland (ovotestis), and hermaphrodite duct from L. fulica. When the ovotestis was finely chopped, numerous sperm with long tails and distinct heads were observed. The staining of sperm nuclei was confirmed using Hoechst 33342 dye. Since the hermaphrodite gland, referred to as the ovotestis, contains both male and female germ cells, we performed tissue staining on the ovotestis using hematoxylin and eosin (H&E) dye. H&E staining of the ovotestis revealed numerous oval-shaped acini containing sperm and early germ cells. Spermatocytes and spermatids were observed within distinct boundaries, with mature sperm appearing following spermatogenesis. To preserve the species of the L. fulica, we introduced vitrification technology to cryopreserve its reproductive organs. The non-vitrification group showed an average cell viability of 96.6%, while the vitrification group had 86.8% after thawing. This study presents a reliable cryopreservation protocol for L. fulica, with potential applications for other endangered snails, supporting conservation efforts to preserve genetic resources and biodiversity.

A sperm sorting chip designed to imitate the cervical environment successfully isolated high-quality sperm, with subsequent in vitro fertilization confirming embryo development.

This study aimed to isolate and freeze germ cells from the superior brown mealworm. Styrofoam diet changes were observed for 20 days to determine whether mealworms were useful insects for decomposing Styrofoam. The average weight of mealworms before the Styrofoam diet was 500 mg, which decreased to 336 mg at D20 after their diet. To preserve mealworms with excellent Styrofoam-degrading ability, we first isolated the reproductive organs of mealworms, testes, ovaries, sperms, and ovarioles. Morphologically, male and female adult brown mealworms were distinguished according to the presence or absence of a protrusion at the tip of the fifth segment of the abdomen. Sperms and ovarioles were observed in anatomically isolated testes and ovaries. We compared mechanical and enzymatic (collagenase I) methods to effectively isolate ovarioles from adult female brown mealworms. For the enzymatic method, most were torn and burst as the membrane of the ovarioles was damaged by collagenase I, unlike the mechanical method. To preserve the superior genetic resources of mealworms, we cryopreserved the ovaries of female brown mealworms using slow-freezing and vitrification. Histological analysis showed that the yolk sac was completely damaged in the ovaries after slow-freezing. However, only partial damage was achieved in the vitrification group compared to the control group (no freezing). The newly developed vitrification method with alginate-encapsulated ovarioles maintained the yolk sac in the ovarioles but was evenly distributed. These results provide basic data for reproductive studies of other useful insects and contribute to the biobanking and fertility preservation of superior mealworm germ cells and endangered insects.

Organoids are mini-organs generated through in vitro 3-dimensional culture that mimic some of the structural and physiological functions of real organs. In recent research, various organoids have been derived from pluripotent stem cells or multipotent organ-specific adult stem cells in vitro and have been used in regenerative medicine, disease modeling, precision medicine, toxicology studies, and drug discovery. However, research on reproduction-related organoids has not been comprehensive, and some limitations need to be addressed for culturing these organoids. In this review, we discuss the historical advances, major recent developments, limitations, and potential of organoid culture, including human reproductive organoids.

Cancer stem cells (CSCs) are a tumor cell subpopulation that drives tumor progression and metastasis, leading to a poor overall survival of patients. In colorectal cancer (CRC), the hyper-activation of Wnt/β-catenin signaling by a mutation of both adenomatous polyposis coli (APC) and K-Ras increases the size of the CSC population. We previously showed that CPD0857 inactivates Wnt/β-catenin signaling by promoting the ubiquitin-dependent proteasomal degradation of β-catenin and Ras proteins, thereby decreasing proliferation and increasing the apoptosis of CRC lines. CPD0857 also decreased the growth and invasiveness of CRC cells harboring mutant K-Ras resistant to EGFR mAb therapy. Here, we show that CPD0857 treatment decreases proliferation and increases the neuronal differentiation of neural progenitor cells (NPCs). CDP0857 effectively reduced the expression of CSC markers and suppressed self-renewal capacity. CPD0857 treatment also inhibited the proliferation and expression of CSC markers in D-K-Ras MT cells carrying K-Ras, APC and PI3K mutations, indicating the inhibition of PI3K/AKT signaling. Moreover, CPD0857-treated xenograft mice showed a regression of tumor growth and decreased numbers of CSCs in tumors. We conclude that CPD0857 could serve as the basis of a drug development strategy targeting CSCs activated through Wnt/β-catenin-Ras MAPK-PI3K/AKT signaling in CRCs.

Cancer stem cells (CSCs) are a tumor cell subpopulation that drives tumor progression and metastasis, leading to poor overall survival of patients. In colorectal cancer (CRC), hyper-activation of Wnt/β-catenin signaling by mutation of both Adenomatous polyposis coli (APC) and K-Ras increases the size of the CSC population. We previously showed that the CPD0857 inactivates Wnt/β-catenin signaling by promoting ubiquitin-dependent proteasomal degradation of β-catenin and Ras proteins, thereby decreasing proliferation and increasing apoptosis of CRC lines. CPD0857 also decreased growth and invasiveness of CRC cells harboring mutant K-Ras resistant to EGFR mAb therapy. Here, we show that CPD0857 treatment decreases proliferation and increases neuronal differentiation of neural progenitor cells (NPCs). CDP0857 effectively reduced expression of CSC markers and suppressed self-renewal capacity. CPD0857 treatment also inhibited proliferation and expression of CSC markers in D-K-Ras MT cells carrying K-Ras, APC and PI3K mutations, indicating inhibition of PI3K/AKT signaling. Moreover, CPD0857-treated xenograft mice showed regression of tumor growth and decreased numbers of CSCs in tumors. We conclude that CPD0857 could serve as the basis of a drug development strategy targeting CSCs activated through Wnt/β-catenin-Ras MAPK-PI3K/AKT signaling in CRCs.