Human embryonic stem cells (hESC) and induced pluripotent stem cells (hiPSC) are considered attractive sources of pancreatic β cells and islet organoids. Recently, several reports presented that hESC/iPSC-derived cells enriched with specific transcription factors can form glucose-responsive insulin-secreting cells in vitro and transplantation of these cells ameliorates hyperglycemia in diabetic mice. However, the glucose-stimulated insulin-secreting capacity of these cells is lower than that of endogenous islets, suggesting the need to improve induction procedures. One of the critical problems facing in vivo maturation of hESC/iPSC-derived cells is their low survival rate after transplantation, although this rate increases when the implanted pancreatic cells are encapsulated to avoid the immune response. Several groups have also reported on the generation of hESC/iPSC-derived islet-like organoids, but development of techniques for complete islet structures with the eventual generation of vascularized constructs remains a major challenge to their application in regenerative therapies. Many issues also need to be addressed before the successful clinical application of hESC/iPSC-derived cells or islet organoids. In this review, we summarize advances in the generation of hESC/iPSC-derived pancreatic β cells or islet organoids and discuss the limitations and challenges for their successful therapeutic application in diabetes.

Cell therapy and cellular engineering begin with internalizing synthetic biomolecules and functional nanomaterials into primary cells. Conventionally, electroporation, lipofection, or viral transduction has been used; however, these are limited by their cytotoxicity, low scalability, cost, and/or preparation complexity, especially in primary cells. Thus, a universal intracellular delivery method that outperforms the existing methods must be established. Here, we present a versatile intracellular delivery platform that leverages intrinsic inertial flow developed in a T-junction microchannel with a cavity. The elongational recirculating flows exerted in the channel substantially stretch the cells, creating discontinuities on cell membranes, thereby enabling highly effective internalization of nanomaterials, such as plasmid DNA (7.9 kbp), mRNA, siRNA, quantum dots, and large nanoparticles (300 nm), into different cell types, including hard-to-transfect primary stem and immune cells. We identified that the internalization mechanism of external cargos during the cell elongation–restoration process is achieved by both passive diffusion and convection-based rapid solution exchange across the cell membrane. Using fluidic cell mechanoporation, we demonstrated a transfection yield superior to that of other state-of-the-art microfluidic platforms as well as current benchtop techniques, including lipofectamine and electroporation. In summary, the intracellular delivery platform developed in the present study enables a high delivery efficiency (up to 98%), easy operation (single-step), low material cost (<$1), high scalability (1 × 106 cells/min), minimal cell perturbation (up to 90%), and cell type/cargo insensitive delivery, providing a practical and robust approach anticipated to critically impact cell-based research.

The world has witnessed unimaginable damage from the coronavirus disease-19 (COVID-19) pandemic. Because the pandemic is growing rapidly, it is important to consider diverse treatment options to effectively treat people worldwide. Since the immune system is at the hub of the infection, it is essential to regulate the dynamic balance in order to prevent the overexaggerated immune responses that subsequently result in multiorgan damage. The use of stem cells as treatment options has gained tremendous momentum in the past decade. The revolutionary measures in science have brought to the world mesenchymal stem cells (MSCs) and MSC-derived exosomes (MSC-Exo) as therapeutic opportunities for various diseases. The MSCs and MSC-Exos have immunomodulatory functions; they can be used as therapy to strike a balance in the immune cells of patients with COVID-19. In this review, we discuss the basics of the cytokine storm in COVID-19, MSCs, and MSC-derived exosomes and the potential and stem-cell-based ongoing clinical trials for COVID-19. [BMB Reports 2020; 53(8): 400-412]

Mesenchymal stem cells (MSCs) possess a broad spectrum of therapeutic applications and have been used in clinical trials. MSCs are mainly retrieved from adult or fetal tissues. However, there are many obstacles with the use of tissue-derived MSCs, such as shortages of tissue sources, difficult and invasive retrieval methods, cell population heterogeneity, low purity, cell senescence, and loss of pluripotency and proliferative capacities over continuous passages. Therefore, other methods to obtain high-quality MSCs need to be developed to overcome the limitations of tissue-derived MSCs. Pluripotent stem cells (PSCs), including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), are considered potent sources for the derivation of MSCs. PSC-derived MSCs (PSC-MSCs) may surpass tissue-derived MSCs in proliferation capacity, immunomodulatory activity, and in vivo therapeutic applications. In this review, we will discuss basic as well as recent protocols for the production of PSC-MSCs and their in vitro and in vivo therapeutic efficacies. A better understanding of the current advances in the production of PSC-MSCs will inspire scientists to devise more efficient differentiation methods that will be a breakthrough in the clinical application of PSC-MSCs.

15-lipoxygenase is involved in the generation of specialized pro-resolving lipid mediators that play essential roles in resolution and inflammatory responses. Here, we investigated anti-inflammatory role of Alox15 in skin homeostasis. We demonstrated that knockout (KO) of Alox15 led to hair loss and disrupted the structural integrity of the dorsal skin. Alox15 KO resulted in loss of hair follicle stem cells and abnormal transition of dermal adipocytes into fibroblasts. Alox15 deficiency increased infiltration of proinflammatory macrophages and upregulated proinflammatory and necroptotic signaling in dermal adipose tissue in the dorsal skin. Lipidomic analysis revealed severe loss of resolvin D2 in the dorsal skin of Alox15 KO mice compared to wild type controls. Treatment with resolvin D2 reduced skin inflammation in Alox15 KO mice. Collectively, these results indicate that Alox15-mediated production of resolvin D2 is required to maintain skin integrity by suppressing dermal inflammation.

The role of leptin in cutaneous wound healing process has been suggested in genetically obese mouse studies. However, the molecular and cellular effects of leptin on human epidermal keratinocytes are still unclear. In this study, the whole-genome-scale microarray analysis was performed to elucidate the effect of leptin on epidermal keratinocyte functions. In the leptin-treated normal human keratinocytes (NHKs), we identified the 151 upregulated and 53 downregulated differentially expressed genes (DEGs). The gene ontology (GO) enrichment analysis with the leptin-induced DEGs suggests that leptin regulates NHKs to promote pro-inflammatory responses, extracellular matrix organization, and angiogenesis. Among the DEGs, the protein expression of IL-8, MMP-1, fibronectin, and S100A7, which play roles in which is important in the regulation of cutaneous inflammation, was confirmed in the leptin-treated NHKs. The upregulation of the leptin-induced proteins is mainly regulated by the STAT3 signaling pathway in NHKs. Among the downregulated DEGs, the protein expression of nucleosome assembly-associated centromere protein A (CENPA) and CENPM was confirmed in the leptin-treated NHKs. However, the expression of CENPA and CENPM was not coupled with those of other chromosome passenger complex like Aurora A kinase, INCENP, and survivin. In cell growth kinetics analysis, leptin had no significant effect on the cell growth curves of NHKs in the normal growth factor-enriched condition. Therefore, leptin-dependent downregulation of CENPA and CENPM in NHKs may not be directly associated with mitotic regulation during inflammation.

Rab25 can function as both a tumor suppressor and a tumor promoter across different tissues. This study sought to clarify the role of Rab25 as a tumor suppressor in skin squamous cell carcinoma (SCC). Rab25 loss was closely associated with neoplastic transition in both humans and mice. Rab25 loss was well correlated with increased cell proliferation and poor differentiation in human SCC. While Rab25 knockout (KO) in mice did not induce spontaneous tumor formation, it did significantly accelerate tumor generation and promote malignant transformation in a mouse two‐stage skin carcinogenesis model. Xenografting of a Rab25‐deficient human keratinocyte cell line, HaCaT, also elicited neoplastic transformation. Notably, Rab25 deficiency led to dysregulation of integrins β1, β4, and α6, which matched well with increased epidermal proliferation and impaired desmosome–tight junction formation. Rab25 deficiency induced impairment of integrin recycling, leading to the improper expression of integrins. In line with this, significant attenuation of integrin β1, β4, and α6 expression was identified in human SCCs where Rab25 was deficient. Collectively, these results suggest that loss of Rab25 promotes the development and neoplastic transition of SCC through dysregulation of integrin trafficking. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

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