Organogenesis最新文献

The salivary epithelium initiates as a solid mass of epithelial cells that are organized into a primary bud that undergoes morphogenesis and differentiation to yield bilayered acini consisting of interior secretory acinar cells that are surrounded by contractile myoepithelial cells in mature salivary glands. How the primary bud transitions into acini has not been previously documented. We document here that the outer epithelial cells subsequently undergo a vertical compression as they express smooth muscle α-actin and differentiate into myoepithelial cells. The outermost layer of polarized epithelial cells assemble and organize the basal deposition of basement membrane, which requires basal positioning of the polarity protein, Par-1b. Whether Par-1b is required for the vertical compression and differentiation of the myoepithelial cells is unknown. Following manipulation of Par-1b in salivary gland organ explants, Par-1b-inhibited explants showed both a reduced vertical compression of differentiating myoepithelial cells and reduced levels of smooth muscle α-actin. Rac1 knockdown and inhibition of Rac GTPase function also inhibited branching morphogenesis. Since Rac regulates cellular morphology, we investigated a contribution for Rac in myoepithelial cell differentiation. Inhibition of Rac GTPase activity showed a similar reduction in vertical compression and smooth muscle α-actin levels while decreasing the levels of Par-1b protein and altering its basal localization in the outer cells. Inhibition of ROCK, which is required for basal positioning of Par-1b, resulted in mislocalization of Par-1b and loss of vertical cellular compression, but did not significantly alter levels of smooth muscle α-actin in these cells. Overexpression of Par-1b in the presence of Rac inhibition restored basement membrane protein levels and localization. Our results indicate that the basal localization of Par-1b in the outer epithelial cells is required for myoepithelial cell compression, and Par-1b is required for myoepithelial differentiation, regardless of its localization.

Periodontal ligament stem cells (PDLSCs) are tissue-specific mesenchymal stem cells (MSCs), having an important role in regenerative therapy for teeth loss. Interleukin-7 (IL-7) is a key cytokine produced by stromal cells including MSCs, and exhibits specific roles for B and T cell development and osteoblasts differentiation of multiple myeloma. However, the effect of IL-7 on osteogenic differentiation of PDLSCs remains unclear. Therefore, in the present study we determined whether IL-7 affects the proliferation and osteogenic differentiation of PDLSCs in vitro and explored the associated signaling pathways for IL-7-mediated cell differentiation. The results demonstrated that the isolated human PDLSCs possessed MSCs features, highly expressing CD90, CD44, CD105, CD29 and CD73, and almost did not expressed CD34, CD45, CD11b, CD14 and CD117. IL-7 could not significantly affect the proliferation of PDLSCs, but it decreased their osteogenic differentiation and inhibited alkaline phosphatase (ALP) activity. The results of quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting exhibited that the expression levels of Runx-2, SP7 and osteocalcin (OCN) were significantly reduced by IL-7. Further studies indicated that IL-7 did not significantly change JNK, ERK1/2 and p38 protein production, but markedly suppressed their phosphorylation levels. These data suggest that IL-7 inhibits the osteogenic differentiation of PDLSCs probably via inactivation of mitogen-activated protein kinase (MAPK) signaling pathway.

Sex assignment in newborns depends on the anatomy of the external genitalia, despite this stage being the final in embryogenesis. According to the current view, the genital tubercle is the embryonic precursor of penis and clitoris. It originates from mesenchymal tissue, but mesenchymal cells are arranged across the embryonal body and do not have specific androgen receptors. The nature of the signal that initiates early derivation of the indifferent genital tubercle is unknown at present. The aims of this article are to improve surgical management of intersex disorders and investigate the development of the genital tubercle. Clinical examination of 114 females with various forms of DSD revealed ambiguous (bisexual) external genitalia in 73 patients, and 51 of them underwent feminizing surgery. Intersexuality (ambiguity) in 46,XY patients results from disruptors in the pathways of sex steroid hormones or receptors; in 46,XX females arises from excessive levels of androgens. Systematization of intersex disorders distinguishes the karyotype, gonadal morphology, and genital anatomy to provide a differential diagnosis and guide appropriate surgical management. Modified feminizing clitoroplasty with preservation of the dorsal and ventral neurovascular bundles to retain erogenous sensitivity was performed in females with severe virilization (Prader degree III-V). The outgrowth of the genital tubercle and the fusion of the urethral fold proceed in an ordered fashion; but in some cases of ambiguity, there was discordance due to different pathways. Speculation about the derivation of the genital tubercle have discussed with a literature review. The genital tubercle derives from the following 3 layers: the ectodermal glans of the tubercle, the mesodermal corpora cavernosa and the endodermal urogenital groove. According to the new hypothesis, during the indifferent stages, the 5 sacral somites have to recede from their segmentation and disintegrate: the sclerotomes form the pelvic bones, the fused myotomes follow with their genuine neurotomes and the angiotomes join to the corpora cavernosa of the genital tubercle. Sexual differentiation of external genitalia is final in gender embryogenesis, but surprisingly derivation of the indifferent genital tubercle from 5 somites occurs before gonadal and internal organs development.

Correct selection of an appropriate animal mode to closely mimic human extremity diseases or to exhibit desirable phenotypes of limb regeneration is the first critical step for all scientists in biomedical and regenerative researches. The commonly-used animals in limb regeneration and repairing studies, such as axolotl, mice, and rats, are discussed in the review and other models including cockroaches, dogs, and horses are also mentioned. The review weighs the general advantages, disadvantages, and precedent uses of each model in the context of limb and peripheral injury and subsequent regeneration. We hope that this review can provide the reader an overview of each model, from which to select one for their specific purpose.

Background and aims: Decellularized liver matrix (DLM) hold great potential for reconstructing functional hepatic-like tissue (HLT) based on reseeding of hepatocytes or stem cells, but the shortage of liver donors is still an obstacle for potential application. Therefore, an appropriate alternative scaffold is needed to expand the donor pool. In this study, we explored the effectiveness of decellularized spleen matrix (DSM) for culturing of bone marrow mesenchymal stem cells (BMSCs), and promoting differentiation into hepatic-like cells.

Methods: Rats' spleen were harvested for DSM preparation by freezing/thawing and perfusion procedure. Then the mesenchymal stem cells derived from rat bone marrow were reseeded into DSM for dynamic culture and hepatic differentiation by a defined induction protocol.

Results: The research found that DSM preserved a 3-dimensional porous architecture, with native extracellular matrix and vascular network which was similar to DLM. The reseeded BMSCs in DSM differentiated into functional hepatocyte-like cells, evidenced by cytomorphology change, expression of hepatic-associated genes and protein markers, glycogen storage, and indocyanine green uptake. The albumin production (2.74±0.42 vs. 2.07±0.28 pg/cell/day) and urea concentration (75.92±15.64 vs. 52.07±11.46 pg/cell/day) in DSM group were remarkably higher than tissue culture flasks (TCF) group over the same differentiation period, P< 0.05.

Conclusion: This present study demonstrated that DSM might have considerable potential in fabricating hepatic-like tissue, particularly because it can facilitate hepatic differentiation of BMSCs which exhibited higher level and more stable functions.

Dedifferentiated fat cells show great promises as a novel cell source for stem cell research. It has many advantages when used for cell-based therapeutics including abundance, pluripotency, and safety. However, there are many obstacles researchers need to overcome to make the next big move in DFAT cells research. In this review, we summarize the current main challenges in DFAT cells research including cell culture purity, phenotypic properties, and dedifferentiation mechanisms. The common methods to produce DFAT cells as well as the cell purity issue during DFAT cell production have been introduced. Current approaches to improve DFAT cell purity have been discussed. The phenotypic profile of DFAT cells have been listed and compared with other stem cells. Further studies on elucidating the underlying dedifferentiation mechanisms will dramatically advance DFAT cell research.

Insulin-Like Growth Factor 2 (IGF-2) is a peptide hormone essential for prenatal growth and development. IGF-2 exerts its mitogenic effects via Insulin-Like Growth Factor 1 Receptor (IGF-1R), and is eliminated by binding to Insulin-Like Growth Receptor 2 (IGF-2R). IGF-2 is also negatively regulated by Phosphatase and Tensin Homolog (PTEN), a phosphatase mutated in various tumors. Not much is known about the interplay between these factors during human odontogenesis. In this study, expression patterns of IGF-2, IGF-1R, IGF-2R and PTEN were analyzed by double immunofluorescence in incisor human tooth germs during the foetal period of development between the 7^th and 20^th gestational week. Throughout the investigated period, IGF-2 was mostly expressed in enamel organ, whereas mild to moderate expression of PTEN could be seen in dental papilla and parts of enamel organ. Expression of IGF-1R was ubiquitous and displayed strong intensity throughout the entire enamel organ. In contrast, expression of IGF-2R had rather erratic pattern in enamel organ and dental papilla alike. Expression patterns of IGF-2, IGF-1R, IGF-2R and PTEN in highly proliferative cervical loops, as well as in differentiating pre-ameloblasts and pre-odontoblasts of cusp tip region during the early and late bell stages when enamel organ acquires definitive shape, indicate importance of these factors in crown morphogenesis of human incisor. Taken together, our data suggest the involvement of IGF-2, IGF-1R, IGF-2R and PTEN in temporo-spatial patterning of basic cellular processes (proliferation, differentiation) during normal tooth development. They are also relevant for improving knowledge of molecular basis of human odontogenesis.

Although adipose-derived stem cells (ADSCs) have demonstrated a promising potential for the applications of cell-based therapy and regenerative medicine, excessive reactive oxygen species (ROS) are harmful to ADSCs cell survival and proliferation. Vitamin C is an important antioxidant, and is often added into culture media as an essential micronutrient. However, its roles on the proliferation of human ADSCs have not been studied. Therefore, in this study, human ADSCs were isolated, and detected by flow cytometry for the analysis of their cell surface antigens. Cell proliferation and cell cycle progression were measured with cell counting kit-8 assay and flow cytometry, respectively. Western blotting was used to detect the expression levels of cyclin E1, p53, p21, and CDK2 proteins. The effect of vitamin C pretreatment on the production of hydrogen peroxide (H₂O₂)-mediated ROS in the ADSCs was evaluated by flow cytometry. Our results indicated that vitamin C treatment significantly increased cell proliferation, and changed the cell cycle distribution of ADSCs by decreasing the percentage of G₁ phase, and concurrently increased the percentage of S and G₂/M phase. Western blot analysis indicated that vitamin C treatment up-regulated the expression levels of cyclin E1 and CDK2, but down-regulated p53 and p21 proteins expression, which contributed to cell proliferation and cell cycle progression. Vitamin C pretreatment significantly reduced the production of H₂O₂-induced ROS in the ADSCs. These findings suggest that vitamin C can promote the proliferation and cell cycle progression in the ADSCs possibly through regulation of p53-p21 signal pathway.

WKYMVm hexapeptide has been identified as a strong FPR2 agonist through a library screening of synthetic peptides. The FPR2 has been reported to play a crucial role in inflammation and angiogenic responses via stimulation of chemotaxis, migration, cell proliferation, wound healing and vessel growth. Recently, the therapeutic effects of WKYMVm have been reported in various disease models. In cutaneous wound model in diabetic mice, WKYMVm facilitated wound healing processes by stimulating the formation of capillary and arteriole and re-epithelialization. In coronary artery stenosis model, WKYMVm coating on stent promoted re-endothelialization and lowered restenosis rate. In hindlimb ischemia mouse model, intramuscular injection of WKYMVm promoted homing of exogenously transplanted endothelial colony-forming cells and neovascularization, resulting in salvaging hindlimb. Furthermore, a single injection of WKYMVm encapsulated in poly (lactide-co-glycolide) microspheres was demonstrated to be as efficient as multiple injections of WKYMVm in restoring blood flow in hindlimb ischemia model. These observations may open up promising biomedical applications of WKYMVm for tissue repairs and regenerations.