Organogenesis最新文献

Extracellular matrix (ECM) materials have had remarkable success as scaffolds in tissue engineering (TE) and as therapies for tissue injury whereby the ECM microenvironment promotes constructive remodeling and tissue regeneration. ECM powder and solubilized derivatives thereof have novel applications in TE and RM afforded by the capacity of these constructs to be dynamically modulated. The powder form allows for effective incorporation and penetration of reagents; hence, ECM powder is an efficacious platform for 3D cell culture and vehicle for small molecule delivery. ECM powder offers minimally invasive therapy for tissue injury and successfully treatment for wounds refractory to first-line therapies. Comminution of ECM and fabrication of powder-derived constructs, however, may compromise the biological integrity of the ECM. The current lack of optimized fabrication protocols prevents a more extensive and effective clinical application of ECM powders. Further study on methods of ECM powder fabrication and modification is needed.

To investigate the molecular mechanism underlying taurine-stimulated proliferation and differentiation of cochlear neural stem cells (NSCs) and potential involvement of Sonic Hedgehog (Shh) pathway. The NSCs were characterized with immunofluorescence stained with nestin antibody. Cell viability was determined by MTT assay. The relative proliferation was measured by BrdU incorporation assay. The morphologic index was measured under light microscope. The relative protein level was determined by immunoblotting. Here we presented our findings that taurine stimulated proliferation and neurite outgrowth of NSCs, which was completely abolished by Shh inhibitor cyclopamine. In addition, cyclopamine antagonized taurine's effect on glutamatergic and GABAergic neuron population via suppressing expressions of Ptc-1, Smo and Gli-1. Our data supported the critical role of Shh pathway underlying the protective effect of taurine on auditory neural system.

We aimed to investigate the beneficial effect of Celastrol on inner ear stem cells and potential therapeutic value for hearing loss. The inner ear stem cells were isolated and characterized from utricular sensory epithelium of adult mice. The stemness was evaluated by sphere formation assay. The relative expressions of Atoh1, MAP-2 and Myosin VI were measured by RT-PCR and immunoblotting. The up-regulation of MAP-2 was also analysed with immunofluorescence. The in vitro neuronal excitability was interrogated by calcium oscillation. The electrophysiological property was determined by inward current recorded on patch clamp. Our results demonstrated that Celastrol treatment significantly improved the viability and proliferation of mouse inner ear stem cells, and facilitated sphere formation. Moreover, Celastrol stimulated differentiation of mouse inner ear stem cells to neuronal-like cells and enhanced neural excitability. Celastrol also enhanced neuronal-like cell identity in the inner ear stem cell derived neurons, as well as their electrophysiological function. Most notably, these effects were apparently associated with the upregulation of Atoh1 in response to Celastrol treatment. Celastrol showed beneficial effect on inner ear stem cells and held therapeutic promise against hearing loss.

Nervous system injury represent the most common injury and was unique clinical challenge. Using of growth factors (GFs) for the treatment of nervous system injury showed effectiveness in halting its process. However, simple application of GFs could not achieve high efficacy because of its rapid diffusion into body fluids and lost from the lesion site. The drug delivery systems (DDSs) construction used to deliver GFs were investigated so that they could surmount its rapid diffusion and retain at the injury site. This study summarizes commonly used DDSs for sustained release of GFs that provide neuroprotection or restoration effects for nervous system injury.

Understanding the mechanisms of controlled expansion and differentiation of basal progenitor cell populations during organogenesis is essential for developing targeted regenerative therapies. Since the cytokeratin 5-positive (K5⁺) basal epithelial cell population in the salivary gland is regulated by retinoic acid signaling, we interrogated how isoform-specific retinoic acid receptor (RAR) signaling impacts the K5⁺ cell population during salivary gland organogenesis to identify RAR isoform-specific mechanisms that could be exploited in future regenerative therapies. In this study, we utilized RAR isoform-specific inhibitors and agonists with murine submandibular salivary gland organ explants. We determined that RARα and RARγ have opposing effects on K5⁺ cell cycle progression and cell distribution. RARα negatively regulates K5⁺ cells in both whole organ explants and in isolated epithelial rudiments. In contrast, RARγ is necessary but not sufficient to positively maintain K5⁺ cells, as agonism of RARγ alone failed to significantly expand the population. Although retinoids are known to stimulate differentiation, K5 levels were not inversely correlated with differentiated ductal cytokeratins. Instead, RARα agonism and RARγ inhibition, corresponding with reduced K5, resulted in premature lumenization, as marked by prominin-1. With lineage tracing, we demonstrated that K5⁺ cells have the capacity to become prominin-1⁺ cells. We conclude that RARα and RARγ reciprocally control K5⁺ progenitor cells endogenously in the developing submandibular salivary epithelium, in a cell cycle-dependent manner, controlling lumenization independently of keratinizing differentiation. Based on these data, isoform-specific targeting RARα may be more effective than pan-RAR inhibitors for regenerative therapies that seek to expand the K5⁺ progenitor cell pool.

Summary statement: RARα and RARγ reciprocally control K5⁺ progenitor cell proliferation and distribution in the developing submandibular salivary epithelium in a cell cycle-dependent manner while regulating lumenization independently of keratinizing differentiation.

Before the secretion of hard dental tissues, tooth germs undergo several distinctive stages of development (dental lamina, bud, cap and bell). Every stage is characterized by specific proliferation patterns, which is regulated by various morphogens, growth factors and homeodomain proteins. The role of MSX homeodomain proteins in odontogenesis is rather complex. Expression domains of genes encoding for murine Msx1/2 during development are observed in tissues containing highly proliferative progenitor cells. Arrest of tooth development in Msx knockout mice can be attributed to impaired proliferation of progenitor cells. In Msx1 knockout mice, these progenitor cells start to differentiate prematurely as they strongly express cyclin-dependent kinase inhibitor p19^INK4d. p19^INK4d induces terminal differentiation of cells by blocking the cell cycle in mitogen-responsive G1 phase. Direct suppression of p19^INK4d by Msx1 protein is, therefore, important for maintaining proliferation of progenitor cells at levels required for the normal progression of tooth development. In this study, we examined the expression patterns of MSX1, MSX2 and p19^INK4d in human incisor tooth germs during the bud, cap and early bell stages of development. The distribution of expression domains of p19^INK4d throughout the investigated period indicates that p19^INK4d plays active role during human tooth development. Furthermore, comparison of expression domains of p19^INK4d with those of MSX1, MSX2 and proliferation markers Ki67, Cyclin A2 and pRb, indicates that MSX-mediated regulation of proliferation in human tooth germs might not be executed by the mechanism similar to one described in developing tooth germs of wild-type mouse.

Angiogenesis is a physiological procedure during which the new blood vessels develop from the pre-existing vessels. Uncontrolled angiogenesis is related to various diseases including cancers. Clinical inhibition of undesired angiogenesis is still under investigation. We utilized nicotinic acid, a family member of the B-vitamin niacin (vitamin B3) that has been used in the prevention and treatment of atherosclerosis or other lipid-metabolic disorders, to treat human umbilical vein endothelial cells (HUVECs) and chick chorioallantoic membrane (CAM), and investigated its influence on angiogenesis in vitro and in vivo. We found that nicotinic acid could obviously inhibit HUVEC proliferation induced by vascular endothelial growth factor. Both the in vitro and in vivo assays showed that nicotinic acid could significantly inhibit the process of angiogenesis. To further investigate the mechanism underlying the effect of nicotinic acid on angiogenesis, we found that it might function via regulating the cytoskeleton arrangements, especially the rearranging the structures of F-actin and paxillin. In summary, we discovered that nicotinic acid could obviously inhibit the process of angiogenesis by changing the angiogenesis factor expression levels and inducing the cytoskeleton rearrangement of endothelial cells.

Somatic cell nuclear transfer is a technique to create an embryo using an enucleated oocyte and a donor nucleus. Nucleus of somatic cells must be reprogrammed in order to participate in normal development within an enucleated egg. Reprogramming refers to the erasing and remodeling of cellular epigenetic marks to a lower differentiation state. Somatic nuclei must be reprogrammed by factors in the oocyte cytoplasm to a rather totipotent state since the reconstructed embryo must initiate embryo development from the one cell stage to term. In embryos reconstructed by nuclear transfer, the donor genetic material must respond to the cytoplasmic environment of the cytoplast and recapitulate this normal developmental process. Enucleation is critically important for cloning efficiency because may affect the ultrastructure of the remaining cytoplast, thus resulting in a decline or destruction of its cellular compartments. Nonetheless, the effects of in vitro culturing are yet to be fully understood. In vitro oocyte maturation can affect the abundance of specific transcripts and are likely to deplete the developmental competence. The epigenetic modifications established during cellular differentiation are a major factor determining this low efficiency as they act as epigenetic barriers restricting reprogramming of somatic nuclei. In this review we discuss some factors that could impact cell differentiation in embryo generated by nuclear transfer.

Turner's syndrome (TS) is depicted as a total or partial absence of X chromosome, and occurs in approximately 1/2200 of live born females. Generally, mosaic patients are diagnosed following karyotype analysis due to recurrent pregnancy loss, repeated in vitro fertilization (IVF) failure, and a history of malformed babies. The purpose of this case report is to show that even a selection of normal karyotype embryos can result in abnormalities for those with mosaic TS. A 32-year old patient who underwent IVF after ICSI-PGD, and was diagnosed with 45X/46XX karyotype. At the 12-week scan, one of the fetuses had an upper limb hemimelia in one arm, and feticide was applied to that fetus. The patient delivered a healthy, 2980 g female baby at the thirty-eighth week. In mosaic TS pregnancies (even those obtained by ICSI-PGD), fetal anomaly risk is high. Therefore, careful prenatal scanning is needed for these pregnancies.

Patch grafts are widely used in various kind of vascular surgeries such as detect repair or dilation of vascular stenosis. Expanded polytetrafluoroethylene (ePTFE) patches are flexible and handle well, but have shown problems with calcification as they are non-bioabsorbable and therefore permanently remain in the body. It is important to develop an alternative biocompatible patch. Silk fibroin (SF) was developed as a biocompatible material, but it lacks of the elasticity required for surgery as a patch. Polyurethane (PU) is also a well-known elastomer so this study focused on the SF and the PU blend materials with a weight ratio of 5:5 (SF/PU). To evaluate the SF/PU patch, the patches were implanted into the abdominal aortas of rats, using the ePTFE patch in the control group. Because it was more flexible the SF/PU patch was easier to implant than the ePTFE patch. At 1 week after implantation, the SF/PU patch had been infiltrated with cells and collagen fiber. The ePTFE control patch did not accumulate collagen fiber until 3 months and calcification occurred at 4 weeks. The SF/PU patch did not present any signs of calcification for 3 months. This study addressed the problems associated with using SF in isolation and showed that the SF/PU patch can be considered as a useful alternative to the ePTFE to overcome the problem of calcification.