Combined PI3K/Akt and Smad2 Activation Promotes Corneal Endothelial Cell Proliferation

Harnessing the potential of hydrogels for advanced therapeutic applications: current achievements and future directions

The applications of hydrogels have expanded significantly due to their versatile, highly tunable properties and breakthroughs in biomaterial technologies. In this review, we cover the major achievements and the potential of hydrogels in therapeutic applications, focusing primarily on two areas: emerging cell-based therapies and promising non-cell therapeutic modalities. Within the context of cell therapy, we discuss the capacity of hydrogels to overcome the existing translational challenges faced by mainstream cell therapy paradigms, provide a detailed discussion on the advantages and principal design considerations of hydrogels for boosting the efficacy of cell therapy, as well as list specific examples of their applications in different disease scenarios. We then explore the potential of hydrogels in drug delivery, physical intervention therapies, and other non-cell therapeutic areas (e.g., bioadhesives, artificial tissues, and biosensors), emphasizing their utility beyond mere delivery vehicles. Additionally, we complement our discussion on the latest progress and challenges in the clinical application of hydrogels and outline future research directions, particularly in terms of integration with advanced biomanufacturing technologies. This review aims to present a comprehensive view and critical insights into the design and selection of hydrogels for both cell therapy and non-cell therapies, tailored to meet the therapeutic requirements of diverse diseases and situations.

Corneal Endothelial Morphology and Ocular Biometric Indexes in Premature Children With and Without Retinopathy of Prematurity

Purpose

The purpose of this study was to analyze human corneal endothelial cells (HCECs) morphology and ocular biometrics in premature (PM) children with or without retinopathy of prematurity (ROP).

Methods

Retrospective data on patient demographics, HCECs status, and ocular biometrics with at least 2 visits between 2016 and 2021 were reviewed. The main outcomes were endothelial cell density (ECD), coefficient of variation (CV), hexagonal cell ratio (HEX), central corneal thickness (CCT), axial length, anterior chamber depth, keratometry, corneal diameter, pupil diameter, and refraction status. Generalized estimating equation was used to evaluate the differences between PM no-ROP and ROP groups. We also analyzed the trend of ECD, CV, HEX, and CCT change with age between groups.

Results

The study included 173 PM patients without ROP and 139 patients with ROP. A total of 666 and 544 measurements were recorded in the PM no-ROP and ROP groups, respectively. The ROP group had higher spherical power, myopic spherical equivalent (SE), and steeper steep keratometry (K; P < 0.05). The ROP group had higher CV (P = 0.0144), lower HEX (P = 0.0012) and thicker CCT (P = 0.0035). In the HCECs parameters, the ROP group had slower ECD decrement (P < 0.0001), faster CV decrement (P = 0.0060), and faster HEX increment (P = 0.0001). A difference in corneal morphology changes between the ROP and PM no-ROP groups were prominent in patients with lower gestational age (GA) in the subgroup analysis.

Conclusions

Worse HCECs morphology and higher myopic status were initially observed in patients with prior ROP but not in PM patients with no-ROP. ECD and HCECs morphology improved with age, especially in patients with low GA.

Squishy matters - Corneal mechanobiology in health and disease

The cornea, as a dynamic and responsive tissue, constantly interacts with mechanical forces in order to maintain its structural integrity, barrier function, transparency and refractive power. Cells within the cornea sense and respond to various mechanical forces that fundamentally regulate their morphology and fate in development, homeostasis and pathophysiology. Corneal cells also dynamically regulate their extracellular matrix (ECM) with ensuing cell-ECM crosstalk as the matrix serves as a dynamic signaling reservoir providing biophysical and biochemical cues to corneal cells. Here we provide an overview of mechanotransduction signaling pathways then delve into the recent advances in corneal mechanobiology, focusing on the interplay between mechanical forces and responses of the corneal epithelial, stromal, and endothelial cells. We also identify species-specific differences in corneal biomechanics and mechanotransduction to facilitate identification of optimal animal models to study corneal wound healing, disease, and novel therapeutic interventions. Finally, we identify key knowledge gaps and therapeutic opportunities in corneal mechanobiology that are pressing for the research community to address especially pertinent within the domains of limbal stem cell deficiency, keratoconus and Fuchs' endothelial corneal dystrophy. By furthering our understanding corneal mechanobiology, we can contextualize discoveries regarding corneal diseases as well as innovative treatments for them.

Smart coating by thermo-sensitive Pluronic F-127 for enhanced corneal healing via delivery of biological macromolecule progranulin

As a leading cause of vision impairment and blindness, corneal alkali burns lead to long-term visual deterioration or even permanent visual impairment while effective treatment strategies remain a challenge. Herein, a thermo-sensitive hydrogel with the combination of multi-functional protein progranulin (PGRN), a biological macromolecule consisting of several hundred amino acids and possessing a high molecular weight, is efficiently prepared through a convenient stirring and mixing at the low temperature. The hydrogel can be easily administrated to the ocular surface contacting with the cornea, which can be immediately transformed into gel-like state due to the thermo-responsive behavior, realizing a site-specific coating to isolate further external stimulation. The smart coating not only exhibits excellent transparency and biocompatibility, but also presents a constant delivery of PGRN, creating a nutritious and supportive micro-environment for the ocular surface. The results show that the prepared functional hydrogel can efficiently suppress inflammation, accelerate re-epithelization, and intriguingly enhance axonal regeneration via modulation of multiple signaling pathways, indicating the novel designed HydrogelPGRN is a promising therapy option for serious corneal injury.

NDRG1 promotes endothelial dysfunction and hypoxia-induced pulmonary hypertension by targeting TAF15

Background

Pulmonary hypertension (PH) represents a threatening pathophysiologic state that can be induced by chronic hypoxia and is characterized by extensive vascular remodeling. However, the mechanism underlying hypoxia-induced vascular remodeling is not fully elucidated.

Methods and Results

By using quantitative polymerase chain reactions, western blotting, and immunohistochemistry, we demonstrate that the expression of N-myc downstream regulated gene-1 (NDRG1) is markedly increased in hypoxia-stimulated endothelial cells in a time-dependent manner as well as in human and rat endothelium lesions. To determine the role of NDRG1 in endothelial dysfunction, we performed loss-of-function studies using NDRG1 short hairpin RNAs and NDRG1 over-expression plasmids. In vitro, silencing NDRG1 attenuated proliferation, migration, and tube formation of human pulmonary artery endothelial cells (HPAECs) under hypoxia, while NDRG1 over-expression promoted these behaviors of HPAECs. Mechanistically, NDRG1 can directly interact with TATA-box binding protein associated factor 15 (TAF15) and promote its nuclear localization. Knockdown of TAF15 abrogated the effect of NDRG1 on the proliferation, migration and tube formation capacity of HPAECs. Bioinformatics studies found that TAF15 was involved in regulating PI3K-Akt, p53, and hypoxia-inducible factor 1 (HIF-1) signaling pathways, which have been proved to be PH-related pathways. In addition, vascular remodeling and right ventricular hypertrophy induced by hypoxia were markedly alleviated in NDRG1 knock-down rats compared with their wild-type littermates.

Conclusions

Taken together, our results indicate that hypoxia-induced upregulation of NDRG1 contributes to endothelial dysfunction through targeting TAF15, which ultimately contributes to the development of hypoxia-induced PH.

A study of the efficacy of sacubitril/valsartan plus dapagliflozin combination treatment in pulmonary arterial hypertension due to left heart disease

OBJECTIVE

To determine the efficacy of sacubitril/valsartan plus dapagliflozin in the treatment of patients with pulmonary arterial hypertension (PAH) due to left heart disease and to explore new treatment regimen for PAH due to left heart disease.

METHODS

This study is a randomized controlled trial (RCT) study of 120 patients with PAH due to left heart disease admitted to the cardiovascular department of our hospital from Dec. 2019 to Dec. 2021. The patients were randomized 1:1 to the study group and control group. All patients were given baseline treatments targeting left heart disease and symptoms of PAH. In addition to the baseline treatments, patients in the control group were given sacubitril/valsartan tablets, while patients in the study group were given sacubitril/valsartan tablets plus dapagliflozin tablets. After 6 months of treatment, parameters including left heart function and exercise tolerance, Hemodynamics (left ventricular end systolic diameter [LVSED], left ventricular end diastolic diameter [LVEDD], left ventricular ejection fraction [LVEF], 6 min walk distance (6MWD), mean pulmonary artery pressure (mPAP) and pulmonary artery systolic pressure (PASP)), vascular endothelial function (plasma endothelin (ET) -1 and nitric oxide [NO]), heart failure markers (plasma N-terminal pro-brain natriuretic peptide (NT-proBNP)], inflammatory factors (serum C reactive protein [CRP], interleukin (IL)-6, and tumor necrosis factor (TNF)-α], and adverse drug reactions (ADRs) were assessed in both groups.

RESULTS

Both groups had reduced LVESD and LVEDD, increased LVEF, and extended 6MWD after 6 months of treatment. The improvements in these parameters were significantly greater in the study group than in the control group (all P < 0.05). In addition, both the mPAP and PASP showed a decrease, and the mPAP and PASP in the study group were lower than those in the control group (p<0.05). Furthermore, both groups had decreased plasma ET-1 and NT-proBNP but increased plasma NO after 6 months of treatment. The improvements in these parameters were significantly greater in the study group than in the control group (all P < 0.05). Serum CRP, IL-6 and TNF-α levels were decreased in both groups after 6 months of treatment, and were significantly lower in the study group than in the control group (all P < 0.05). There was no significant difference in the overall incidence of ADRs between the two groups (P > 0.05).

CONCLUSION

Sacubitril/valsartan plus dapagliflozin in the treatment with PAH due to left heart disease can improve left heart function of patients by improving vascular endothelial functions and alleviating inflammation, which helps to reduce the PAH process. Therefore, this combination treatment is safe and effective in PAH due to left heart disease.

Connexins and Glucose Metabolism in Cancer

Connexins are a family of transmembrane proteins that regulate diverse cellular functions. Originally characterized for their ability to mediate direct intercellular communication through the formation of highly regulated membrane channels, their functions have been extended to the exchange of molecules with the extracellular environment, and the ability to modulate numerous channel-independent effects on processes such as motility and survival. Notably, connexins have been implicated in cancer biology for their context-dependent roles that can both promote or suppress cancer cell function. Moreover, connexins are able to mediate many aspects of cellular metabolism including the intercellular coupling of nutrients and signaling molecules. During cancer progression, changes to substrate utilization occur to support energy production and biomass accumulation. This results in metabolic plasticity that promotes cell survival and proliferation, and can impact therapeutic resistance. Significant progress has been made in our understanding of connexin and cancer biology, however, delineating the roles these multi-faceted proteins play in metabolic adaptation of cancer cells is just beginning. Glucose represents a major carbon substrate for energy production, nucleotide synthesis, carbohydrate modifications and generation of biosynthetic intermediates. While cancer cells often exhibit a dependence on glycolytic metabolism for survival, cellular reprogramming of metabolic pathways is common when blood perfusion is limited in growing tumors. These metabolic changes drive aggressive phenotypes through the acquisition of functional traits. Connections between glucose metabolism and connexin function in cancer cells and the surrounding stroma are now apparent, however much remains to be discovered regarding these relationships. This review discusses the existing evidence in this area and highlights directions for continued investigation.

Luteolin ameliorates hypoxia-induced pulmonary hypertension via regulating HIF-2α-Arg-NO axis and PI3K-AKT-eNOS-NO signaling pathway

BACKGROUND

Pulmonary hypertension (PH) is a devastating disease with poor prognosis and high mortality. Hypoxia induced pulmonary hypertension (HPH) is a persistent threat to human health, especially to people who live on high altitude plateau. Pulmonary vascular endothelial cell is involved in numerous pathophysiological processes, including in vasoconstriction, oxidative stress, cell growth and differentiation. Endothelial cells (ECs) are the first layer to be exposed to changed oxygen levels and hypoxia could lead to ECs dysfunction. Endothelial-derived nitric oxide (NO) is the most important bioactive molecule, which could regulate endothelial homeostasis. PH pathophysiology has been linked to the disruption of NO pathways.

PURPOSE

Luteolin is a kind of plant active ingredient with multiple pharmacological activities. The purpose of this study is to detect the effect of luteolin on HPH with in vivo, ex vivo and in vitro analyses and to further elucidate luteolin's pharmaceutical mechanism with NO related signaling pathway regulation.

METHODS

Hypobaric chamber was used to establish HPH animal model. Rats were intragastrically administrated luteolin for 28 days. Then hemodynamic indexes, histopathological changes, pulmonary artery endothelial function, NO content and arginase activity in lung tissue, NO related pathway proteins expression were measured to evaluate the effect of luteolin on HPH. PAECs were treated with 1% O₂ and incubated with or without luteolin. PAECs vitality, NO content in cells supernatant, and NO related pathway proteins expression were tested to reveal the protective mechanism of luteolin.

RESULTS

Luteolin decreased mean pulmonary hypertension of HPH rats, alleviated right ventricular and pulmonary vascular remodeling. Immunofluorescence staining (vWF), isolated perfused/ventilated rat lung experiment indicated that luteolin protected pulmonary vascular endothelial function of HPH rats. Luteolin increased NO content in PAECs supernatant while decreased NO level in lung tissues of HPH rats. Further, it was demonstrated that luteolin inhibited HIF-2α-Arg axis in PAECs and HPH rats. PI3K-AKT-eNOS signaling pathway was upregulated in PAECs, but which was downregulated in lung tissues of HPH rats. Pharmacological effect of luteolin was equivalent or better than sildenafil.

CONCLUSION

Luteolin ameliorated HPH in rats by protecting pulmonary vascular endothelial function via regulating HIF-2α-Arg-NO axis and PI3K-AKT-eNOS-NO signaling pathway. This study may provide a novel perspective and approach to alleviate the devastating disease of HPH.

Design of functional biomaterials as substrates for corneal endothelium tissue engineering

Corneal endothelium defects are one of the leading causes of blindness worldwide. The actual treatment is transplantation, which requires the use of human cadaveric donors, but it faces several problems, such as global shortage of donors. Therefore, new alternatives are being developed and, among them, cell therapy has gained interest in the last years due to its promising results in tissue regeneration. Nevertheless, the direct administration of cells may sometimes have limited success due to the immune response, hence requiring the combination with extracellular mimicking materials. In this review, we present different methods to obtain corneal endothelial cells from diverse cell sources such as pluripotent or multipotent stem cells. Moreover, we discuss different substrates in order to allow a correct implantation as a cell sheet and to promote an enhanced cell behavior. For this reason, natural or synthetic matrixes that mimic the native environment have been developed. These matrixes have been optimized in terms of their physicochemical properties, such as stiffness, topography, composition and transparency. To further enhance the matrixes properties, these can be tuned by incorporating certain molecules that can be delivered in a sustained manner in order to enhance biological behavior. Finally, we elucidate future directions for corneal endothelial regeneration, such as 3D printing, in order to obtain patient-specific substrates.

MicroRNAs Expression in Response to rhNGF in Epithelial Corneal Cells: Focus on Neurotrophin Signaling Pathway

PURPOSE

Nerve growth factor efficacy was demonstrated for corneal lesions treatment, and recombinant human NGF (rhNGF) was approved for neurotrophic keratitis therapy. However, NGF-induced molecular responses in cornea are still largely unknown. We analyzed microRNAs expression in human epithelial corneal cells after time-dependent rhNGF treatment.

METHODS

Nearly 700 microRNAs were analyzed by qRT-PCR. MicroRNAs showing significant expression differences were examined by DIANA-miRpath v.3.0 to identify target genes and pathways. Immunoblots were performed to preliminarily assess the strength of the in silico results.

RESULTS

Twenty-one microRNAs (miR-26a-1-3p, miR-30d-3p, miR-27b-5p, miR-146a-5p, miR-362-5p, mir-550a-5p, mir-34a-3p, mir-1227-3p, mir-27a-5p, mir-222-5p, mir-151a-5p, miR-449a, let7c-5p, miR-337-5p, mir-29b-3p, miR-200b-3p, miR-141-3p, miR-671-3p, miR-324-5p, mir-411-3p, and mir-425-3p) were significantly regulated in response to rhNGF. In silico analysis evidenced interesting target genes and pathways, including that of neurotrophin, when analyzed in depth. Almost 80 unique target genes (e.g., PI3K, AKT, MAPK, KRAS, BRAF, RhoA, Cdc42, Rac1, Bax, Bcl2, FasL) were identified as being among those most involved in neurotrophin signaling and in controlling cell proliferation, growth, and apoptosis. AKT and RhoA immunoblots demonstrated congruence with microRNA expression, providing preliminary validation of in silico data.

CONCLUSIONS

MicroRNA levels in response to rhNGF were for the first time analyzed in corneal cells. Novel insights about microRNAs, target genes, pathways modulation, and possible biological responses were provided. Importantly, given the putative role of microRNAs as biomarkers or therapeutic targets, our results make available data which might be potentially exploitable for clinical applications.

CHIR99021 balance TGFβ1 induced human corneal endothelial-to-mesenchymal transition to favor corneal endothelial cell proliferation

Corneal endothelial cells (CECs) play a major role in the maintenance of stromal hydration via the barrier and pump function for clear vision. Adult CEC cannot regenerate after injury. CECs cultured in vitro can undergo mitosis but may undergo corneal endothelial-to-mesenchymal transition (EnMT) and lose their endothelial characteristics. In this study, we examined the effects of CHIR99201 on transforming growth factor beta-1(TGFβ1)-induced EnMT in human CEC (hCECs) lines. CHIR99021 kept hCECs in the hexagonal shape and could downregulate the EnMT markers alpha-smooth muscle actin (α-SMA) and fibronectin (FN1), meanwhile maintained the hCECs function markers Na⁺/K⁺-ATPase and zonula occludens-1 (ZO-1) at levels comparable to those in the normal control. Interestingly, we found that the combination of CHIR99021 and TGFβ1 at appropriate concentrations would significantly promote the proliferation and migration of hCECs. These effects may be related to the inhibition of RhoA or Rac1, as well as the activation of Wnt and Erk pathway, with a calcium homeostasis. Our findings indicate that CHIR99021 inhibit EnMT and that the combination of CHIR99021 and TGFβ1 may provide new ideas for corneal endothelial regeneration and wound healing.

miR-151-5p alleviates corneal allograft rejection by activating PI3K/AKT signaling pathway and balancing Th17/Treg after corneal transplantation via targeting IL-2Rɑ

Background

Worldwide, corneal transplantation (CT) is the most common type of tissue replacement and the increased rate of corneal graft rejection (CGR) after CT is a critical problem. Corneal endothelium cells (CECs) are often targets of the immune response mediated by graft-attacking effector T cells. However, the molecular mechanism underlying CGR remains poorly understood.

Methods

The differentially expressed microRNAs (miRNAs) and mRNA of graft-fail corneas were measured by transcriptome sequencing (RNA-Seq). real-time quantitative polymerase chain reaction was used to measure gene expression levels. Western blot and immunofluorescence staining were used to measure protein expression levels. Kaplan-Meier survival curves were constructed to assess corneal graft survival. Hematoxylin and eosin staining was used for histopathological examination. CCK-8 and ELISA staining were used to detect cell viability and inflammatory cytokines levels, respectively. Flow cytometry was used to detect cell apoptosis and the population of Treg and Th17. Transwell migration and wound-healing assays were used to measure cell migration.

Results

We identified 453 miRNAs and 4,279 mRNAs aberrant expression in the corneas showing CGR. The differentially expressed miR-151-5p and its potential target gene [interleukin 2 receptor subunit alpha (IL-2Rɑ)] were selected from the RNA-Seq microarrays. The levels of miR-151-5p and IL-2Rɑ were respectively downregulated and upregulated in the CGR. The luciferase activity assay suggested that IL-2Rɑ is a target of miR-151-5p in 293 T cells. In addition, the miR-151-5p inhibitor, si-IL-2Rɑ, and oe-IL-2Rɑ transfection tests in CECs further confirmed that miR-151-5p downregulation and IL-2Rɑ overexpression promoted apoptosis of CECs and inhibited CEC migration, tight junction-related protein ZO-1 and Claudin-5 expression, and PI3K/AKT signaling pathway activity; however, downregulation of IL-2Rɑ abolished the inhibitor effect of miR-151-5p. Similarly, upregulation of miR-151-5p alleviated CGR via activation of the PI3K/AKT signaling pathway and balancing of Th17/Treg, and upregulation of IL-2Rɑ abolished the alleviating effect of miR-151-5p.

Conclusions

Upregulation of miR-151-5p alleviated CGR by activating the PI3K/AKT signaling pathway and balancing Th17/Treg via targeting of IL-2Rɑ, which contributes to improving the results of CT.

Improvement of an Effective Protocol for Directed Differentiation of Human Adipose Tissue-Derived Adult Mesenchymal Stem Cells to Corneal Endothelial Cells

Corneal disease affects 12.5 million individuals worldwide, with 2 million new cases each year. The standard treatment consists of a corneal transplantation from a human donor; however, the worldwide demand significantly exceeds the available supply. Lamellar endothelial keratoplasty, the replacement of only the endothelial layer of the cornea, can partially solve the problem. Progressive efforts have succeeded in expanding hCECs; however, the ability to expand hCECs is still limited, and new sources of CECs are being sought. Crucial advances have been achieved by the directed differentiation of embryonic or induced pluripotent stem cells, but these cells have disadvantages, such as the use of oncogenes, and are still difficult to establish. We aimed to transfer such knowledge to obtain hCECs from adipose tissue-derived adult mesenchymal stem cells (ADSC) by modifying four previously published procedures. We present several protocols capable of the directed differentiation of human ADSCs to hCECs. In our hands, the protocol by Ali et al. was the best adapted to such differentiation in terms of efficiency, time, and financial cost; however, the protocol by Wagoner et al. was the best for CEC marker expression. Our results broaden the type of cells of autologous extraocular origin that could be employed in the clinical setting for corneal endothelial deficiency.

Ex vivo expansion and characterization of human corneal endothelium for transplantation: a review

The corneal endothelium plays a key role in maintaining corneal transparency. Its dysfunction is currently treated with penetrating or lamellar keratoplasty. Advanced cell therapy methods seek to address the persistent global deficiency of donor corneas by enabling the renewal of the endothelial monolayer with tissue-engineered grafts. This review provides an overview of recently published literature on the preparation of endothelial grafts for transplantation derived from cadaveric corneas that have developed over the last decade (2010–2021). Factors such as the most suitable donor parameters, culture substrates and media, endothelial graft storage conditions, and transplantation methods are discussed. Despite efforts to utilize alternative cellular sources, such as induced pluripotent cells, cadaveric corneas appear to be the best source of cells for graft preparation to date. However, native endothelial cells have a limited natural proliferative capacity, and they often undergo rapid phenotype changes in ex vivo culture. This is the main reason why no culture protocol for a clinical-grade endothelial graft prepared from cadaveric corneas has been standardized so far. Currently, the most established ex vivo culture protocol involves the peel-and-digest method of cell isolation and cell culture by the dual media method, including the repeated alternation of high and low mitogenic conditions. Culture media are enriched by additional substances, such as signaling pathway (Rho-associated protein kinase, TGF-β, etc.) inhibitors, to stimulate proliferation and inhibit unwanted morphological changes, particularly the endothelial-to-mesenchymal transition. To date, this promising approach has led to the development of endothelial grafts for the first in-human clinical trial in Japan. In addition to the lack of a standard culture protocol, endothelial-specific markers are still missing to confirm the endothelial phenotype in a graft ready for clinical use. Because the corneal endothelium appears to comprise phenotypically heterogeneous populations of cells, the genomic and proteomic expression of recently proposed endothelial-specific markers, such as Cadherin-2, CD166, or SLC4A11, must be confirmed by additional studies. The preparation of endothelial grafts is still challenging today, but advances in tissue engineering and surgery over the past decade hold promise for the successful treatment of endothelial dysfunctions in more patients worldwide.

SMAD2 regulates testicular development and testosterone synthesis in Hu sheep

The SMAD protein family plays crucial roles in reproduction as a downstream target genes of the TGFβ signaling pathway. Many studies have focused on the expression change exploration of SMADs during testicular development and investigation of SMAD2 in hormone synthesis regulation. However, little attention has been given to determining the regulatory mechanism of SMADs in sheep testes. In the present study, we first detected SMAD mRNA expression levels in three-month-old (3 M), six-month-old (6 M), nine-month-old (9 M) and two-year-old (2Y) sheep testes. Different SMADs showed various expression patterns. In addition, the subcellular localization of SMAD2 was also analyzed, and Sertoli cells (SCs), Leydig cells (LCs) and spermatogonia presented mainly positive staining. Protein and nucleic acid sequence alignment showed that the SMAD2 gene was extremely homologous between various species. SMAD2 interference RNA was transfected into sheep LCs to examine the cell proliferation and hormone levels. The testosterone level was significantly decreased, and cell proliferation efficiency presented the same trend (P < 0.05). Moreover, SMAD2 downregulation promoted cell apoptosis (P < 0.05) and changed the cell cycle. In total, our results revealed that downregulating the expression of SMAD2 can effectively inhibit testosterone levels by affecting cell proliferation and apoptosis.

Discovering the Potential of Dental Pulp Stem Cells for Corneal Endothelial Cell Production: A Proof of Concept

Failure of corneal endothelium cell monolayer is the main cause leading to corneal transplantation. Autologous cell-based therapies are required to reconstruct in vitro the cell monolayer. Several strategies have been proposed using embryonic stem cells and induced pluripotent stem cells, although their use has ethical issues as well as limited clinical applications. For this purpose, we propose the use of dental pulp stem cells isolated from the third molars to form the corneal endothelium cell monolayer. We hypothesize that using dental pulp stem cells that share an embryological origin with corneal endothelial cells, as they both arise from the neural crest, may allow a direct differentiation process avoiding the use of reprogramming techniques, such as induced pluripotent stem cells. In this work, we report a two-step differentiation protocol, where dental pulp stem cells are derived into neural crest stem-like cells and, then, into corneal endothelial-like cells. Initially, for the first-step we used an adhesion culture and compared two initial cell sources: a direct formation from dental pulp stem cells with the differentiation from induced pluripotent stem cells. Results showed significantly higher levels of early stage marker AP2 for the dental pulp stem cells compared to induced pluripotent stem cells. In order to provide a better environment for neural crest stem cells generation, we performed a suspension method, which induced the formation of neurospheres. Results showed that neurosphere formation obtained the peak of neural crest stem cell markers expression after 4 days, showing overexpression of AP2, Nestin, and p75 markers, confirming the formation of neural crest stem-like cells. Furthermore, pluripotent markers Oct4, Nanog, and Sox2 were as well-upregulated in suspension culture. Neurospheres were then directly cultured in corneal endothelial conditioned medium for the second differentiation into corneal endothelial-like cells. Results showed the conversion of dental pulp stem cells into polygonal-like cells expressing higher levels of ZO-1, ATP1A1, COL4A2, and COL8A2 markers, providing a proof of the conversion into corneal endothelial-like cells. Therefore, our findings demonstrate that patient-derived dental pulp stem cells may represent an autologous cell source for corneal endothelial therapies that avoids actual transplantation limitations as well as reprogramming techniques.

Transcriptome Analysis of the Gene Expression Profiles Associated with Fungal Keratitis in Mice Based on RNA-Seq

Purpose

Fungal keratitis (FK) is an eye disease that can lead to blindness and has a high incidence worldwide. At present, there is no effective treatment for this disease. There are innate immune response mechanisms that protect against fungal infections. One example is C-type lectin receptors (CLRs), which can identify fungal invaders and trigger signal transduction pathways and cellular responses to eliminate pathogens. However, previous studies have focused mostly on single-receptor factors, and a systematic analysis of the genetic factors underlying the pathogenesis of FK has not been conducted. This study aimed to investigate the molecular mechanisms of FK in terms of genomics and to further elucidate its pathogenesis.

Methods

We performed a transcriptome analysis of a mouse model of FK using RNA sequencing to obtain the relevant gene expression profiles and to identify differentially expressed genes, signaling pathways, and regulatory networks of the key genetic factors in the pathogenesis of murine FK.

Results

Several genes that are significantly associated with FK and serve as markers of FK, such as the inflammatory cytokine genes IL1B, IL6, IL10, IL23, and TNF, were identified. The mRNA and protein expression patterns of IL-1β, IL-6, and TNF-α in the corneas of mice with FK were validated by quantitative RT-PCR and Luminex multiplex assay technology. The Wnt, cGMP–PKG, and Hippo signaling pathways were significantly enriched during fungal infection of mouse corneas.

Conclusions

Our study may help to elucidate the mechanisms of FK pathogenesis and to identify additional candidate drug targets for the treatment of FK.

PTEN Inhibition Accelerates Corneal Endothelial Wound Healing through Increased Endothelial Cell Division and Migration

Purpose

To investigate the role of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) in the regulation of corneal endothelial cell (CECs) focusing on proliferation and migration, and to further evaluate the application of PTEN inhibitors in the treatment of corneal endothelial dysfunction in a rat model.

Methods

Expression of PTEN in human and rat corneal endothelium was determined by immunocytochemistry, western blotting, and ELISA. A small molecular inhibitor of PTEN, bpV(pic), was applied in the culture of human CEC cell line B4G12 and organ-cultured rat cornea in the presence of transforming growth factor beta 2 (TGF-β2). Cell cycle status was detected by flow cytometry and BrdU staining. Subcellular localization for endogenous p27Kip1 was detected by immunocytochemistry and western blotting. Moreover, exogenous transfected YFP-p27Kip1 was observed under a fluorescent microscope. Cell migration was examined with a wound scratch model and transwell invasion assay. Finally, bpV(pic) was intracamerally injected in a rat corneal endothelial injury model. The wound healing process was evaluated by slit lamp biomicroscopy, optical coherence tomography, histological and scanning electron microscope examination.

Results

The expression of PTEN in human corneal endothelium was higher compared with rat, which we speculate was mostly responsible for the relatively less proliferation capacity of human CEC than rat. PTEN inhibition by bpV(pic) could reverse TGF-β2-induced CEC G1-arrest by alleviating p27Kip1 nuclear accumulation and decreasing total p27Kip1 expression. In addition, bpV(pic) promoted CEC migration, which acted synergistically with TGF-β2. Finally, intracameral injection of bpV(pic) could promote corneal endothelial wound healing in a rat model.

Conclusions

Our study provided experimental basis for the development of therapeutic agent targeting on PTEN for the treatment of corneal endothelial dysfunction.

Insulin, but Not Metformin, Supports Wound Healing Process in Rats with Streptozotocin-Induced Diabetes

PURPOSE

Optimal glycemic control is crucial for proper wound healing in patients with diabetes. However, it is not clear whether other antidiabetic drugs support wound healing in mechanisms different from the normalization of blood glucose control. We assessed the effect of insulin and metformin administration on the wound healing process in rats with streptozotocin-induced diabetes.

METHODS

The study was conducted on 200 male Wistar rats with streptozotocin-induced diabetes. In the last phase of the study, 45 rats, with the most stable glucose levels in the range of 350-500 mg/dL, were divided into three groups: group I received human non-protamine insulin subcutaneously (5 IU/kg body mass) once a day, group II received metformin intragastrically (500 mg/kg b.m.), and group III (control) was given saline subcutaneously. After 14 days of antidiabetic treatment, a 2 cm × 2 cm thin layer of skin was cut from each rat's dorsum and a 4 cm disk with a hole in its center was sewn in to stabilize the skin and standardize the healing process. The wound healing process was followed up for 9 days, with assessment every 3 days. Biopsy samples were subjected to hematoxylin and eosin staining and immunohistochemical assays.

RESULTS

Analysis of variance revealed significant influence of treatment type (insulin, control, or metformin) on the relative change in wound surface area. The wound healing process in rats treated with insulin was more effective than in the metformin and control groups. Wound tissue samples taken from the insulin-treated animals presented significantly lower levels of inflammatory infiltration. Immunohistochemical assessment showed the greatest density of centers of proliferation Ki-67 in insulin-treated animals.

CONCLUSION

These results suggest that an insulin-based treatment is more beneficial than metformin, in terms of accelerating the wound healing process in an animal model of streptozocin-induced diabetes.

Corneal endothelium tissue engineering: An evolution of signaling molecules, cells, and scaffolds toward 3D bioprinting and cell sheets

Cornea is an avascular and transparent tissue that focuses light on retina. Cornea is supported by the corneal-endothelial layer through regulation of hydration homeostasis. Restoring vision in patients afflicted with corneal endothelium dysfunction-mediated blindness most often requires corneal transplantation (CT), which faces considerable constrictions due to donor limitations. An emerging alternative to CT is corneal endothelium tissue engineering (CETE), which involves utilizing scaffold-based methods and scaffold-free strategies. The innovative scaffold-free method is cell sheet engineering, which typically generates cell layers surrounded by an intact extracellular matrix, exhibiting tunable release from the stimuli-responsive surface. In some studies, scaffold-based or scaffold-free technologies have been reported to achieve promising outcomes. However, yet some issues exist in translating CETE from bench to clinical practice. In this review, we compare different corneal endothelium regeneration methods and elaborate on the application of multiple cell types (stem cells, corneal endothelial cells, and endothelial precursors), signaling molecules (growth factors, cytokines, chemical compounds, and small RNAs), and natural and synthetic scaffolds for CETE. Furthermore, we discuss the importance of three-dimensional bioprinting strategies and simulation of Descemet's membrane by biomimetic topography. Finally, we dissected the recent advances, applications, and prospects of cell sheet engineering for CETE.

Insulin-like growth factor 1 stimulates the angiogenic activity of adipose tissue-derived microvascular fragments

Angiogenesis in adipose tissue is promoted by insulin-like growth factor 1 signaling. We analyzed whether this regulatory mechanism also improves the angiogenic activity of adipose tissue-derived microvascular fragments. Murine adipose tissue-derived microvascular fragments were cultivated for 24 h in the University of Wisconsin (UW) solution supplemented with vehicle, insulin-like growth factor 1, or a combination of insulin-like growth factor 1 and insulin-like growth factor-binding protein 4. Subsequently, we assessed their cellular composition, viability, proliferation, and growth factor expression. Moreover, cultivated adipose tissue-derived microvascular fragments were seeded onto collagen-glycosaminoglycan scaffolds, which were implanted into dorsal skinfold chambers to study their vascularization and incorporation. Insulin-like growth factor 1 increased the viability and growth factor expression of adipose tissue-derived microvascular fragments without affecting their cellular composition and proliferation. Accordingly, scaffolds containing insulin-like growth factor 1-stimulated adipose tissue-derived microvascular fragments exhibited an enhanced in vivo vascularization and incorporation. These positive insulin-like growth factor 1 effects were reversed by additional exposure of adipose tissue-derived microvascular fragments to insulin-like growth factor-binding protein 4. Our findings indicate that insulin-like growth factor 1 stimulation of adipose tissue-derived microvascular fragments is suitable to improve their vascularization capacity.

Inhibition of RhoA-Subfamily GTPases Suppresses Schwann Cell Proliferation Through Regulating AKT Pathway Rather Than ROCK Pathway

Inhibiting RhoA-subfamily GTPases by C3 transferase is widely recognized as a prospective strategy to enhance axonal regeneration. When C3 transferase is administered for treating the injured peripheral nerves, Schwann cells (SCs, important glial cells in peripheral nerve) are inevitably impacted and therefore SC bioeffects on nerve regeneration might be influenced. However, the potential role of C3 transferase on SCs remains elusive. Assessed by cell counting, EdU and water-soluble tetrazolium salt-1 (WST-1) assays as well as western blotting with PCNA antibody, herein we first found that CT04 (a cell permeable C3 transferase) treatment could significantly suppress SC proliferation. Unexpectedly, using Y27632 to inhibit ROCK (the well-accepted downstream signal molecule of RhoA subfamily) did not impact SC proliferation. Further studies indicated that CT04 could inactivate AKT pathway by altering the expression levels of phosphorylated AKT (p-AKT), PI3K and PTEN, while activating AKT pathway by IGF-1 or SC79 could reverse the inhibitory effect of CT04 on SC proliferation. Based on present data, we concluded that inhibition of RhoA-subfamily GTPases could suppress SC proliferation, and this effect is independent of conventional ROCK pathway but involves inactivation of AKT pathway.

Qingchang Wenzhong Decoction Attenuates DSS-Induced Colitis in Rats by Reducing Inflammation and Improving Intestinal Barrier Function via Upregulating the MSP/RON Signalling Pathway

Ulcerative colitis (UC) is a chronic, nonspecific, inflammatory disease for which an effective treatment is lacking. Our previous study found that Qingchang Wenzhong Decoction (QCWZD) can significantly improve the clinical symptoms of UC and ameliorate dextran sulphate sodium- (DSS-) induced ulcerative colitis in rats by downregulating the IP10/CXCR3 axis-mediated inflammatory response. The purpose of the present study was to further explore the mechanism of QCWZD for UC in rats models, which were established by 7-day administration of 4.5% dextran sulphate sodium solution. QCWZD was administered daily for 7 days; then we determined the serum macrophage-stimulating protein concentration (MSP) and recepteur d'origine nantais (RON) expression and its downstream proteins (protein kinase B [Akt], phosphorylated [p] Akt, occludin, zona occluden- [ZO-] 1, and claudin-2) in colon tissue using Western blotting and quantitative polymerase chain reaction. In DSS-induced UC, QCWZD significantly alleviated colitis-associated inflammation, upregulated serum MSP expression and RON expression in the colon, reduced the pAkt levels, promoted colonic occluding and ZO-1 expression, and depressed claudin-2 expression. In conclusion, the MSP/RON signalling pathway plays an important role in the pathogenesis of UC by involving the inflammatory response and improving intestinal barrier function. QCWZD appears to attenuate DSS-induced UC in rats by upregulating the MSP/RON signalling pathway.