Dual role of PpV in Drosophila crystal cell proliferation and survival.

Drosophila melanogaster crystal cells are a specialized type of blood cells for innate immune process upon injury. Under normal conditions, crystal cells rarely proliferate and constitute a small proportion of fly blood cells. Notch signaling has been known to guide the cell fate determination of crystal cells and maintain their survival. Here, we reported that protein phosphatase V (PpV), the unique catalytic subunit of protein phosphatase 6 in Drosophila, is a novel regulator of crystal cell proliferation and integrity. We found that PpV proteins highly accumulated in crystal cells in the larval hematopoietic organ termed the lymph gland. Silencing PpV using RNA interference led to increased crystal cell proliferation in a Notch-independent manner and induced crystal cell rupture dependent on Notch signaling. Moreover, additive PpV prevented the rupture of crystal cells in lymph glands upon a needle injury, suggesting the involvement of PpV in wound healing. Altogether, our results indicated that PpV plays a dual role in lymph glands, preventing crystal cell proliferation to limit the cell number, as well as inhibiting crystal cell rupture to maintain their survival.

Ca2+-mediated reactive oxygen species signaling regulates cell repair after mechanical wounding in the red alga Griffithsia monilis.

Mechanical damage to a cell can be fatal, and the cell must reseal its membrane and restore homeostasis to survive. Plant cell repair involves additional steps such as rebuilding vacuoles, rearranging chloroplasts, and remodeling the cell wall. When we pierced a Griffithsia monilis cell with a glass needle, a large amount of intracellular contents was released, but the cell membrane resealed in less than a second. The turgor of the vacuole was quickly restored, and the punctured cell returned to its original shape within an hour. Organelles such as chloroplasts and nuclei migrated to the wound site for 12 h and then dispersed throughout the cell after the wound was covered by a new cell wall. Using fluorescent probes, high levels of reactive oxygen species (ROS) and calcium were detected at the wound site from 3 h after wounding, which disappeared when cell repair was complete. Wounding in a solution containing ROS scavengers inhibited cellular repair, and inhibiting nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity or blocking calcium influx reversibly inhibited cell repair. Oryzalin reversibly inhibited both chloroplast movement and ROS production during cell repair. Our results show that cell repair in G. monilis is regulated by calcium-mediated ROS signaling and that microtubules serve as mechanical effectors.

Mechanism of static loading injury in human skeletal muscle cells.

OBJECTIVE: To establish a cellular-level mechanical injury model for human skeletal muscle cells and investigate changes in the mechanical effect mechanism after such injuries. METHODS: The FX-5000™ Compression System was used to apply constant static mechanical pressure to human skeletal muscle cells. A factorial design analysis was conducted to discover the optimal injury model by evaluating the correlation between the amount of pressure, the duration of mechanical stimulation, and the number of days of observation. Skeletal muscle cell injury was evaluated by measuring cell metabolism, morphology, and calcium homeostasis. RESULTS: Mechanical injury was modeled as continuous pressure of 1 MPa for 2 hours with observation for 3 days. The results show that mechanical injury increased creatine kinase, intracellular Ca2+ concentration, and malondialdehyde content, decreased superoxide dismutase, and caused cell swelling and severe cytoplasmic vacuolization (all P < 0.05). CONCLUSION: This model of mechanically-injured human skeletal muscle cells provides an experimental model for the clinically common skeletal muscle injury caused by static loading pressure. It may be used to study the mechanism of action of treatment methods for mechanically injured skeletal muscle.

Edaravone Alleviates Traumatic Brain Injury by Inhibition of Ferroptosis via FSP1 Pathway.

Traumatic brain injury (TBI) is a highly severe form of trauma with complex series of reactions in brain tissue which ultimately results in neuronal damage. Previous studies proved that neuronal ferroptosis, which was induced by intracranial haemorrhage and other reasons, was one of the most primary causes of neuronal damage following TBI. However, the association between neuronal mechanical injury and ferroptosis in TBI and relevant treatments remain unclear. In the present study, we first demonstrated the occurrence of neuronal ferroptosis in the early stage of TBI and preliminarily elucidated that edaravone (EDA), a cerebroprotective agent that eliminates oxygen radicals, was able to inhibit ferroptosis induced by TBI. A cell scratching model was established in PC12 cells, and it was confirmed that mechanical injury induced ferroptosis in neurons at the early stage of TBI. Ferroptosis suppressor protein 1 (FSP1) plays a significant role in inhibiting ferroptosis, and we found that iFSP, a ferroptosis agonist which is capable to inhibit FSP1 pathway, attenuated the anti-ferroptosis effect of EDA. In conclusion, our results suggested that EDA inhibited neuronal ferroptosis induced by mechanical injury in the early phase of TBI by activating FSP1 pathway, which could provide evidence for future research on prevention and treatment of TBI.

ROCK1 deficiency preserves caveolar compartmentalization of signaling molecules and cell membrane integrity.

In this study, we investigated the roles of ROCK1 in regulating structural and functional features of caveolae located at the cell membrane of cardiomyocytes, adipocytes, and mouse embryonic fibroblasts (MEFs) as well as related physiopathological effects. Caveolae are small bulb-shaped cell membrane invaginations, and their roles have been associated with disease conditions. One of the unique features of caveolae is that they are physically linked to the actin cytoskeleton that is well known to be regulated by RhoA/ROCKs pathway. In cardiomyocytes, we observed that ROCK1 deficiency is coincident with an increased caveolar density, clusters, and caveolar proteins including caveolin-1 and -3. In the mouse cardiomyopathy model with transgenic overexpressing Gαq in myocardium, we demonstrated the reduced caveolar density at cell membrane and reduced caveolar protein contents. Interestingly, coexisting ROCK1 deficiency in cardiomyocytes can rescue these defects and preserve caveolar compartmentalization of ß-adrenergic signaling molecules including ß1-adrenergic receptor and type V/VI adenylyl cyclase. In cardiomyocytes and adipocytes, we detected that ROCK1 deficiency increased insulin signaling with increased insulin receptor activation in caveolae. In MEFs, we identified that ROCK1 deficiency increased caveolar and total levels of caveolin-1 and cell membrane repair ability after mechanical or chemical disruptions. Together, these results demonstrate that ROCK1 can regulate caveolae plasticity and multiple functions including compartmentalization of signaling molecules and cell membrane repair following membrane disruption by mechanical force and oxidative damage. These findings provide possible molecular insights into the beneficial effects of ROCK1 deletion/inhibition in cardiomyocytes, adipocytes, and MEFs under certain diseased conditions.

Investigation of healing strategies in a rat corneal opacity model with polychromatic light and stem cells injection.

Corneal opacities are a major cause of vision loss worldwide. However, the current therapies are suboptimal to manage the corneal wound healing process. Therefore, there is an obvious need to develop new treatment strategies that are efficient in promoting wound healing in patients with severe corneal disorders. In this study, we investigated and compared the efficacy of adipose-derived mesenchymal stem cells (ADMSCs) and photobiomodulation (PBM) with polychromatic light in the NIR (600-1200 nm) alone and in combination, on corneal opacity, inflammatory response, and tissue architecture in a rat corneal opacity model created by mechanical injury. All animals were divided into four groups randomly following the injury: injury only (no treatment), ADMSCs treatment, PBM treatment and combined (ADMSCs+PBM) treatment (n = 12 eyes per group). At the 10th and 30th day following injury, corneal opacity formation, neovascularization, and corneal thickness were assessed. On the 30th day the harvested corneas were analyzed by transmission electron microscopy (TEM), histological evaluation, immunohistochemical (IHC) staining and real-time polymerase chain reaction (RT-PCR). On day 30, the corneal opacity score, neovascularization grade, and corneal thickness in all treatment groups were significantly lower in comparison with the untreated injured corneas. The TEM imaging and H&E staining together clearly revealed a significant enhancement in corneal regeneration with improved corneal microenvironment and reduced vascularization in the combined administration of PBM and ADMSCs compared to treatment of PBM and ADMSCs alone. In addition, the IHC staining, and RT-PCR analysis supported our hypothesis that combining ADMSCs therapy with PBM alleviated the inflammatory response, and significantly decreased scar formation compared to either ADMSCs or PBM alone during the corneal wound healing.

A novel animal model of abdominal aortic aneurysm by mechanical injury.

The present study established a novel and reproducible animal model to study abdominal aortic aneurysms. In total, 22 adult Lewis rats underwent a procedure to produce mechanical injuries at the infrarenal aorta which was opened temporarily. The aortas were injured 6 times and repaired. Those rats were divided into 2 groups and the aortic aneurysm tissue was harvested after 42 (6-week group) or 63 (9-week group) days and evaluated for the progression of aortic aneurysms. In the 6-week group, changes in the aneurysm were observed in 6/10 (60%) rats and the mean maximum diameter of the aorta demonstrated a 119% increase in size from the baseline measurement. In the 9-week group, changes in the aneurysm were observed in 8/11 (88%) rats and the mean maximum diameter of aorta demonstrated a 133% increase in size. Additional findings from the aortic aneurysm tissue were found microscopically, including the destruction of the tunica media and the elastic fiber. The present study demonstrated that this novel animal model for the development of abdominal aortic aneurysms (AAAs) produced by mechanical injury may have high reproducibility and similar gross and microscopic morphology to humans. This model could be helpful to investigate the treatment of AAAs.

3D digital polarization-holographic wavelet histology in determining the duration of mechanical damage to the myocardium.

We aimed developing and experimentally validating methods for 3D scale-selective polarimetry of multiply scattered fields in diffuse myocardium layers for mechanical myocardial injury prescription histological differential diagnostics. We used the synthesis of diffuse object field polarization-interference registration and polarization-inhomogeneous field digital holographic reconstruction and layer-by-layer complex amplitudes distributions The method for selection single and diffuse object field multiply scattered components polarization maps is proposed. The conditions for eliminating the distorting influence of a depolarized background high level are found. On the basis of еру object field single scattered component polarization maps a large-scale selective wavelet analysis the criteria (markers) for mechanical myocardial injury different prescription diagnosis was determinate. Excellent accuracy mechanical injury myocardium necrotic changes with different duration using polarization-interference wavelet differentiation were achieved.

Stretch-injury promotes microglia activation with enhanced phagocytic and synaptic stripping activities.

Microglial cells, as the primary defense line in the central nervous system, play a crucial role in responding to various mechanical signals that can trigger their activation. Despite extensive research on the impact of chemical signaling on brain cells, the understanding of mechanical signaling in microglia remains limited. To bridge this gap, we subjected microglial cells to a singular mechanical stretch and compared their responses with those induced by lipopolysaccharide treatment, a well-established chemical activator. Here we show that stretching microglial cells leads to their activation, highlighting their significant mechanosensitivity. Stretched microglial cells exhibited distinct features, including elevated levels of Iba1 protein, a denser actin cytoskeleton, and increased persistence in migration. Unlike LPS-treated microglial cells, the secretory profile of chemokines and cytokines remained largely unchanged in response to stretching, except for TNF-α. Intriguingly, a single stretch injury resulted in more compacted chromatin and DNA damage, suggesting potential long-term genomic instabilities in stretched microglia. Using compartmentalized microfluidic chambers with neuronal networks, we observed that stretched microglial cells exhibited enhanced phagocytic and synaptic stripping activities. These findings collectively suggest that stretching events can unlock the immune potential of microglial cells, contributing to the maintenance of brain tissue homeostasis following mechanical injury.

LOX1- and PLP1-dependent transcriptional reprogramming is essential for injury-induced conidiophore development in a filamentous fungus.

IMPORTANCE: In addition to being considered a biocontrol agent, the fungus Trichoderma atroviride is a relevant model for studying mechanisms of response to injury conserved in plants and animals that opens a new landscape in relation to regeneration and cell differentiation mechanisms. Here, we reveal the co-functionality of a lipoxygenase and a patatin-like phospholipase co-expressed in response to wounding in fungi. This pair of enzymes produces oxidized lipids that can function as signaling molecules or oxidative stress signals that, in ascomycetes, induce asexual development. Furthermore, we determined that both genes participate in the regulation of the synthesis of 13-HODE and the establishment of the physiological responses necessary for the formation of reproductive aerial mycelium ultimately leading to asexual development. Our results suggest an injury-induced pathway to produce oxylipins and uncovered physiological mechanisms regulated by LOX1 and PLP1 to induce conidiation, opening new hypotheses for the novo regeneration mechanisms of filamentous fungi.

[Evaluation of the duration of fixation of adhesive products in the treatment of traumatic lesions of the oral mucosa]. / Otsenka dlitel'nosti fiksatsii adgezivnykh sredstv pri lechenii travmaticheskikh porazhenii slizistoi obolochki rta.

OBJECTIVE: The purpose of this study was to evaluate the duration of fixation of adhesive films in the treatment of traumatic lesions of the oral mucosa. MATERIAL AND METHODS: The patients were divided into 2 groups. In the first group, the affected area was covered with an adhesive film with solcoseryl, in the second group with a film with vitamin E. The film was glued to the affected area according to the instructions, the time of gluing was recorded, patients were warned about the need to notify researchers via messengers or SMS messages about the time of peeling or resorption of the film. The evaluation was carried out by the method of variation statistics (Student's t-test for independent samples). RESULTS: The retention time of the film in the oral cavity was expressed in minutes, the average value in group 1 was 48.4±9.19, in group 2 - 127.70±49.07. Thus, the fixation of the film with vitamin E was longer than the films with solcoseryl (p=0.000180). CONCLUSION: Both films provided sufficient protective effect during the retention period. However, in clinical situations where a longer barrier protective effect to the damaged oral mucosa surface is required, it is advisable to use a vitamin E healing patch.

Human endometrium-derived mesenchymal stem/stromal cells application in endometrial-factor induced infertility.

Endometrial-factor induced infertility remains one of the most significant pathology among all fertility disorders. Stem cell-based therapy is considered to be the next-generation approach. However, there are still issues about successfully retrieving human endometrium-derived mesenchymal stem/stromal cells (hEnMSCs). Moreover, we need to establish a better understanding of the effect of hEnMSCs on the endometrial recovery and the clinical outcome. According to these challenges we created a multi-step study. Endometrium samples were collected from females undergoing assisted reproductive technology (ART) procedure due to couple infertility. These samples were obtained using an endometrium scratching. The hEnMSCs were isolated from endometrium samples and characterized with flow cytometry analysis. Groups of endometrium injured female mice were established by the mechanical injury to uterine horns and the intraperitoneal chemotherapy. The hEnMSCs suspension was injected to some of the studied female mice at approved time intervals. Histological changes of mice uterine horns were evaluated after Masson's trichrome original staining, hematoxylin and eosin (H&E) staining. The fertility assessment of mice was performed by counting formed embryo implantation sites (ISs). The expression of fibrosis related genes (Col1a1, Col3a1, Acta2, and CD44) was evaluated by the reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Results showed that endometrium scratching is an effective procedure for mesenchymal stem/stromal cells (MSCs) collection from human endometrium. Isolated hEnMSCs met the criteria for defining MSCs. Moreover, hEnMSCs-based therapy had a demonstrably positive effect on the repair of damaged uterine horns, including a reduction of fibrosis, intensity of inflammatory cells such as lymphocytes and polymorphonuclear cells (PMNs) and the number of apoptotic bodies. The injured mice which recieved hEnMSCs had higher fertility in comparison to the untreated mice. Gene expression was reflected in histology changes and outcomes of conception. In conclusion, hEnMSCs demonstrated a positive impact on endometrium restoration and outcomes of endometrial-factor induced infertility. Further exploration is required in order to continue exploring the multifactorial associations between stem cell therapy, gene expression, endometrial changes and reproductive health, so we can identify individually effective and safe treatment strategies for endometrial-factor induced infertility, which is caused by mechanical effect or chemotherapy, in daily clinical practise.

Study on the mechanism of estrogen regulating endometrial fibrosis after mechanical injury via miR-21-5p/PPARα/FAO axis.

BACKGROUND: Intrauterine adhesion (IUA) caused by endometrial mechanical injury has been found as a substantial risk factor for female infertility (e.g., induced abortion). Estrogen is a classic drug for the repair of endometrial injury, but its action mechanism in the clinical application of endometrial fibrosis is still unclear. OBJECTIVE: To explore the specific action mechanism of estrogen treatment on IUA. METHODS: The IUA model in vivo and the isolated endometrial stromal cells (ESCs) model in vitro were built. Then CCK8 assay, Real-Time PCR, Western Blot and Dual-Luciferase Reporter Gene assay were applied to determine the targeting action of estrogen on ESCs. RESULTS: It was found that 17ß-estradiol inhibited fibrosis of ESCs by down-regulating miR-21-5p level and activating PPARα signaling. Mechanistically, miR-21-5p significantly reduced the inhibitory effect of 17ß-estradiol on fibrotic ESCs (ESCs-F) and its maker protein (e.g., α-SMA, collagen I, and fibronectin), where targeting to PPARα 3'-UTR and blocked its activation and transcription, thus lowering expressions of fatty acid oxidation (FAO) associated key enzyme, provoking fatty accumulation and reactive oxygen species (ROS) production, resulting in endometrial fibrosis. Nevertheless, the PPARα agonist caffeic acid counteracted the facilitation action of miR-21-5p on ESCs-F, which is consistent with the efficacy of estrogen intervention. CONCLUSION: In brief, the above findings revealed that the miR-21-5p/PPARα signal axis played an important role in the fibrosis of endometrial mechanical injury and suggested that estrogen might be a promising agent for its progression.

Effects of needle puncturing on re-vascularization and follicle survival in xenotransplanted human ovarian tissue.

BACKGROUND: Ovarian tissue transplantation can restore fertility in young cancer survivors, however the detrimental loss of follicles following transplantation of cryopreserved ovarian tissue is hampering the efficiency of the procedure. This study investigates whether needle puncturing prior to transplantation can enhance revascularization and improve follicle survival in xenotransplanted human ovarian cortex. METHODS: Cryopreserved human ovarian cortex pieces (N = 36) from 20 women aged 24-36 years were included. During the thawing process, each piece of tissue was cut in halves; one half serving as the untreated control and the other half was punctured approximately 150-200 times with a 29-gauge needle. The cortex pieces were transplanted subcutaneously to immunodeficient mice for 3, 6 and 10 days (N = 8 patients) and for 4 weeks (N = 12 patients). After 3, 6 and 10 days, revascularization of the ovarian xenografts were assessed using immunohistochemical detection of CD31 and gene expression of angiogenic factors (Vegfα, Angptl4, Ang1, and Ang2), and apoptotic factors (BCL2 and BAX) were performed by qPCR. Follicle density and morphology were evaluated in ovarian xenografts after 4 weeks. RESULTS: A significant increase in the CD31 positive area in human ovarian xenografts was evident from day 3 to 10, but no significant differences were observed between the needle and control group. The gene expression of Vegfα was consistently higher in the needle group compared to control at all three time points, but not statistically significant. The expression of Ang1 and Ang2 increased significantly from day 3 to day 10 in the control group (p < 0.001, p = 0.0023), however, in the needle group this increase was not observed from day 6 to 10 (Ang2 p = 0.027). The BAX/BCL2 ratio was similar in the needle and control groups. After 4-weeks xenografting, follicle density (follicles/mm3, mean ± SEM) was higher in the needle group (5.18 ± 2.24) compared to control (2.36 ± 0.67) (p = 0.208), and a significant lower percentage of necrotic follicles was found in the needle group (19%) compared to control (36%) (p = 0.045). CONCLUSIONS: Needle puncturing of human ovarian cortex prior to transplantation had no effect on revascularization of ovarian grafts after 3, 6 and 10 days xenotransplantation. However, needle puncturing did affect angiogenic genes and improved follicle morphology.

Partial compression increases acidity, but decreases phenolics in jujube fruit: Evidence from targeted metabolomics.

Jujube fruit (Ziziphus jujuba Mill.) is extremely susceptible to mechanical injury by extrusion and collision during storage, transportation and processing. In this study, we examined the morphology and endogenous metabolism of jujubes at three developmental stages after applying partial compression (PC) to mimic mechanical injury. Generally, PC did not affect the total soluble solids content, but increased the acidity and decreased the amount of phenolics in the jujube fruit. Targeted metabolomics analysis further confirmed that acid and phenolics content were differentially altered in response to PC. To our knowledge, this is the first study to characterize metabolic variations in ready-to-eat fruit that occur in response to physical damage. The results will provide insight into the understanding the consequences of mechanical injury on fruit nutrition and health benefits.

Evaluation of different rat models intrauterine adhesion models and improvement of the technique for their establishment.

Intrauterine adhesion (IUA), a leading cause of uterine infertility, is characterized by endometrial fibrosis. Implementing an appropriate animal model is essential for the research on the mechanisms of IUA. In the present study, we established and evaluated different intrauterine adhesion modeling procedures in rats to provide a reference for researchers. Rat IUA models were established by mechanical injury, 95% ethanol injection, and dual (mechanical injury with infection) injury. After two estrus cycles, the female rats were mated with sexually mature male rats, and uterine tissues were obtained on the 5th day of pregnancy. Hematoxylin and eosin staining and immunohistochemical detection of cytokeratin 19 and vimentin were performed to assess the morphology of the endometrium. Masson's trichrome staining and the expression of transforming growth factor-ß1 and collagen I were used to assess the endometrium fibrosis. The expression of integrin avß3, leukemia inhibitory factor, and homeobox gene A10 in the rat endometrium was used to evaluate the endometrial receptivity. In addition, the efficiency of embryo implantation was examined in the uterus on the 8th day of pregnancy. Our study found that mechanical injury caused by a curette can be completely repaired after two estrus cycles. However, dual injury and 95% ethanol injection can be used to establish an IUA rat model, and the dual injury is closer to the clinicpathological characteristics of IUA.

Integrative biology of injury in animals.

Mechanical injury is a prevalent challenge in the lives of animals with myriad potential consequences for organisms, including reduced fitness and death. Research on animal injury has focused on many aspects, including the frequency and severity of wounding in wild populations, the short- and long-term consequences of injury at different biological scales, and the variation in the response to injury within or among individuals, species, ontogenies, and environmental contexts. However, relevant research is scattered across diverse biological subdisciplines, and the study of the effects of injury has lacked synthesis and coherence. Furthermore, the depth of knowledge across injury biology is highly uneven in terms of scope and taxonomic coverage: much injury research is biomedical in focus, using mammalian model systems and investigating cellular and molecular processes, while research at organismal and higher scales, research that is explicitly comparative, and research on invertebrate and non-mammalian vertebrate species is less common and often less well integrated into the core body of knowledge about injury. The current state of injury research presents an opportunity to unify conceptually work focusing on a range of relevant questions, to synthesize progress to date, and to identify fruitful avenues for future research. The central aim of this review is to synthesize research concerning the broad range of effects of mechanical injury in animals. We organize reviewed work by four broad and loosely defined levels of biological organization: molecular and cellular effects, physiological and organismal effects, behavioural effects, and ecological and evolutionary effects of injury. Throughout, we highlight the diversity of injury consequences within and among taxonomic groups while emphasizing the gaps in taxonomic coverage, causal understanding, and biological endpoints considered. We additionally discuss the importance of integrating knowledge within and across biological levels, including how initial, localized responses to injury can lead to long-term consequences at the scale of the individual animal and beyond. We also suggest important avenues for future injury biology research, including distinguishing better between related yet distinct injury phenomena, expanding the subjects of injury research to include a greater variety of species, and testing how intrinsic and extrinsic conditions affect the scope and sensitivity of injury responses. It is our hope that this review will not only strengthen understanding of animal injury but will contribute to building a foundation for a more cohesive field of 'injury biology'.

Ca2+ Regulates Autophagy Through CaMKKß/AMPK/mTOR Signaling Pathway in Mechanical Spinal cord Injury: An in vitro Study.

Spinal cord injury (SCI), resulting in damage of the normal structure and function of the spinal cord, would do great harm to patients, physically and psychologically. The mechanism of SCI is very complex. At present, lots of studies have reported that autophagy was involved in the secondary injury process of SCI, and several researchers also found that calcium ions (Ca2+) played an important role in SCI by regulating necrosis, autophagy, or apoptosis. However, to our best of knowledge, no studies have linked the spinal cord mechanical injury, intracellular Ca2+, and autophagy in series. In this study, we have established an in vitro model of SCI using neural cells from fetal rats to explore the relationship among them, and found that mechanical injury could promote the intracellular Ca2+ concentration, and the increased Ca2+ level activated autophagy through the CaMKKß/AMPK/mTOR pathway. Additionally, we found that apoptosis was also involved in this pathway. Thus, our study provides new insights into the specific mechanisms of SCI and may open up new avenues for the treatment of SCI.

Protective effect of etomidate on cultured retinal ganglion cells with mechanical injury in vitro / 中华眼底病杂志

Objective:To observe the protective effect of etomidate (ET) on cultured retinal ganglion cells (RGC) with mechanical injury in vitro.Methods:New Sprague-Dawley rat RGC was cultured in vitro and identified by double immunofluorescent labeling of Thy1.1 and microtubule associated protein 2. The cultured primary cells were randomly divided into control group, RGC scratch group, ET low dose group (1 μmol/L), ET medium dose group (5 μmol/L) and ET high dose group (10 μmol/L). The RGC mechanical injury model was established by using iris knife to culture cells in RGC scratch group and ET group with different concentration. Seven days after modeling, the RGC survival rate of each group was detected by cell count Kit 8 proliferation assay. The apoptosis rate of RGC was detected by Annexin Ⅴ/propyl iodide double staining. Single factor analysis of variance was used to compare the groups. The pairwise comparison between groups was tested by the least significant difference method.Results:The survival rates of RGC in RGC scratch group, ET low dose group, ET medium dose group and ET high dose group were (72.60±2.97)%, (73.73±1.14)%, (79.19±1.79)% and (83.88±0.94)%, respectively. The RGC apoptosis rates of control group, RGC scratch group, ET low dose group, ET medium dose group and ET high dose group were (5.08±0.17)%, (18.67±1.24)%, (17.96±0.74)%, (15.11±0.56)% and (11.67±1.32)%, respectively. Comparison of RGC survival rate between groups: compared with RGC scratch group, the cell survival rate of ET low-dose group, ET medium-dose group and ET high-dose group was increased, and the difference between RGC scratch group and ET low-dose group was not statistically significant ( P=0.728); the differences between RGC scratch group, ET medium dose group and ET high dose group were statistically significant ( P<0.001); the difference between ET medium dose group and ET high dose group was statistically significant ( P=0.002). Comparison of apoptosis rate of RGC among groups: the apoptosis rate of RGC scratch group was significantly higher than that of control group, the difference was statistically significant ( P<0.001). Compared with RGC scratch group, the apoptosis rate of ET low-dose group, ET medium-dose group and ET high-dose group was decreased, and there was no statistical significance between RGC scratch group and ET low-dose group ( P=0.869). The differences of apoptosis rate between RGC scratch group, ET medium dose group and ET high dose group were statistically significant ( P<0.05). The difference of apoptosis rate between ET medium dose group and ET high dose group was statistically significant ( P=0.007). Conclusion:ET has neuroprotective effect on RGC cultured in vitro with mechanical injury, and the protective effect increases with the increase of ET dose in a certain range.

Genipin does not reduce the initiation or propagation of microcracks in collagen networks of cartilage.

Objective: We recently initiated microcracks, i.e. micron-scale cracks in the collagen networks of cartilage, using both single low-energy impacts and unconfined, cyclic compressions. We also tracked the propagation of microcracks after cyclic compressions simulating 12,000 walking strides. In this study, we aimed to determine the effect of one or more genipin treatments on: (1) the initiation of microcracks under mechanical impacts and (2) the subsequent propagation of microcracks under cyclic, unconfined compression. We hypothesized that treatments with genipin would improve the resistance of cartilage to microdamage, specifically reducing both the initiation of microcracks under impact loading and the propagation of microcracks under cyclic compression. Design: We tested 49 full-thickness, cylindrical osteochondral specimens. We incorporated one or two doses of genipin in between mechanical treatments, i.e. single low-energy mechanical impacts to initiate microcracks and unconfined, cyclic compressions to propagate microcracks. We also imaged specimens using second harmonic generation confocal microscopy, and analyzed the resulting images to quantify changes in morphologies (length, width, and depth) and orientations of microcracks. Finally, we used separate mixed-regression modeling to evaluate the effects of genipin treatments on mechanically induced microcracks. Results: Specimens treated with genipin presented significantly longer and marginally deeper microcracks after mechanical impacts. Two doses of genipin caused significantly longer and wider microcracks under propagation verses one dose. Conclusions: Our results do not support our hypothesis: unfortunately treatments with genipin, and the resulting mechanisms of cross-linking, do not provide resistance to microdamage, quantified as the initiation and propagation of microcracks.