Awareness of Cornea Donation of Registered Tissue Donors in Nanjing

Objective To evaluate the current cornea donation awareness of tissue donors in the city of Nanjing, China Methods Altogether 2000 registered tissue donors in the Red Cross Eye Bank of Nanjing by the end of 2010 and 2000 control residents of Nanjing in February to June 2011 were randomly selected to par- ticipate in our field questionnaire survey. The questionnaire consisted of questions regarding the understand- ing of cornea donation, the attitude toward cornea donation, and attitude toward legislation and free dona- tion. The awareness of cornea donation between the registered tissue donors and residents was compared. Related factors of the willingness to donate corneas and to become a tissue donor were evaluated with uni- variate and multiple logistic regression analysis. Results A total of 1867 （response rate： 93.4%） tissue donors and 1796 （response rate： 89.8%; ef- fective questionnaires： 1697） residents participated in this survey. For the questions about the knowledge of cornea donation, 90.3% tissue donors （residents： 78.9%） knew that donated corneas could be used for transplantations; 71.2% tissue donors （residents： 47.6%） knew that the appearance would not be destroyed after cornea donation; 70.7% tissue donors （residents： 20.0%） knew the formalities to become a cornea do- nor. For attitude toward cornea donation, 82.2% tissue donors （residents： 45.1%） were willing to donate corneas or eyeballs after death; 84.0% tissue donors （residents： 30.2%） had discussed with their families about donation; 85.1% tissue donors （residents： 24.8%） supported their families＇ or friends＇ cornea donation For attitude toward legislation and free donation, 88.3% tissue donors （residents： 61.3%） approved of legis- lation to regular cornea donation; 72.2% tissue donors （residents： 38.8%） thought that cornea or organ do- nation should be gratis. The difference between two groups was significant （P〈0.001）. However, some tissue donors did not know cornea donation well, some even opposed the legislation of cornea donation and free donation protocol. For the factors influencing the willingness to donate corneas, population was the mostrelevant factor （P〈0.O01）, since tissue donors were more willing to donate corneas than residents. Other significantly related factor were age, gender, occupation, and education level （P〈0.001 ）, while political status or religion were not significant. For the factors related to becoming a tissue donor, older age, male, white-collars （including white-collar, civil servant, teacher, soldier, lawyer, salesman, healthcare provider）, higher education level, party members （including the Chinese Communist Party members, democratic party members, and the CommunistYouth League members） （P〈0.05）. Conclusions The registered tissue donors have better understanding and more positive attitude to- wards cornea donation than control residents do. They approve of the legislation of cornea donation and free donation protocol. It may be more effective to target the population of over 58 years old, male, white-collars, well-educated people, and party members in the promotion of cornea donation.

Biomimetic natural biomaterials for tissue engineering and regenerative medicine:new biosynthesis methods,recent advances,and emerging applications

Biomimetic materials have emerged as attractive and competitive alternatives for tissue engineering(TE)and regenerative medicine.In contrast to conventional biomaterials or synthetic materials,biomimetic scaffolds based on natural biomaterial can offer cells a broad spectrum of biochemical and biophysical cues that mimic the in vivo extracellular matrix(ECM).Additionally,such materials have mechanical adaptability,micro-structure interconnectivity,and inherent bioactivity,making them ideal for the design of living implants for specific applications in TE and regenerative medicine.This paper provides an overview for recent progress of biomimetic natural biomaterials(BNBMs),including advances in their preparation,functionality,potential applications and future challenges.We highlight recent advances in the fabrication of BNBMs and outline general strategies for functionalizing and tailoring the BNBMs with various biological and physicochemical characteristics of native ECM.Moreover,we offer an overview of recent key advances in the functionalization and applications of versatile BNBMs for TE applications.Finally,we conclude by offering our perspective on open challenges and future developments in this rapidly-evolving field.

Visceral adipose tissue predicts severity and prognosis of acute pancreatitis in obese patients

Acute pancreatitis is a common systemic inflammatory disease, manifested by a spectrum of severity, ranging from mild in the majority of patients to severe acute pancreatitis. Patients with severe acute pancreatitis suffer from severe local and systemic complications and organ failure, leading to a poor prognosis. The early recognition of the severe condition is important to improve prognosis. Obesity has risen in tandem with an increase in the severity of acute pancreatitis in recent years. Studies have revealed that adipose tissue, particularly visceral adipose tissue is associated with the prognosis of acute pancreatitis. This review discussed the role of visceral adipose tissue in obese patients with acute pancreatitis and explored the possible mechanism involved.

Biomaterials and tissue engineering in traumatic brain injury:novel perspectives on promoting neural regeneration

Traumatic brain injury is a serious medical condition that can be attributed to falls, motor vehicle accidents, sports injuries and acts of violence, causing a series of neural injuries and neuropsychiatric symptoms. However, limited accessibility to the injury sites, complicated histological and anatomical structure, intricate cellular and extracellular milieu, lack of regenerative capacity in the native cells, vast variety of damage routes, and the insufficient time available for treatment have restricted the widespread application of several therapeutic methods in cases of central nervous system injury. Tissue engineering and regenerative medicine have emerged as innovative approaches in the field of nerve regeneration. By combining biomaterials, stem cells, and growth factors, these approaches have provided a platform for developing effective treatments for neural injuries, which can offer the potential to restore neural function, improve patient outcomes, and reduce the need for drugs and invasive surgical procedures. Biomaterials have shown advantages in promoting neural development, inhibiting glial scar formation, and providing a suitable biomimetic neural microenvironment, which makes their application promising in the field of neural regeneration. For instance, bioactive scaffolds loaded with stem cells can provide a biocompatible and biodegradable milieu. Furthermore, stem cells-derived exosomes combine the advantages of stem cells, avoid the risk of immune rejection, cooperate with biomaterials to enhance their biological functions, and exert stable functions, thereby inducing angiogenesis and neural regeneration in patients with traumatic brain injury and promoting the recovery of brain function. Unfortunately, biomaterials have shown positive effects in the laboratory, but when similar materials are used in clinical studies of human central nervous system regeneration, their efficacy is unsatisfactory. Here, we review the characteristics and properties of various bioactive materials, followed by the introduction of applications based on biochemistry and cell molecules, and discuss the emerging role of biomaterials in promoting neural regeneration. Further, we summarize the adaptive biomaterials infused with exosomes produced from stem cells and stem cells themselves for the treatment of traumatic brain injury. Finally, we present the main limitations of biomaterials for the treatment of traumatic brain injury and offer insights into their future potential.

Process,Material,and Regulatory Considerations for 3D Printed Medical Devices and Tissue Constructs

Three-dimensional(3D)printing is a highly automated platform that facilitates material deposition in a layer-by-layer approach to fabricate pre-defined 3D complex structures on demand.It is a highly promising technique for the fabrication of personalized medical devices or even patient-specific tissue constructs.Each type of 3D printing technique has its unique advantages and limitations,and the selection of a suitable 3D printing technique is highly dependent on its intended application.In this review paper,we present and highlight some of the critical processes(printing parameters,build orientation,build location,and support structures),material(batch-to-batch consistency,recycling,protein adsorption,biocompatibility,and degradation properties),and regulatory considerations(sterility and mechanical properties)for 3D printing of personalized medical devices.The goal of this review paper is to provide the readers with a good understanding of the various key considerations(process,material,and regulatory)in 3D printing,which are critical for the fabrication of improved patient-specific 3D printed medical devices and tissue constructs.

Engineering vascularized organotypic tissues via module assembly

Adequate vascularization is a critical determinant for the successful construction and clinical implementation of complex organotypic tissue models. Currently, low cell and vessel density and insufficient vascular maturation make vascularized organotypic tissue construction difficult,greatly limiting its use in tissue engineering and regenerative medicine. To address these limitations, recent studies have adopted pre-vascularized microtissue assembly for the rapid generation of functional tissue analogs with dense vascular networks and high cell density. In this article, we summarize the development of module assembly-based vascularized organotypic tissue construction and its application in tissue repair and regeneration, organ-scale tissue biomanufacturing, as well as advanced tissue modeling.

Impact of Regular Blood Donation on Body Iron Stores at Saudi Blood Donors

Introduction: One of the most frequent observations in long-term blood donation is chronic iron deficiency, which can develop into anaemia. The majority of blood screening methods employed by blood banks do not incorporate iron-status markers, which may result in potential subclinical iron deficiency. The aim of this study was to evaluate the effects of repeated blood donation on the levels of iron in the body and to guide blood donors in preventing the depletion of iron stores. Methods: Regular blood donors were categorised into distinct groups according to the number of donations they gave, and then the correlation between these groups and their bodies’ iron levels was examined. Different parameters were employed to identify iron deficiency and iron depletion in blood donors: serum ferritin, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), total iron-binding capacity (TIBC), and serum iron. Results: The study included 300 individuals who regularly and willingly donated blood. There were no iron insufficiency cases among those donating blood for the first time (Group I). However, 15.5% of individuals who had donated once before (Group II) had ferritin levels of 15 - 30 μg/dl (ng/ml), indicating reduced iron stores. The rate increased to 18% (37 out of 206 individuals) among regular blood donors (Groups III, IV, and V). Iron deficiency (depletion) prevalence among regular blood donors in Groups III, IV, and V was 5.9% (12 out of 206) and 50.4% (100 out of 206). Donors who had donated blood most frequently had the lowest levels of haematological markers MCH, MCHC, and TIBC. Provide the p-values representing the differences between the means of MCV, MCH, iron, TIBC, and ferritin levels when comparing donor groups with the control group (Group I) based on the frequency of donations. Indicate statistically significant differences where the p-value is less than 0.0125. This significance level is adjusted based on the Bonferroni method, considering multiple independent tests. The result shows that the Iron parameter for the comparison between Group I and Group III and Group I and Group IV suggests a statistically significant difference in iron levels between these donor groups. Conclusion: The findings of this study show that a higher times of donations lads to a higher occurrence of depleted iron stores and subsequent erythropoiesis with iron deficiency by one donor from every three healthy donors. The iron and ferritin concentrations were within the normal range in group one (Control group) and reduced in the other four groups (G-2 to G-5). However, the level of haemoglobin remained within an acceptable range for blood donation. This outcome suggests that it may be necessary to reassess the criteria for accepting blood donors. The average serum ferritin levels were examined in all five groups (G-1 to G-5), both for males and females, and significant variations were seen among the groups under study. This study found that 35% of the individuals who regularly donate blood have iron-deficient anaemia (sideropenia). This suggests that it would be beneficial to test for serum ferritin at an earlier stage, ideally after three donations.

Characteristics and mechanisms of subcutaneous and visceral adipose tissue aging

Aging is one of the most significant health challenges worldwide and is a primary cause of chronic diseases and physiological decline.Among the myriad changes that occur with aging,alterations in adipose tissue distribution and function have gained considerable attention because of their profound impact on metabolic health and overall well-being.Subcutaneous adipose tissue(SAT)and visceral adipose tissue(VAT)are the two major depots of white adipose tissue,each with distinct roles in metabolism and health.Understanding the characteristics and underlying mechanisms of SAT and VAT is crucial for elucidating the aging process and developing strategies to promote healthy aging.This review focuses on delineating and analyzing the characteristics and intrinsic mechanisms underlying the aging of subcutaneous and visceral adipose tissue during the aging process,which can contribute to a better understanding of the aging process and enhance healthy aging.

Interplay between mesenchymal stem cells and macrophages:Promoting bone tissue repair

The repair of bone tissue damage is a complex process that is well-orchestrated in time and space,a focus and difficulty in orthopedic treatment.In recent years,the success of mesenchymal stem cells(MSCs)-mediated bone repair in clinical trials of large-area bone defects and bone necrosis has made it a candidate in bone tissue repair engineering and regenerative medicine.MSCs are closely related to macrophages.On one hand,MSCs regulate the immune regulatory function by influencing macrophages proliferation,infiltration,and phenotype polarization,while also affecting the osteoclasts differentiation of macrophages.On the other hand,macrophages activate MSCs and mediate the multilineage differentiation of MSCs by regulating the immune microenvironment.The cross-talk between MSCs and macrophages plays a crucial role in regulating the immune system and in promoting tissue regeneration.Making full use of the relationship between MSCs and macrophages will enhance the efficacy of MSCs therapy in bone tissue repair,and will also provide a reference for further application of MSCs in other diseases.

Research on the Development of Fibroin and Nano-Fiber from Silk Cocoons for Regenerated Tissue Engineering Applications by Electro-Spinning

In this paper, the main goal is to prepare silk fibroin nano-fiber, which is used for regenerated tissue applications. Silk scaffold nano-fibers made by electro-spinning technology can be used in regenerated tissue applications. The purpose of the research is to prepare a silk-fibroin nano-fiber solution for potential applications in tissue engineering. Using a degumming process, pure silk fibroin protein is extracted from silk cocoons. The protein solution for fibroin is purified, and the protein content is determined. The precise chemical composition, exact temperature, time, voltage, distance, ratio, and humidity all have a huge impact on degumming, solubility, and electro-spinning nano-fibers. The SEM investigates the morphology of silk fibroin nano-fibres at different magnifications. It also reveals the surface condition, fiber orientation, and fiber thickness of the silk fibroin nano-fiber. The results show that regenerated silk fibroin and nano-fiber can be used in silk fibroin scaffolds for various tissue engineering applications.

Magnesium-incorporated biocomposite scaffolds:A novel frontier in bone tissue engineering

Nonunion represents a crucial challenge in orthopedic medicine,demanding innovative solutions beyond the scope of traditional bone grafting methods.Among the various strategies available,magnesium(Mg)implants have been recognized for their biocompatibility and biodegradability.However,their susceptibility to rapid corrosion and degradation has garnered notable research interest in bone tissue engineering(BTE),particularly in the development of Mg-incorporated biocomposite scaffolds.These scaffolds gradually release Mg2+,which enhances immunomodulation,osteogenesis,and angiogenesis,thus facilitating effective bone regeneration.This review presents myriad fabrication techniques used to create Mg-incorporated biocomposite scaffolds,including electrospinning,three-dimensional printing,and sol-gel synthesis.Despite these advancements,the application of Mg-incorporated biocomposite scaffolds faces challenges such as controlling the degradation rate of Mg and ensuring mechanical stability.These limitations highlight the necessity for ongoing research aimed at refining fabrication techniques to better regulate the physicochemical and osteogenic properties of scaffolds.This review provides insights into the potential of Mg-incorporated biocomposite scaffolds for BTE and the challenges that need to be addressed for their successful translation into clinical applications.

Biomimetic Erythrocyte-Like Particles from Microfluidic Electrospray for Tissue Engineering

Microparticles have demonstrated value for regenerative medicine.Attempts in this field tend to focus on the development of intelligent multifunctional microparticles for tissue regeneration.Here,inspired by erythrocytes-associated self-repairing process in damaged tissue,we present novel biomimetic erythrocyte-like microparticles(ELMPs).These ELMPs,which are composed of extracellular matrix-like hybrid hydrogels and the functional additives of black phosphorus,hemoglobin,and growth factors(GFs),are generated by using a microfluidic electrospray.As the resultant ELMPs have the capacity for oxygen delivery and near-infrared-responsive release of both GFs and oxygen,they would have excellent biocompatibility and multifunctional performance when serving as microscaffolds for cell adhesion,stimulating angiogenesis,and adjusting the release profile of cargoes.Based on these features,we demonstrate that the ELMPs can stably overlap to fill a wound and realize controllable cargo release to achieve the desired curative effect of tissue regeneration.Thus,we consider our biomimetic ELMPs with discoid morphology and cargo-delivery capacity to be ideal for tissue engineering.

Quality of Life in Living Kidney Donors Grenoble Teaching Hospital (France)

Context: Kidney transplantation is today the standard treatment for patients suffering from chronic end-stage renal failure. Living kidney donation offers many advantages for the recipient, but requires a subject without comorbidities to undergo surgery. The aim of this study was to assess the quality of life and psychosocial experience of living kidney donors after donation. Methods: This was a cross-sectional study with an analytical aim, involving living kidney donors during the period from January 2016 to April 2019 at CHUGA. (University Hospital Center of Grenoble Alpes in France). Results: Our study shows that out of 88 donors, 70 responded to our questionnaires, representing a prevalence of 80.5%. The average age of our donors was 55.6 years with a female predominance. Seven out of eight domains of the SF36 score had a good quality of life after donation and the donation did not alter their psychosocial experience. The majority of our donors expressed their pride and enthusiasm, did not regret having saved a life, and this experience was considered positive. Conclusion: Kidney donation does not have a negative impact on quality of life and psychosocial life. The majority of donors do not regret their donation. The dissemination of such results could make it possible to increase the number of kidney transplants from living donors in France, especially in our African countries where the management of ESRD remains a real public health problem.

Engineering of ovarian tissue for ovarian dysfunctions:A review

This review explores tissue engineering as a potential solution for reproductive health issues in women caused by genetic or acquired diseases,such as premature ovarian failure or oophorectomy.The loss of ovarian function can lead to infertility,osteoporosis,and cardiovascular disease.Hormone replacement therapy is a common treatment,but it has limitations and risks.The review focuses on two main approaches in tissue engineering:scaffold-based(3D printing,electrospinning,decellularization)and scaffold-free(stem cell transplantation,organoid cultivation).Both approaches show promise in preclinical studies for creating functional ovarian tissue.Challenges include vascularization,innervation,long-term function,and safety.Despite these challenges,tissue engineering offers a potential avenue for restoring fertility and hormone balance in women with ovarian dysfunction.

Seroprevalence of Human Immunodeficiency Virus and Hepatitis B in Blood Donors at the N’Zérékoré Regional Blood Transfusion Centre in Guinea

Blood transfusion saves lives and reduces morbidity and mortality for a large number of diseases and clinical conditions, but it is not without danger. The aim of this study was to determine the seroprevalence of HIV and hepatitis B in blood donors received at the regional Blood Transfusion Centre of N’Zérékoré (Guinea). This was a 5-year retrospective analytical study. We included records of blood donors aged 18 to 60 years admitted to the N’Zérékoré Regional Blood Transfusion Centre for blood donation from January 2016 to December 2020. We performed a descriptive analysis followed by Chi-2 or Fish-er-exact tests and the Student or Wilcoxon test, followed by multivariate logistic regression. In this study, donor age ranged from 18 - 60 years, with a pre-dominance of donors aged 25 - 34 (44.2%). Male donors were the most represented in our study (79.0% versus 21.0% female). More than half of the donors were blood group O (55.6%). We observed a seroprevalence of 3.6% for HIV, 13.4% for HBsAg and 0.2% for co-infection. In our series, age 25 - 34 (OR = 1.89 and P = 0.001) and 35 - 44 for HIV (OR = 2.01 and P = 0.001), HBsAgserostatus (OR = 3.04 and P = 0.001) and blood donation history (OR of 3.04 and P = 0.001) were factors associated with HIV positivity (P < 0.05). In our study, HIV serostatus (OR = 3.04 and P = 0.001) and blood donation history (OR = 0.01 and P = 0.001) were factors associated with HBsAgseropositivity. We reported a high prevalence of HIV and HBsAg. Sex, serological status and blood donation history were associated factors.

A Review on Silk Fibroin as a Biomaterial in Tissue Engineering

Regenerative medicine progress is based on the development of cell and tissue bioengineering. One of the aims of tissue engineering is the development of scaffolds, which should substitute the functions of the replaced organ after their implantation into the body. The tissue engineering material must meet a range of requirements, including biocompatibility, mechanical strength, and elasticity. Furthermore, the materials have to be attractive for cell growth: stimulate cell adhesion, migration, proliferation and differentiation. One of the natural biomaterials is silk and its component (silk fibroin). An increasing number of scientists in the world are studying silk and silk fibroin. The purpose of this review article is to provide information about the properties of natural silk (silk fibroin), as well as its manufacture and clinical application of each configuration of silk fibroin in medicine. Materials and research methods. Actual publications of foreign authors on resources PubMed, Medline, E-library have been analyzed. The selection criteria were materials containing information about the structure and components of silk, methods of its production in nature. This article placed strong emphasis on silk fibroin, the ways of artificial modification of it for use in various sphere of medicine.

Endotoxin-induced alterations of adipose tissue function:a pathway to bovine metabolic stress

During the periparturient period, dairy cows exhibit negative energy balance due to limited appetite and increased energy requirements for lactogenesis. The delicate equilibrium between energy availability and expenditure puts cows in a state of metabolic stress characterized by excessive lipolysis in white adipose tissues(AT), increased production of reactive oxygen species, and immune cell dysfunction. Metabolic stress, especially in AT, increases the risk for metabolic and inflammatory diseases. Around parturition, cows are also susceptible to endotoxemia. Bacterial-derived toxins cause endotoxemia by promoting inflammatory processes and immune cell infiltration in different organs and systems while impacting metabolic function by altering lipolysis, mitochondrial activity, and insulin sensitivity. In dairy cows, endotoxins enter the bloodstream after overcoming the defense mechanisms of the epithelial barriers, particularly during common periparturient conditions such as mastitis, metritis, and pneumonia, or after abrupt changes in the gut microbiome. In the bovine AT, endotoxins induce a pro-inflammatory response and stimulate lipolysis in AT, leading to the release of free fatty acids into the bloodstream. When excessive and protracted, endotoxin-induced lipolysis can impair adipocyte's insulin signaling pathways and lipid synthesis. Endotoxin exposure can also induce oxidative stress in AT through the production of reactive oxygen species by inflammatory cells and other cellular components. This review provides insights into endotoxins' impact on AT function, highlighting the gaps in our knowledge of the mechanisms underlying AT dysfunction, its connection with periparturient cows' disease risk, and the need to develop effective interventions to prevent and treat endotoxemia-related inflammatory conditions in dairy cattle.

Tissue distribution of cadmium and its effect on reproduction in Spodoptera exigua

Vegetable fields are often contaminated by heavy metals,and Spodoptera exigua is a major vegetable pest which is stressed by heavy metals mainly by feeding.In this study,cadmium accumulation in the tissues of S.exigua exposed to cadmium and its effects on the growth and development of the parents and the offspring were investigated.Under the stress of different concentrations of cadmium(0.2,3.2,and 51.2 mg kg^(-1)),the cadmium content in each tissue of S.exigua increased in a dose-dependent manner.At the larval stage,the highest cadmium accumulation was found in midgut in all three cadmium treatments,but at the adult stage,the highest cadmium content was found in fat body.In addition,the cadmium content in ovaries was much higher than in testes.When F1S.exigua was stressed by cadmium and the F_(2)generation was not fed a cadmium-containing diet,the larval survival,pupation rate,emergence rate and fecundity of the F_(2)generation were significantly reduced in the 51.2 mg kg^(-1)treatment compared to the corresponding F1generation.Even in the F_(2)generation of the 3.2 mg kg^(-1)treatment,the fecundity was significantly lower than in the parental generation.The fecundity of the only-female stressed treatment was significantly lower than that of the only-male stressed treatment at the 3.2 and 51.2 mg kg^(-1)cadmium exposure levels.When only mothers were stressed at the larval stage,the fecundity of the F_(2)generation was significantly lower than that of the F1generation in the 51.2 mg kg^(-1)treatment,and it was also significantly lower than in the 3.2 and 0.2 mg kg^(-1)treatments.The results of our study can provide useful information for forecasting the population increase trends under different heavy metal stress conditions and for the reliable environmental risk assessment of heavy metal pollution.

The marriage of immunomodulatory,angiogenic,and osteogenic capabilities in a piezoelectric hydrogel tissue engineering scafold for military medicine

Background:Most bone-related injuries to grassroots troops are caused by training or accidental injuries.To establish preventive measures to reduce all kinds of trauma and improve the combat effectiveness of grassroots troops,it is imperative to develop new strategies and scafolds to promote bone regeneration.Methods:In this study,a porous piezoelectric hydrogel bone scafold was fabricated by incorporating polydopamine(PDA)-modified ceramic hydroxyapatite(PDA-hydroxyapatite,PHA)and PDA-modified barium titanate(PDABaTiO_(3),PBT)nanoparticles into a chitosan/gelatin(Cs/Gel)matrix.The physical and chemical properties of the Cs/Gel/PHA scafold with 0–10 wt%PBT were analyzed.Cell and animal experiments were performed to characterize the immunomodulatory,angiogenic,and osteogenic capabilities of the piezoelectric hydrogel scafold in vitro and in vivo.Results:The incorporation of BaTiO_(3) into the scafold improved its mechanical properties and increased self-generated electricity.Due to their endogenous piezoelectric stimulation and bioactive constituents,the prepared Cs/Gel/PHA/PBT hydrogels exhibited cytocompatibility as well as immunomodulatory,angiogenic,and osteogenic capabilities;they not only effectively induced macrophage polarization to M2 phenotype but also promoted the migration,tube formation,and angiogenic differentiation of human umbilical vein endothelial cells(HUVECs)and facilitated the migration,osteodifferentiation,and extracellular matrix(ECM)mineralization of MC3T3-E1 cells.The in vivo evaluations showed that these piezoelectric hydrogels with versatile capabilities significantly facilitated new bone formation in a rat large-sized cranial injury model.The underlying molecular mechanism can be partly attributed to the immunomodulation of the Cs/Gel/PHA/PBT hydrogels as shown via transcriptome sequencing analysis,and the PI3K/Akt signaling axis plays an important role in regulating macrophage M2 polarization.Conclusion:The piezoelectric Cs/Gel/PHA/PBT hydrogels developed here with favorable immunomodulation,angiogenesis,and osteogenesis functions may be used as a substitute in periosteum injuries,thereby offering the novel strategy of applying piezoelectric stimulation in bone tissue engineering for the enhancement of combat efectiveness in grassroots troops.

Data-driven modeling on anisotropic mechanical behavior of brain tissue with internal pressure

Brain tissue is one of the softest parts of the human body,composed of white matter and grey matter.The mechanical behavior of the brain tissue plays an essential role in regulating brain morphology and brain function.Besides,traumatic brain injury(TBI)and various brain diseases are also greatly influenced by the brain's mechanical properties.Whether white matter or grey matter,brain tissue contains multiscale structures composed of neurons,glial cells,fibers,blood vessels,etc.,each with different mechanical properties.As such,brain tissue exhibits complex mechanical behavior,usually with strong nonlinearity,heterogeneity,and directional dependence.Building a constitutive law for multiscale brain tissue using traditional function-based approaches can be very challenging.Instead,this paper proposes a data-driven approach to establish the desired mechanical model of brain tissue.We focus on blood vessels with internal pressure embedded in a white or grey matter matrix material to demonstrate our approach.The matrix is described by an isotropic or anisotropic nonlinear elastic model.A representative unit cell(RUC)with blood vessels is built,which is used to generate the stress-strain data under different internal blood pressure and various proportional displacement loading paths.The generated stress-strain data is then used to train a mechanical law using artificial neural networks to predict the macroscopic mechanical response of brain tissue under different internal pressures.Finally,the trained material model is implemented into finite element software to predict the mechanical behavior of a whole brain under intracranial pressure and distributed body forces.Compared with a direct numerical simulation that employs a reference material model,our proposed approach greatly reduces the computational cost and improves modeling efficiency.The predictions made by our trained model demonstrate sufficient accuracy.Specifically,we find that the level of internal blood pressure can greatly influence stress distribution and determine the possible related damage behaviors.