The Role of Immune Cells and Cytokines in Intestinal Wound Healing

Astragalus polysaccharide: implication for intestinal barrier, anti-inflammation, and animal production

Intestine is responsible for nutrients absorption and plays a key role in defending against various dietary allergens, antigens, toxins, and pathogens. Accumulating evidence reported a critical role of intestine in maintaining animal and human health. Since the use of antibiotics as growth promoters in animal feed has been restricted in many countries, alternatives to antibiotics have been globally investigated, and polysaccharides are considered as environmentally friendly and promising alternatives to improve intestinal health, which has become a research hotspot due to its antibiotic substitution effect. Astragalus polysaccharide (APS), a biological macromolecule, is extracted from astragalus and has been reported to exhibit complex biological activities involved in intestinal barrier integrity maintenance, intestinal microbiota regulation, short-chain fatty acids (SCFAs) production, and immune response regulation, which are critical for intestine health. The biological activity of APS is related to its chemical structure. In this review, we outlined the source and structure of APS, highlighted recent findings on the regulation of APS on physical barrier, biochemical barrier, immunological barrier, and immune response as well as the latest progress of APS as an antibiotic substitute in animal production. We hope this review could provide scientific basis and new insights for the application of APS in nutrition, clinical medicine and health by understanding particular effects of APS on intestine health, anti-inflammation, and animal production.

Effects of dietary supplementation of glycerol monolaurate on laying performance, egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens

The objective of this study was to evaluate the effects of different levels of glycerol monolaurate (GML) on laying performance, egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens. A total of 480 Hy-Line Variety Brown hens (age 54 wk) were randomly assigned to 5 treatments: the control group (basal diet) and 4 GML groups (basal diet supplemented with 100, 200, 300, and 400 mg/kg GML). Each treatment consisted of 8 replicates with 12 hens each and the trial lasted for 8 wk. The results showed that dietary inclusion of GML increased the ADFI in the entire experimental period and the average egg weight in wk 5 to 8 and wk 1 to 8 of the experiment (linear, P < 0.05). Dietary GML addition linearly increased albumen height, Haugh unit and yolk color, and quadratically increased eggshell thickness (P < 0.05). The serum SOD activity, T-AOC and IgG concentrations in the 200 mg/kg GML group, and GSH-Px activity in 200 and 300 mg/kg GML groups were increased, while the MDA concentration in 200 and 300 mg/kg GML groups was decreased than those in the control group (P < 0.05). The jejunal villus height and villus height: crypt depth in 300 mg/kg GML group were higher than that in the control group (P < 0.05). The mRNA expression of TLR4, IL-1β and TNF-α in spleen and jejunum decreased with the increase of dietary GML concentration (linear, P < 0.05). In conclusion, dietary GML supplementation could improve egg quality, antioxidant capacity, intestinal morphology and immune function in late-phase laying hens, and dietary 300 mg/kg GML inclusion is suggested.

Human gut homeostasis and regeneration: the role of the gut microbiota and its metabolites

The healthy human gut is a balanced ecosystem where host cells and representatives of the gut microbiota interact and communicate in a bidirectional manner at the gut epithelium. As a result of these interactions, many local and systemic processes necessary for host functionality, and ultimately health, take place. Impairment of the integrity of the gut epithelium diminishes its ability to act as an effective gut barrier, can contribute to conditions associated to inflammation processes and can have other negative consequences. Pathogens and pathobionts have been linked with damage of the integrity of the gut epithelium, but other components of the gut microbiota and some of their metabolites can contribute to its repair and regeneration. Here, we review what is known about the effect of bacterial metabolites on the gut epithelium and, more specifically, on the regulation of repair by intestinal stem cells and the regulation of the immune system in the gut. Additionally, we explore the potential therapeutic use of targeted modulation of the gut microbiota to maintain and improve gut homeostasis as a mean to improve health outcomes.

Recent Advances in Nanozyme-Based Materials for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a type of chronic inflammatory disorder that interferes with the patient's lifestyle and, in extreme situations, can be deadly. Fortunately, with the ever-deepening understanding of the pathological cause of IBD, recent studies using nanozyme-based materials have indicated the potential toward effective IBD treatment. In this review, the recent advancement of nanozymes for the treatment of enteritis is summarized from the perspectives of the structural design of nanozyme-based materials and therapeutic strategies, intending to serve as a reference to produce effective nanozymes for moderating inflammation in the future. Last but not least, the potential and current restrictions for using nanozymes in IBD will also be discussed. In short, this review may provide a guidance for the development of innovative enzyme-mimetic nanomaterials that offer a novel and efficient approach toward the effective treatment of IBD.

Current Progress of Platelet-Rich Derivatives in Cartilage and Joint Repairs

In recent years, several types of platelet concentrates have been investigated and applied in many fields, particularly in the musculoskeletal system. Platelet-rich fibrin (PRF) is an autologous biomaterial, a second-generation platelet concentrate containing platelets and growth factors in the form of fibrin membranes prepared from the blood of patients without additives. During tissue regeneration, platelet concentrates contain a higher percentage of leukocytes and a flexible fibrin net as a scaffold to improve cell migration in angiogenic, osteogenic, and antibacterial capacities during tissue regeneration. PRF enables the release of molecules over a longer period, which promotes tissue healing and regeneration. The potential of PRF to simulate the physiology and immunology of wound healing is also due to the high concentrations of released growth factors and anti-inflammatory cytokines that stimulate vessel formation, cell proliferation, and differentiation. These products have been used safely in clinical applications because of their autologous origin and minimally invasive nature. We focused on a narrative review of PRF therapy and its effects on musculoskeletal, oral, and maxillofacial surgeries and dermatology. We explored the components leading to the biological activity and the published preclinical and clinical research that supports its application in musculoskeletal therapy. The research generally supports the use of PRF as an adjuvant for various chronic muscle, cartilage, and tendon injuries. Further clinical trials are needed to prove the benefits of utilizing the potential of PRF.

The Influence of Apremilast-Induced Macrophage Polarization on Intestinal Wound Healing

There is compelling evidence suggesting a pivotal role played by macrophages in orchestrating intestinal wound healing. Since macrophages display significant plasticity and heterogeneity, exhibiting an either classically activated (M1-like) or alternatively activated (M2-like) phenotype, they can aggravate or attenuate intestinal wound healing. Growing evidence also demonstrates a causal link between impaired mucosal healing in inflammatory bowel disease (IBD) and defects in the polarization of pro-resolving macrophages. By targeting the switch from M1 to M2 macrophages, the phosphodiesterase-4 inhibitor Apremilast has gained recent attention as a potential IBD drug. However, there is a gap in our current knowledge regarding the impact of Apremilast-induced macrophages' polarization on intestinal wound healing. The THP-1 cells were differentiated and polarized into M1 and M2 macrophages, and subsequently treated with Apremilast. Gene expression analysis was performed to characterize macrophage M1 and M2 phenotypes, and to identify possible target genes of Apremilast and the involved pathways. Next, intestinal fibroblast (CCD-18) and epithelial (CaCo-2) cell lines were scratch-wounded and exposed to a conditioned medium of Apremilast-treated macrophages. Apremilast had a clear effect on macrophage polarization, inducing an M1 to M2 phenotype switch, which was associated with NF-κB signaling. In addition, the wound-healing assays revealed an indirect influence of Apremilast on fibroblast migration. Our results support the hypothesis of Apremilast acting through the NF-κB-pathway and provide new insights into the interaction with fibroblast during intestinal wound healing.

Serum Interleukin 6, Controlling Nutritional Status (CONUT) Score and Phase Angle in Patients with Crohn's Disease

Crohn's disease (CD) is a chronic inflammatory disorder that may occur in any segment of the gastrointestinal tract. Asymptomatic or untreated inflammation along with malnutrition can often coexist in patients with CD, impairing clinical outcomes, therefore the aim of this study was to assess the relationship between inflammation, malnutrition risk and nutritional status in CD patients. Consecutive adult CD outpatients aged 18-65 years were recruited. Disease activity was clinically defined by the Crohn's Disease Activity Index (CDAI), whilst anthropometry and phase angle (PhA) were measured. The Controlling Nutritional Status (CONUT) score was retrospectively calculated for screening malnutrition risk and blood samples were taken. A total of 140 CD patients with a mean age of 38.8 ± 13.9 years and an average weight of 64.9 ± 12.0 kg were included. Serum interleukin (IL)-6 concentration was increased in active-CD patients, unrelated to medical treatment, which was associated with CDAI and PhA. Based on the CONUT score, the prevalence of patients with moderate/severe malnutrition risk (score ≥ 5) was 10%, showing lower age, body mass index and fat mass, but higher IL-6 and IL-1β levels than subjects classified as not at risk (score 0-1). Finally, increased IL-6 levels and reduced PhA values were identified as independent predictors of moderate/severe malnutrition risk (p < 0.05). In conclusion, IL-6 increased in active-CD patients, which was inversely correlated with PhA. Although the CONUT score might be helpful for identifying CD patients at moderate/severe risk of malnutrition, larger studies are needed to verify these results in different settings.

Nr4a1-dependent non-classical monocytes are important for macrophage-mediated wound healing in the large intestine

Introduction

Macrophages play an important role in intestinal wound healing. However, the trajectories from circulating monocytes to gut macrophages are incompletely understood.

Methods

Taking advantage of mice depleted for non-classical monocytes due to deficiency for the transcription factor Nr4a1, we addressed the relevance of non-classical monocytes for large intestinal wound healing using flow cytometry, in vivo wound healing assays and immunofluorescence.

Results

We show that wound healing in Nr4a1-deficient mice is substantially delayed and associated with reduced peri-lesional presence of macrophages with a wound healing phenotype.

Discussion

Our data suggest that non-classical monocytes are biased towards wound healing macrophages. These insights might help to understand, how targeting monocyte recruitment to the intestine can be used to modulate intestinal macrophage functions.

Blood-Based Immune Protein Markers of Disease Progression in Murine Models of Acute and Chronic Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic ailment afflicting millions of people worldwide, with the majority of recognized cases within industrialized countries. The impacts of IBD at the individual level are long-lasting with few effective treatments available, resulting in a large burden on the health care system. A number of existing animal models are utilized to evaluate novel treatment strategies. Two commonly used models are (1) acute colitis mediated by dextran sulphate sodium (DSS) treatment of wild-type mice and (2) chronic colitis mediated by the transfer of proinflammatory T cells into immunodeficient mice. Despite the wide use of these particular systems to evaluate IBD therapeutics, the typical readouts of clinical disease progression vary depending on the model used, which may be reflective of mechanistic differences of disease induction. The most reliable indicator of disease in both models remains intestinal damage which is typically evaluated upon experimental endpoint. Herein, we evaluated the expression profile of a panel of cytokines and chemokines in both DSS and T cell transfer models in an effort to identify a number of inflammatory markers in the blood that could serve as reliable indicators of the relative disease state. Out of the panel of 25 markers tested, 6 showed statistically significant shifts with the DSS model, compared to 11 in the T cell transfer model with IL-6, IL-13, IL-22, TNF-α and IFN-γ being common markers of disease in both models. Our data highlights biological differences between animal models of IBD and helps to guide future studies when selecting efficacy readouts during the evaluation of experimental IBD therapeutics.

Acute Inflammation in Tissue Healing

There are well-established links between acute inflammation and successful tissue repair across evolution. Innate immune reactions contribute significantly to pathogen clearance and activation of subsequent reparative events. A network of molecular and cellular regulators supports antimicrobial and tissue repair functions throughout the healing process. A delicate balance must be achieved between protection and the potential for collateral tissue damage associated with overt inflammation. In this review, we summarize the contributions of key cellular and molecular components to the acute inflammatory process and the effective and timely transition toward activation of tissue repair mechanisms. We further discuss how the disruption of inflammatory responses ultimately results in chronic non-healing injuries.

Loss of autism-candidate CHD8 perturbs neural crest development and intestinal homeostatic balance

Individuals with mutations in CHD8 present with gastrointestinal complaints, yet the underlying mechanisms are understudied. Here, using a stable constitutive chd8 mutant zebrafish model, we found that the loss of chd8 leads to a reduced number of vagal neural crest cells (NCCs), enteric neural and glial progenitors, emigrating from the neural tube, and that their early migration capability was altered. At later stages, although the intestinal colonization by NCCs was complete, we found the decreased numbers of both serotonin-producing enterochromaffin cells and NCC-derived serotonergic neurons, suggesting an intestinal hyposerotonemia in the absence of chd8 Furthermore, transcriptomic analyses revealed an altered expression of key receptors and enzymes in serotonin and acetylcholine signaling pathways. The tissue examination of chd8 mutants revealed a thinner intestinal epithelium accompanied by an accumulation of neutrophils and the decreased numbers of goblet cells and eosinophils. Last, single-cell sequencing of whole intestines showed a global disruption of the immune balance with a perturbed expression of inflammatory interleukins and changes in immune cell clusters. Our findings propose a causal developmental link between chd8, NCC development, intestinal homeostasis, and autism-associated gastrointestinal complaints.

Hypoxia-inducible factor as a bridge between healthy barrier function, wound healing, and fibrosis

The healthy mammalian intestine is lined by a single layer of epithelial cells. These cells provide a selectively permeable barrier to luminal contents and normally do so in an efficient and effective manner. Barrier function in the healthy mucosa is provided via several mechanisms including epithelial junctional complexes, mucus production, as well as mucosal-derived antimicrobial proteins. As tissue metabolism is central to the maintenance of homeostasis in the mucosa, intestinal [Formula: see text] levels are uniquely low due to counter-current blood flow and the presence of the microbiota, resulting in the stabilization of the transcription factor hypoxia-inducible factor (HIF). Ongoing studies have revealed that HIF molds normal intestinal metabolism and is central to the coordination of barrier regulation during both homeostasis and active disease. During acute inflammation, HIF is central to controlling the rapid restitution of the epithelium consistent with normal wound healing responses. In contrast, HIF may also contribute to the fibrostenotic response associated with chronic, nonresolving inflammation. As such, HIF may function as a double-edged sword in the overall course of the inflammatory response. Here, we review recent literature on the contribution of HIF to mucosal barrier function, wound healing, and fibrosis.

Carbon Dioxide Sensing by Immune Cells Occurs through Carbonic Anhydrase 2-Dependent Changes in Intracellular pH

CO₂, the primary gaseous product of respiration, is a major physiologic gas, the biology of which is poorly understood. Elevated CO₂ is a feature of the microenvironment in multiple inflammatory diseases that suppresses immune cell activity. However, little is known about the CO₂-sensing mechanisms and downstream pathways involved. We found that elevated CO₂ correlates with reduced monocyte and macrophage migration in patients undergoing gastrointestinal surgery and that elevated CO₂ reduces migration in vitro. Mechanistically, CO₂ reduces autocrine inflammatory gene expression, thereby inhibiting macrophage activation in a manner dependent on decreased intracellular pH. Pharmacologic or genetic inhibition of carbonic anhydrases (CAs) uncouples a CO₂-elicited intracellular pH response and attenuates CO₂ sensitivity in immune cells. Conversely, CRISPR-driven upregulation of the isoenzyme CA2 confers CO₂ sensitivity in nonimmune cells. Of interest, we found that patients with chronic lung diseases associated with elevated systemic CO₂ (hypercapnia) display a greater risk of developing anastomotic leakage following gastrointestinal surgery, indicating impaired wound healing. Furthermore, low intraoperative pH levels in these patients correlate with reduced intestinal macrophage infiltration. In conclusion, CO₂ is an immunomodulatory gas sensed by immune cells through a CA2-coupled change in intracellular pH.

Evidence for anti-inflammatory effects and modulation of neurotransmitter metabolism by Salvia officinalis L

Background

Cognitive health is of great interest to society, with neuroinflammation and systemic inflammation age-related risk factors that are linked to declines in cognitive performance. Several botanical ingredients have been suggested to have benefits in this area including Salvia officinalis (sage), which has shown anti-inflammatory effects and exhibited promising cognitive improvements in multiple human studies. The current study demonstrates anti-inflammatory effects for S. officinalis across a broad set of in vitro models in human cells, and adds further evidence to support modulation of acetylcholine and monoamine neurostransmitter levels as mechanisms that contribute towards the benefits of the herb on cognitive health.

Methods

The effect of S. officinalis extract on release of multiple cytokines and chemokines was measured in human primary intestinal epithelial cells treated with or without LPS stimulation, and Blood Brain Barrier (BBB) cells in presence or absence of recombinant IL-17A and/or Human IL-17RA/IL-17R Antibody. Antioxidant effects were also assessed in BBB cells incubated with the extract and H₂O₂. The anti-inflammatory effects of S. officinalis extract were further assessed based on clinically-relevant biomarker readouts across 12 human primary cell-based disease models of the BioMAP Diversity PLUS panel.

Results

S. officinalis showed significant attenuation of the release of most cytokines/chemokines into apical media in LPS-stimulated intestinal cells, but small increases in the release of markers including IL-6, IL-8 in basolateral media; where TNF-α was the only marker to be significantly reduced. S. officinalis attenuated the release of CRP and VCAM-1 from BBB cells under IL-17A induced conditions, and also decreased H₂O₂ induced ROS overproduction in these cells. Phenotypic profiling with the BioMAP Diversity PLUS Panel identified additional anti-inflammatory mediators, and based on a similarity search analysis suggested potential mechanistic similarity to caffeic acid and drugs known to inhibit COMT and MAO activity to modulate monoamine metabolism. Subsequent in vitro assessment showed that S. officinalis was able to inhibit the activity of these same enzymes.

Conclusions

S. officinalis extract showed anti-inflammatory effects across multiple human cell lines, which could potentially reduce peripheral inflammation and support cognitive health. S. officinalis extract also showed the ability to inhibit enzymes related to the metabolism of monoamine neurotransmitters, suggesting possible dopaminergic and serotonergic effects acting alongside proposed cholinergic effects to mediate acute cognitive performance benefits previously demonstrated for the extract.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03605-1.

The Role of IL-22 in Wound Healing. Potential Implications in Clinical Practice

Wound healing is a complex process that is mediated and influenced by several cytokines, chemokines, and growth factors. Interleukin-22 (IL-22) is a cytokine that plays a critical role in tissue regeneration. Our study is a systematic review that addressed the implications of IL-22 in the healing of wounds caused by external factors. Thirteen studies were included in our review, most of them being experimental studies. Three clinical studies underlined the potential role of IL-22 in day-to-day clinical practice. IL-22 plays a central role in wound healing, stimulating the proliferation, migration, and differentiation of the cells involved in tissue repair. However, overexpression of IL-22 can cause negative effects, such as keloid scars or peritoneal adhesions. The results of the presented studies are promising, but further research that validates the roles of IL-22 in clinical practice and analyzes its potential implication in surgical healing is welcomed.

Nanoparticles Carrying NF-κB p65-Specific siRNA Alleviate Colitis in Mice by Attenuating NF-κB-Related Protein Expression and Pro-Inflammatory Cellular Mediator Secretion

Ulcerative colitis is a disease that causes inflammation and ulcers in the colon and which is typically recurrent, and NF-κB proteins are important players during disease progression. Here, we assess the impact of silica-coated calcium phosphate nanoparticles carrying encapsulated siRNA against NF-κB p65 on a murine model of colitis. To this end, nanoparticles were injected intravenously (2.0 mg siRNA/kg body weight) into mice after colitis induction with dextran sulfate sodium or healthy ones. The disease activity index, the histopathological impact on the colon, the protein expression of several NF-κB-associated players, and the mediator secretion (colon tissue, blood) were analyzed. We found that the nanoparticles effectively alleviated the clinical and histopathological features of colitis. They further suppressed the expression of NF-κB proteins (e.g., p65, p50, p52, p100, etc.) in the colon. They finally attenuated the local (colon) or systemic (blood) pro-inflammatory mediator secretion (e.g., TNF-α, IFN-β, MCP-1, interleukins, etc.) as well as the leucocyte load of the spleen and mesenteric lymph nodes. The nanoparticle biodistribution in diseased animals was seen to pinpoint organs containing lymphoid entities (appendix, intestine, lung, etc.). Taken together, the nanoparticle-related silencing of p65 NF-κB protein expression could well be used for the treatment of ulcerative colitis in the future.

Glucose but Not Fructose Alters the Intestinal Paracellular Permeability in Association With Gut Inflammation and Dysbiosis in Mice

A causal correlation between the metabolic disorders associated with sugar intake and disruption of the gastrointestinal (GI) homeostasis has been suggested, but the underlying mechanisms remain unclear. To unravel these mechanisms, we investigated the effect of physiological amounts of fructose and glucose on barrier functions and inflammatory status in various regions of the GI tract and on the cecal microbiota composition. C57BL/6 mice were fed chow diet and given 15% glucose or 15% fructose in drinking water for 9 weeks. We monitored caloric intake, body weight, glucose intolerance, and adiposity. The intestinal paracellular permeability, cytokine, and tight junction protein expression were assessed in the jejunum, cecum, and colon. In the cecum, the microbiota composition was determined. Glucose-fed mice developed a marked increase in total adiposity, glucose intolerance, and paracellular permeability in the jejunum and cecum while fructose absorption did not affect any of these parameters. Fructose-fed mice displayed increased circulation levels of IL6. In the cecum, both glucose and fructose intake were associated with an increase in Il13, Ifnγ, and Tnfα mRNA and MLCK protein levels. To clarify the relationships between monosaccharides and barrier function, we measured the permeability of Caco-2 cell monolayers in response to IFNγ+TNFα in the presence of glucose or fructose. In vitro, IFNγ+TNFα-induced intestinal permeability increase was less pronounced in response to fructose than glucose. Mice treated with glucose showed an enrichment of Lachnospiracae and Desulfovibrionaceae while the fructose increased relative abundance of Lactobacillaceae. Correlations between pro-inflammatory cytokine gene expression and bacterial abundance highlighted the potential role of members of Desulfovibrio and Lachnospiraceae NK4A136 group genera in the inflammation observed in response to glucose intake. The increase in intestinal inflammation and circulating levels of IL6 in response to fructose was observed in the absence of intestinal permeability modification, suggesting that the intestinal permeability alteration does not precede the onset of metabolic outcome (low-grade inflammation, hyperglycemia) associated with chronic fructose consumption. The data also highlight the deleterious effects of glucose on gut barrier function along the GI tract and suggest that Desulfovibrionaceae and Lachnospiraceae play a key role in the onset of GI inflammation in response to glucose.

A Mathematical Model of the Dynamics of Cytokine Expression and Human Immune Cell Activation in Response to the Pathogen Staphylococcus aureus

Cell-based mathematical models have previously been developed to simulate the immune system in response to pathogens. Mathematical modeling papers which study the human immune response to pathogens have predicted concentrations of a variety of cells, including activated and resting macrophages, plasma cells, and antibodies. This study aims to create a comprehensive mathematical model that can predict cytokine levels in response to a gram-positive bacterium, S. aureus by coupling previous models. To accomplish this, the cytokines Tumor Necrosis Factor Alpha (TNF-α), Interleukin 6 (IL-6), Interleukin 8 (IL-8), and Interleukin 10 (IL-10) are included to quantify the relationship between cytokine release from macrophages and the concentration of the pathogen, S. aureus, ex vivo. Partial differential equations (PDEs) are used to model cellular response and ordinary differential equations (ODEs) are used to model cytokine response, and interactions between both components produce a more robust and more complete systems-level understanding of immune activation. In the coupled cellular and cytokine model outlined in this paper, a low concentration of S. aureus is used to stimulate the measured cellular response and cytokine expression. Results show that our cellular activation and cytokine expression model characterizing septic conditions can predict ex vivo mechanisms in response to gram-negative and gram-positive bacteria. Our simulations provide new insights into how the human immune system responds to infections from different pathogens. Novel applications of these insights help in the development of more powerful tools and protocols in infection biology.

Circulating miRNA expression over the course of colorectal cancer treatment

Colorectal cancer (CRC) is the third-most common cancer type in males and the second-most common cancer type in females, and has the second-highest overall mortality rate worldwide. Approximately 50% of patients in stage I–III develop metastases, mostly localized to the liver. All physiological conditions occurring in the organism are also reflected in the levels of circulating microRNAs (miRNAs/miRs) in patients. miRNAs are a class of small, non-coding, single-stranded RNAs consisting of 18–25 nucleotides, which have important roles in various cellular processes. The aim of the present study was to evaluate a panel of seven circulating miRNAs (miR-106a-5p, miR-210-5p, miR-155-5p, miR-21-5p, miR-103a-3p, miR-191-5p and miR-16-5p) as biomarkers for monitoring patients undergoing adjuvant treatment of CRC. Total RNA was extracted from the plasma of patients with CRC prior to surgery, in the early post-operative period (n=60) and 3 months after surgery (n=14). The levels of the selected circulating miRNAs were measured with the miRCURY LNA miRNA PCR system and fold changes were calculated using the standard ∆∆Cq method. DIANA-miRPath analysis was used to evaluate the role of significantly deregulated miRNAs. The results indicated significant upregulation of miR-155-5p, miR-21-5p and miR-191-5p, and downregulation of miR-16-5p directly after the surgery. In paired follow-up samples, the most significant upregulation was detected for miR-106a-5p and miR-16-5p, and the most significant downregulation was for miR-21-5p. Pathway analysis outlined the role of the differentially expressed miRNAs in cancer development, but the same pathways are also involved in wound healing and regeneration of intestinal epithelium. It may be suggested that these processes should also be considered in studies investigating sensitive and easily detectable circulating biomarkers for recurrence in patients.

Accelerative effect of topical Zataria multiflora essential oil against infected wound model by modulating inflammation, angiogenesis, and collagen biosynthesis

CONTEXT

Zataria multiflora Boiss (Lamiaceae) essential oil (ZME) is believed to be a bactericide herbal medicine and might alleviate negative effects of infection.

OBJECTIVE

This study evaluates the effects of an ointment prepared from ZME (ZMEO) on infected wounds.

MATERIALS AND METHODS

A full-thickness excisional skin wound was surgically created in each mouse and inoculated with 5 × 10⁷ suspension containing Pseudomonas aeruginosa and Staphylococcus aureus. The BALB/c mice (n = 72) were divided into four groups: (1) negative control that received base ointment (NCG), (2) positive control that daily received Mupirocin^® (MG), (3) therapeutic ointment containing 2% ZMEO and (4) therapeutic ointment containing 4% ZMEO, for 21 days. Wound contraction, total bacterial count, histopathological parameters, antioxidant activity, qRT-PCR analysis for expression of IL-1β, TNF-α, VEGF, IGF-1, TGF-β, IL-10, and FGF-2 mRNA levels were assessed on days 3, 7, and 14 following the wounding.

RESULTS

Topical administration of ZMEO significantly decreased the total bacterial count and wound area and also expression of IL-1β and TNF-α compared to the control groups (p < 0.05) in all days. This could also increase significantly the expression of TGF-β, IL-10 IGF-1, FGF-2, and VEGF, and also angiogenesis, fibroblasts, fibrocytes, epithelialization ratio, and collagen deposition and improve antioxidant status compared to the control group (p < 0.05).

DISCUSSION AND CONCLUSION

ZMEO accelerated the healing process of infected wounds by shortening the inflammatory factors and increasing proliferative phase. Applying ZMEO only and/or in combination with chemical agents for the treatment of wound healing could be suggested.

From Blood to Regenerative Tissue: How Autologous Platelet-Rich Fibrin Can Be Combined with Other Materials to Ensure Controlled Drug and Growth Factor Release

The purpose of this review is to examine the latest literature on the use of autologous platelet-rich fibrin as a drug and growth factor carrier system in maxillofacial surgery. Autologous platelet-rich fibrin (PRF) is a unique system that combines properties such as biocompatibility and biodegradability, in addition to containing growth factors and peptides that provide tissue regeneration. This opens up new horizons for the use of all beneficial ingredients in the blood sample for biomedical purposes. By itself, PRF has an unstable effect on osteogenesis: therefore, advanced approaches, including the combination of PRF with materials or drugs, are of great interest in clinics. The main advantage of drug delivery systems is that by controlling drug release, high drug concentrations locally and fewer side effects within other tissue can be achieved. This is especially important in tissues with limited blood supply, such as bone tissue compared to soft tissue. The ability of PRF to degrade naturally is considered an advantage for its use as a "warehouse" of controlled drug release systems. We are focusing on this concentrate, as it is easy to use in manipulations and can be delivered directly to the surgical site. The target audience for this review are researchers and medical doctors who are involved in the development and research of PRFs further studies. Likewise, surgeons who use PRF in their work to treat patients and who advice patients to take the medicine orally.

Preparation of W/O Hypaphorine-Chitosan Nanoparticles and Its Application on Promoting Chronic Wound Healing via Alleviating Inflammation Block

Chronic wound repair is a common complication in patients with diabetes mellitus, which causes a heavy burden on social medical resources and the economy. Hypaphorine (HYP) has good anti-inflammatory effect, and chitosan (CS) is used in the treatment of wounds because of its good antibacterial effect. The purpose of this research was to investigate the role and mechanism of HYP-nano-microspheres in the treatment of wounds for diabetic rats. The morphology of HYP-NPS was observed by transmission electron microscopy (TEM). RAW 264.7 macrophages were used to assess the bio-compatibility of HYP-NPS. A full-thickness dermal wound in a diabetic rat model was performed to evaluate the wound healing function of HYP-NPS. The results revealed that HYP-NPS nanoparticles were spherical with an average diameter of approximately 50 nm. The cell experiments hinted that HYP-NPS had the potential as a trauma material. The wound test in diabetic rats indicated that HYP-NPS fostered the healing of chronic wounds. The mechanism was through down-regulating the expression of pro-inflammatory cytokines IL-1β and TNF-α in the skin of the wound, and accelerating the transition of chronic wound from inflammation to tissue regeneration. These results indicate that HYP-NPS has a good application prospect in the treatment of chronic wounds.

Surface-Modified Multifunctional Thymol-Loaded Biodegradable Nanoparticles for Topical Acne Treatment

The present work is focused on the development of novel surface-functionalized poly(lactic-co-glycolic acid) nanoparticles loaded with thymol (TH-NPs) for topical administration enhancing thymol anti-inflammatory, antioxidant and wound healing activities against acne. TH-NPs were prepared by solvent evaporation method using different surface functionalization strategies and obtaining suitable physicochemical parameters and a good short-term stability at 4 °C. Moreover, TH-NPs skin penetration and antioxidant activity were assessed in ex vivo pig skin models. Skin penetration of TH-NPs followed the follicular route, independently of the surface charge and they were able to enhance antioxidant capacity. Furthermore, antimicrobial activity against Cutibacterium acnes was evaluated in vitro by the suspension test showing improved antibacterial performance. Using human keratinocyte cells (HaCat), cytotoxicity, cellular uptake, antioxidant, anti-inflammatory and wound healing activities were studied. TH-NPs were non-toxic and efficiently internalized inside the cells. In addition, TH-NPs displayed significant anti-inflammatory, antioxidant and wound healing activities, which were highly influenced by TH-NPs surface modifications. Moreover, a synergic activity between TH-NPs and their surface functionalization was demonstrated. To conclude, surface-modified TH-NPs had proven to be suitable to be used as anti-inflammatory, antioxidant and wound healing agents, constituting a promising therapy for treating acne infection and associated inflammation.

Application of biomaterials in periodontal tissue repair and reconstruction in the presence of inflammation under periodontitis through the foreign body response: Recent progress and perspectives

Periodontitis would cause dental tissue damage locally. Biomaterials substantially affect the surrounding immune microenvironment through treatment-oriented local inflammatory remodeling in dental periodontitis. This remodeling process is conducive to wound healing and periodontal tissue regeneration. Recent progress in understanding the foreign body response (FBR) and immune regulation, including cell heterogeneity, and cell-cell and cell-material interactions, has provided new insights into the design criteria for biomaterials applied in treatment of periodontitis. This review discusses recent progress and perspectives in the immune regulation effects of biomaterials to augment or reconstruct soft and hard tissue in an inflammatory microenvironment of periodontitis.

Depletion of Intestinal Stem Cell Niche Factors Contributes to the Alteration of Epithelial Differentiation in SAMP1/YitFcsJ Mice With Crohn Disease-Like Ileitis

BACKGROUND

SAMP1/YitFcsJ (SAMP1) mice spontaneously develop terminal ileitis resembling human Crohn disease. SAMP1 mice have exhibited alteration of epithelial cell lineage distribution and an overall proliferation of the crypt cell population; however, it has not been evaluated whether epithelial differentiation is impaired because of dysfunction of intestinal stem cells (ISCs) or their niche factors.

METHODS

Using the intestine of SAMP1 mice aged 10 to 14 weeks, morphometric alterations in the crypt-villus architecture, ISCs, crypt cells, and differentiated cells; organoid formation capacity of intestinal crypts; and niche signaling pathways were analyzed and compared with those of age-matched control AKR/J (AKR) mice.

RESULTS

The ileum of SAMP1 mice showed increased depth of intestinal crypts and decreased surface area of the villi compared with those in the ileum of AKR mice. The number of ISCs in the ileal crypts did not differ between SAMP1 and AKR mice; however, the number of Paneth cells decreased and the number of transient amplifying cells increased. The organoid formation rate of the ileal crypts of SAMP1 mice decreased significantly compared with that of AKR mice. The performance of RNA sequencing for intestinal crypts found that the expression of ISC niche factors, such as Wnt3, Dll1, and Dll4, was decreased significantly in the ileal crypts of SAMP1 mice compared with those of AKR mice. Among the ISC niche signals, the Notch signaling-related genes tended to be downregulated. In particular, immunocytochemistry revealed that the expression of Paneth cell-expressing Notch ligand Dll4 was significantly decreased in the intestinal tissue and organoids of SAMP1 mice compared with those of AKR mice.

CONCLUSIONS

Depletion of niche factors for ISCs contributes to the alteration of epithelial differentiation in SAMP1 mice.

Synergistic Action of Diclofenac with Endotoxin-Mediated Inflammation Exacerbates Intestinal Injury in Vitro

Intestinal homeostasis is tightly regulated by the orchestrated actions of a multitude of cell types, including enterocytes, goblet cells, and immune cells. Disruption of intestinal barrier function can increase susceptibility to pathogen invasion and destabilize commensal microbial-epithelial-immune interaction, manifesting in various intestinal and systemic pathologies. However, a quantitative understanding of how these cell types communicate and collectively contribute to tissue function in health and disease is lacking. Here, we utilized a human intestinal epithelial-dendritic cell model and multivariate analysis of secreted factors to investigate the cellular crosstalk in response to physiological and/or pathological cues (e.g., endotoxin, nonsteroidal anti-inflammation drug (NSAID)). Specifically, we demonstrated that treatment with diclofenac (DCF), an NSAID commonly used to treat inflammation associated with acute infection and other conditions, globally suppressed cytokine secretion when dosed in isolation. However, the disruption of barrier function induced by DCF allowed for luminal lipopolysaccharide (LPS) translocation and activation of resident immune cells that overrode the anti-inflammatory influence of DCF. DCF-facilitated inflammation in the presence of LPS was in part mediated by upregulation of macrophage migration inhibitory factor (MIF), an important regulator of innate immunity. However, while neutralization of MIF activity normalized inflammation, it did not lead to intestinal healing. Our data suggest that systems-wide suppression of inflammation alone is insufficient to achieve mucosal healing, especially in the presence of DCF, the target of which, the COX-prostaglandin pathway, is central to mucosal homeostasis. Indeed, DCF removal postinjury enabled partial recovery of intestinal epithelium functions, and this recovery phase was associated with upregulation of a subset of cytokines and chemokines, implicating their potential contribution to intestinal healing. The results highlight the utility of an intestinal model capturing immune function, coupled with multivariate analysis, in understanding molecular mechanisms governing response to microbial factors, supporting application in studying host-pathogen interactions.

Platelet-rich fibrin: Basics of biological actions and protocol modifications

Platelet-rich fibrin (PRF) represents second generation of platelet concentrates, which has gained increasing awareness in recent years for regenerative procedures. This biologic additive is completely autologous, easy to prepare, has minimal expense, and possesses prolonged growth factor release, together with several other advantages over traditionally prepared platelet concentrates. Since its introduction, various protocols for PRF preparation have been proposed with different amounts of growth factors and other biomolecules necessary for wound healing. However, reference data about potential effect of some PRF components on hard and soft tissue healing are still conflicting. The current article intends to clarify the relevant advances about physiological role of certain PRF components and to provide insight into the new developmental approach. Also, this review summarizes the evolution of platelet concentrates and biologic properties of different modifications of PRF procedure.

Similarities between Tumour Immune Response and Chronic Wound Microenvironment: Influence of Mesenchymal Stromal/Stem Cells

Tumours are characterized by a state of chronic inflammation and are regarded as wounds that never heal. Mesenchymal stromal/stem cells (MSCs) are being considered as a possible treatment option. While MSCs can regulate the immune system, migrate to sites of inflammation, and are naturally immune-privileged, there have been contradictory reports on the role of these cells in the tumour microenvironment (TME). Some studies have suggested that MSCs promote tumourigenesis while others have suggested the contrary. To better evaluate the role of MSCs in the TME, it may be helpful to understand the role of MSCs in chronic wounds. Here, we discuss the role of MSCs in chronic wounds and extrapolate this to the TME. Chronic wounds are stuck in the inflammatory phase of wound healing, while in the case of the TME, both the inflammatory and proliferative phases are exploited. MSCs in chronic wounds promote a switch in macrophage phenotype from proinflammatory (M1) to anti-inflammatory (M2), thereby suppressing T, B, and natural killer cells, consequently promoting wound healing. In the case of the TME, MSCs are reported to promote tumorigenesis by suppressing T, B, and natural killer cells in addition to dendritic cells, cytotoxic T cells, and Th1-associated cytokines, thereby promoting tumour growth. Some studies have however suggested that MSCs inhibit tumourigenesis, depending on the source of the MSCs and the specific mediators involved. Therefore, the role of MSCs in the TME appears to be complex and may result in variable outcomes. Compelling evidence to suggest that MSCs are an effective treatment option against tumour progression is lacking.

Human adipose-derived stem cells promote seawater-immersed wound healing via proangiogenic effects

Seawater immersion can increase the damage to skin wounds and produce chronic wounds, and the application of human adipose-derived stem cells can significantly promote healing. However, the mechanism underlying angiogenesis is currently unclear. In this study, we investigated the vascularization effect of human adipose-derived stem cells on the repair of seawater-treated skin wounds and explored the underlying mechanisms using bioinformatics. The results showed that human adipose-derived stem cells differentiated into vascular endothelial cells and promoted seawater-immersed wound vascularization by promoting vascular endothelial cell proliferation and migration. The differentially expressed genes between human adipose-derived stem cells and fibroblasts were identified and analyzed (including via gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment, protein–protein interaction network, and correlation analyses). The genes may promote wound healing by regulating the mechanisms of extracellular matrix remodeling, programmed cell death, inflammation, and vascularization. In conclusion, this study provides novel insights into the use of human adipose-derived stem cells in the regeneration of seawater-immersed skin wounds and chronic wounds.

Intestinal Mucosal Wound Healing and Barrier Integrity in IBD-Crosstalk and Trafficking of Cellular Players

The intestinal epithelial barrier is carrying out two major functions: restricting the entry of potentially harmful substances while on the other hand allowing the selective passage of nutrients. Thus, an intact epithelial barrier is vital to preserve the integrity of the host and to prevent development of disease. Vice versa, an impaired intestinal epithelial barrier function is a hallmark in the development and perpetuation of inflammatory bowel disease (IBD). Besides a multitude of genetic, molecular and cellular alterations predisposing for or driving barrier dysintegrity in IBD, the appearance of intestinal mucosal wounds is a characteristic event of intestinal inflammation apparently inducing breakdown of the intestinal epithelial barrier. Upon injury, the intestinal mucosa undergoes a wound healing process counteracting this breakdown, which is controlled by complex mechanisms such as epithelial restitution, proliferation and differentiation, but also immune cells like macrophages, granulocytes and lymphocytes. Consequently, the repair of mucosal wounds is dependent on a series of events including coordinated trafficking of immune cells to dedicated sites and complex interactions among the cellular players and other mediators involved. Therefore, a better understanding of the crosstalk between epithelial and immune cells as well as cell trafficking during intestinal wound repair is necessary for the development of improved future therapies. In this review, we summarize current concepts on intestinal mucosal wound healing introducing the main cellular mediators and their interplay as well as their trafficking characteristics, before finally discussing the clinical relevance and translational approaches to therapeutically target this process in a clinical setting.

DSS-induced colitis is associated with adipose tissue dysfunction and disrupted hepatic lipid metabolism leading to hepatosteatosis and dyslipidemia in mice

Considering high prevalence of non-alcoholic fatty liver diseases (NAFLD) in patients with inflammatory bowel disease (IBD), this study aimed to elucidate molecular mechanisms for how intestinal inflammatory conditions are causally linked to hepatic steatosis and dyslipidemia. Both younger and older mice treated with acute or chronic dextran sodium sulfate (DSS) developed colitis, which was evidenced by weight loss, colon length shortening, and elevated disease activity index and inflammation score. They also showed decreased expression of intestinal barrier function-related proteins and elevated plasma lipopolysaccharide level, indicating DSS-induced barrier dysfunction and thereby increased permeability. Interestingly, they displayed phenotypes of hepatic fat accumulation and abnormal blood lipid profiles. This DSS-induced colitis-associated lipid metabolic dysfunction was due to overall disruption of metabolic processes including fatty acid oxidation, lipogenesis, lipolysis, reverse cholesterol transport, bile acid synthesis, and white adipose tissue browning and brown adipose tissue thermogenesis, most of which are mediated by key regulators of energy homeostasis such as FGF21, adiponectin, and irisin, via SIRT1/PGC-1α- and LXRα-dependent pathways. Our study suggests a potential molecular mechanism underlying the comorbidity of NAFLD and IBD, which could provide a key to understanding how the two diseases are pathogenically linked and discovering critical therapeutic targets for their treatment.

Understanding intestinal health in nursery pigs and the relevant nutritional strategies

In the modern pig production, pigs are weaned at early age with immature intestine. Dietary and environmental factors challenge the intestine, specifically the jejunum, causing inflammation and oxidative stress followed by destruction of epithelial barrier and villus structures in the jejunum. Crypt cell proliferation increases to repair damages in the jejunum. Challenges to maintain the intestinal health have been shown to be related to changes in the profile of mucosa-associated microbiota in the jejunum of nursery pigs. All these processes can be quantified as biomarkers to determine status of intestinal health related to growth potential of nursery pigs. Nursery pigs with impaired intestinal health show reduced ability of nutrient digestion and thus reduced growth. A tremendous amount of research effort has been made to determine nutritional strategies to maintain or improve intestinal health and microbiota in nursery pigs. A large number of feed additives have been evaluated for their effectiveness on improving intestinal health and balancing intestinal microbiota in nursery pigs. Selected prebiotics, probiotics, postbiotics, and other bioactive compounds can be used in feeds to handle issues with intestinal health. Selection of these feed additives should aim modulating biomarkers indicating intestinal health. This review aims to define intestinal health and introduce examples of nutritional approaches to handle intestinal health in nursery pigs.

Mitochondrial Metabolism in the Intestinal Stem Cell Niche-Sensing and Signaling in Health and Disease

Mitochondrial metabolism, dynamics, and stress responses in the intestinal stem cell niche play a pivotal role in regulating intestinal epithelial cell homeostasis, including self-renewal and differentiation. In addition, mitochondria are increasingly recognized for their involvement in sensing the metabolic environment and their capability of integrating host and microbial-derived signals. Gastrointestinal diseases such as inflammatory bowel diseases and colorectal cancer are characterized by alterations of intestinal stemness, the microbial milieu, and mitochondrial metabolism. Thus, mitochondrial function emerges at the interface of determining health and disease, and failure to adapt mitochondrial function to environmental cues potentially results in aberrant tissue responses. A mechanistic understanding of the underlying role of mitochondrial fitness in intestinal pathologies is still in its infancy, and therapies targeting mitochondrial (dys)function are currently lacking. This review discusses mitochondrial signaling and metabolism in intestinal stem cells and Paneth cells as critical junction translating host- and microbe-derived signals into epithelial responses. Consequently, we propose mitochondrial fitness as a hallmark for intestinal epithelial cell plasticity, determining the regenerative capacity of the epithelium.

Sunitinib malate inhibits intestinal tumor development in male ApcMin/+ mice by down-regulating inflammation-related factors with suppressing β-cateinin/c-Myc pathway and re-balancing Bcl-6 and Caspase-3

Sunitinib is a tyrosine kinase inhibitor for many tumors. Inflammation is one of the most important factors in the development of intestinal tumors. Many inflammation-related factors are regulated by tyrosine kinase receptors. It is reasonable to hypothesize that sunitinib can regulate the development of intestinal tumors by regulating the expression and/or activity of inflammation-related factors. Here, ApcMin/+ male mouse model was used to investigate the effect and mechanism of sunitinib malate against intestinal cancer. Results show that compared to vehicle, after sunitinib malate treatment, overall survival of ApcMin/+ mice was lengthened up to 25 days, with a gain of body weight, reduction of spleen/body weight index, and RBC, WBC and HGC regulated to normal levels of wild type mice, and a number of polyps no less than 1 mm significantly reduced. Meanwhile, in the intestines, the nuclear β-Catenin protein and c-Myc mRNA were both down-regulated, and Bcl-6 was significantly reduced with Caspase-3 up regulated. Furthermore, inflammation-related factors including IL-6, TNF-α, IL-1α, IL-1β and IFN-γ were down-regulated at mRNA levels in the intestines. These results suggest that sunitinib malate can significantly improve the survival status and inhibit intestinal tumor development in male ApcMin/+ mice, through inhibiting inflammation-related factors, while suppressing β-cateinin/c-Myc pathway and re-balancing protein levels of Bcl-6 and Caspase-3.

Short-Term Lincomycin Exposure Depletion of Murine Microbiota Affects Short-Chain Fatty Acids and Intestinal Morphology and Immunity

Lincomycin, as one of the most commonly used antibiotics, may cause intestinal injury, enteritis and other side effects, but it remains unknown whether these effects are associated with microbial changes and the effects of different doses of lincomycin on infants. Here, 21-day old mice were exposed to 1 and 5 g/L lincomycin to explore the effects of lincomycin on the gut microbiota, metabolites and inflammation. Compared to the control mice, 1 g/L lincomycin exposure decreased the body weight gain of mice (p < 0.05). Both 1 and 5 g/L lincomycin exposure reduced the diversity and microbial composition of mice (p < 0.05). Furthermore, 1 and 5 g/L lincomycin reduced the relative concentrations of acetate, propionate, butyrate, valerate, isobutyric acid and isovaleric acid in the colon chyme of mice (p < 0.05). In addition, 5 g/L lincomycin exposure reduced the villus height, crypt depth, and relative expression of TLR2, TLR3, TLR4, IL-18, TNF-α, and p65 in the jejunum of mice (p < 0.05), while 1 g/L lincomycin exposure reduced the relative expression of TLR2, TLR3, TNF-α, and p65 (p < 0.05). Collectively, these results highlight the depletion effect of short-term lincomycin exposure on microbiota and the further regulatory effect on intestinal morphology and immunosuppression in infant mice.

Effects of Wheat Bran Applied to Maternal Diet on the Intestinal Architecture and Immune Gene Expression in Suckling Piglets

Simple Summary

This research was committed to revealing the potential effects of the use of a high percentage of wheat bran (WB) in the sow’s diets on the offspring’s growth and health, by measuring the bodyweight gain, the morphology of the intestine, as well as the expression levels of immune-related genes in the mucosa of the ileum and colon. Results indicate that adding 25% of wheat bran to the sow’s gestation and 14% to the lactation diet can affect the intestinal architecture and the expression of some inflammation genes, to some extent, in the ileal mucosa in the progeny.

Abstract

The strategy of improving the growth and health of piglets through maternal fiber diet intervention has attracted increasing attention. Therefore, 15 sows were conducted to a wheat bran (WB) group, in which the sows’ diets included 25% of WB in gestation and 14% in lactation, and a control (CON) group, in which the sows’ diets at all stages of reproduction did not contain WB. The results show that maternal high WB intervention seems not to have an impact on the growth of the offspring or the villus height of the duodenum, and the ratio of villi/crypts in the duodenum and jejunum were all higher in piglets born from WB sows, which may indicate that WB piglets had a larger absorption area and capacity for nutrients. The peroxisome proliferator-activated receptor gamma (PPARγ) and interleukin 6 (IL6) expression levels were notably upregulated in the ileal mucosa of WB piglets, while no immune-related genes in the colonic mucosa were affected by the maternal WB supplementation. In conclusion, adding a high proportion of wheat bran to the sow’s gestation and lactation diet can affect the intestinal architecture and the expression of some inflammation genes, to some extent, in the ileal mucosa in the progeny.

Preparation and Evaluation of Sustained Release Platelet-Rich Plasma-Loaded Gelatin Microspheres Using an Emulsion Method

The management and treatment of chronic wounds or acute wounds remain a major challenge in modern medicine. The application of autologous platelet-rich plasma (PRP) has become a promising adjuvant therapy to promote wound healing. PRP is derived from centrifuged whole blood to extract concentrated platelets, and a large amount of cytokines and growth factors are released upon activation. These bioactive molecules can enhance angiogenesis and tissue regeneration. Herein, PRP-loaded gelatin microspheres were prepared by the emulsion cross-linking method. Scanning electron microscopy results showed that the prepared microspheres are completely spherical, with an average particle size of 15.95 ± 3.79 μm and having a uniform particle size. Among them, the surface of a single microsphere is smooth and has a microporous structure, which may be the main channel for drug diffusion. Results of drug release measurements show that the prepared microspheres can slowly release the vascular endothelial growth factor for more than 7 days. In vitro cell experiments show that the prepared microspheres can promote proliferation and migration of L929 mouse fibroblast cells. In summary, the prepared PRP-loaded gelatin microspheres with high and long-term activity can provide experimental and theoretical knowledge for the development of the clinical long-acting injectable formulations.

Production and Characterization of an Integrated Multi-Layer 3D Printed PLGA/GelMA Scaffold Aimed for Bile Duct Restoration and Detection

We successfully fabricated artificial bile duct via 3D printing technique which was composed of poly (lactic-co-glycolic acid) (PLGA) and gelatin methacrylate (GelMA). The PLGA-inner layer provided sufficient strength to support the bile duct contraction, the GelMA-outer layer possessed good biocompatibility to provide a good living environment for the cells. Moreover, IKVAV laminin peptide (Ile-Lys-Val-Ala-Val) and ultrasmall superparamagnetic iron oxide (USPIO) were used to regulate scaffold cell adhesion and magnetic resonance imaging (MRI) detection, respectively. After BMSCs co-culture with IKVAV at a certain concentration, the survival rate and adhesion of BMSCs was increased obviously. Meanwhile, the fabricated scaffold exhibited the tensile modulus in the range of 17.19 - 29.05 MPa and the compressive modulus in the range of 0.042 - 0.066 MPa, which could meet the needs of human implantation. In an animal experiment in vivo pig bile duct regeneration, PLGA/GelMA/IKVAV/USPIO duct conduits could promote bile duct regeneration and enhance cytokeratin 19 (CK19) expression. In summary, the composite bile duct scaffold with excellent MRI imaging function and biocompatibility could be used to develop bioactive artificial bile ducts.