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Mesenchymal stem cells (MSCs) are commonly used as a source for cellular therapy owing to their strong immunosuppressive and regenerative effects. However, MSCs undergo extensive apoptosis within a short period after transplantation. During apoptosis, MSCs generate several apoptotic extracellular vesicles (MSCs-ApoEVs). MSCs-ApoEVs are rich in miRNomes, metabolites, and proteomes. They are critical intercellular communication mediators that can exert different regulatory effects on recipient cells. MSCs-ApoEVs have been shown to promote regeneration in the skin, hair, bone, muscle, and vascular system, etc. This review describes the production, release, isolation, and functionality of ApoEVs in detail. Furthermore, we summarize the existing mechanisms of MSCs-ApoEVs used for tissue regeneration and evaluate the possible strategies for their clinical application.
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Vesículas Extracelulares , Células-Tronco Mesenquimais , Cicatrização , Células-Tronco Mesenquimais/metabolismo , Terapia Baseada em Transplante de Células e Tecidos , ApoptoseRESUMO
BACKGROUND: The retention volume of autologous fat grafts decreases after transplantation due to limited nutrition infiltration and insufficient blood supply. Structural fat grafts and the 3M (multipoint, multitunnel, and multilayer) injection technique have been considered to improve the survival of grafts; however, it is difficult for surgeons to practice in the clinic because grafts tend to gather into a cluster, especially in large volume fat grafting. Therefore, we hypothesize that prefabricated microparticle fat grafts (PFMG) may improve the retention rate. METHODS: The C57BL/6 mouse fat particles were embedded in growth factor-reduced (GFR)-Matrigel to detect cell migration by immunofluorescence staining in vitro. PFMG was prepared by mixing mouse fat particles and GFR Matrigel in a 1:1 volume ratio and injected subcutaneously into C57BL/6 mice. Fat particles mixed with PBS in equal volume served as control group. The grafts were harvested at 1, 4, 8, and 12 weeks after sacrifice. The retention rate of grafts at each time point was measured, and the structural alterations were detected by SEM. Fat necrosis and blood vessel density were evaluated by histological analysis. RESULTS: CD34+ cells are migrated from the PFMG and formed a tree-like tubular network in the in vitro study. The retention rate was higher in the PFMG group than in the control group at week 12 (38% vs. 30%, p < 0.05). After transplantation, the dissociated structure of fat particles was maintained in PFMG by SEM analysis. Histological analysis of PFMG confirmed less fat necrosis and more blood vessel density in the PFMG group at the early stage than in the control group. The GFR Matrigel was displaced by adipose tissue with time. CONCLUSIONS: In this study, we developed a novel fat grafting method, PFMG that dispersed fat grafts and maintained the structure after transplantation. High volume retention volume of PFMG was achieved by promoting cell migration and vessel regeneration. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .
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Tecido Adiposo , Movimento Celular , Colágeno , Combinação de Medicamentos , Sobrevivência de Enxerto , Laminina , Camundongos Endogâmicos C57BL , Proteoglicanas , Animais , Camundongos , Tecido Adiposo/transplante , Neovascularização Fisiológica/fisiologia , Regeneração/fisiologia , Distribuição Aleatória , Feminino , Modelos AnimaisRESUMO
BACKGROUND: Because of the delicate structure of the adipose tissue, fat necrosis accounts for 43.7% of all complications after autologous fat grafting; however, its regulation remains unclear. OBJECTIVES: The purpose of this study was to examine the role of necroptosis in fat graft remodeling after grafting. METHODS: Clinical fat graft necrosis samples were collected, and the expression levels of the necroptosis marker phosphorylated(p)-MLKL were analyzed. Transcriptome analysis was performed on fat grafts before and 1 week after transplantation in C57BL/6 mouse fat grafting models. Additionally, the in vivo effects of RIPK1 inhibitor Nec-1s or RIPK3 inhibitor GSK'872 on the fat grafting complications, including fat necrosis and fibrosis, were investigated. RESULTS: Necroptosis markers were observed and associated with higher occurrence of fibrosis in clinical fat graft necrosis samples compared to normal fat tissue. Amplification and RNA-Seq were conducted on RNA isolated from fat grafts before and after grafting. MLKL, RIPK1, and RIPK3's expression levels were significantly upregulated in comparison to controls. Higher expression levels of necroptotic RNAs were associated with higher levels of DAMPs, including Cxcl2, HMGB1, S100a8, S100a9, Nlrp3, and IL33, and activated proinflammatory signaling pathways, including the TNF, NF-kappa B, and chemokine signaling pathways. Necroptotic inhibitor Nec-1s and GSK'872 robustly suppressed the p-MLKL expression level and significantly inhibited necroptotic cell death, especially in adipocytes. Moreover, administration of Nec-1s and GSK'872 significantly alleviated fat necrosis and subsequent fibrosis in fat grafts. CONCLUSIONS: Collectively, our study findings highlight the potential therapeutic applications of necroptosis inhibitors in preventing fat necrosis and fibrosis after grafting.
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Adipócitos , Fibrose , Camundongos Endogâmicos C57BL , Necroptose , Proteína Serina-Treonina Quinases de Interação com Receptores , Animais , Necroptose/efeitos dos fármacos , Camundongos , Adipócitos/metabolismo , Adipócitos/efeitos dos fármacos , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Modelos Animais de Doenças , Necrose Gordurosa/prevenção & controle , Necrose Gordurosa/etiologia , Necrose Gordurosa/metabolismo , Necrose Gordurosa/patologia , Humanos , Tecido Adiposo/transplante , Tecido Adiposo/metabolismo , Indóis/farmacologia , Proteínas Quinases/metabolismo , Proteínas Quinases/genética , Imidazóis/farmacologia , Masculino , Feminino , Acrilamidas , SulfonamidasRESUMO
Genetically encoded biosensors based on fluorescent proteins (FPs) are powerful tools for tracking analytes and cellular events with high spatial and temporal resolution in living cells and organisms. Compared with intensiometric readout and ratiometric readout, fluorescence lifetime readout provides absolute measurements, independent of the biosensor expression level and instruments. Thus, genetically encoded fluorescence lifetime biosensors play a vital role in facilitating accurate quantitative assessments within intricate biological systems. In this review, we first provide a concise description of the categorization and working mechanism of genetically encoded fluorescence lifetime biosensors. Subsequently, we elaborate on the combination of the fluorescence lifetime imaging technique and lifetime analysis methods with fluorescence lifetime biosensors, followed by their application in monitoring the dynamics of environment parameters, analytes and cellular events. Finally, we discuss worthwhile considerations for the design, optimization and development of fluorescence lifetime-based biosensors from three representative cases.
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A two-photon excited ratiometric fluorescent pH sensor is reported by combining L-cysteine-protected AuNCs (Cys@AuNCs) with fluorescein isothiocyanate (FITC). Cys@AuNCs were synthesized through a one-step self-reduction route and showed pH-responsive photoluminescence at 650 nm. Benefiting from the opposite pH response of Cys@AuNCs and FITC, the fluorescence ratio (F515 nm/F650 nm) of FITC&Cys@AuNCs provided a large dynamic range of 200-fold for pH measurement in the response interval of pH 5.0-8.0. Based on the excellent two-photon absorption coefficient of Cys@AuNCs, the sensor was expected to achieve sensitive quantitation of pH in living cells under two-photon excitation. In addition, colorimetric biosensing based on enzyme-like metal nanoclusters has attracted wide attention due to their low-cost, simplicity, and practicality. It is crucial to develop high catalytic activity nanozyme from the viewpoint of practical application. The synthesized Cys@AuNCs exhibited excellent photoactivated peroxidase-like activity with high substrate affinity and catalytic reaction rate, promising for rapid colorimetric biosensing of field analysis and the control of catalytic reactions by photostimulation.
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Nanopartículas Metálicas , Peroxidase , Fluoresceína-5-Isotiocianato , Ouro , Peroxidases , Corantes Fluorescentes , Concentração de Íons de HidrogênioRESUMO
BACKGROUND: The role of primary tumor resection in patients with distant metastatic laryngeal carcinoma (DMLC) has not been clarified completely. Thus, we used propensity score matching (PSM) and survival analysis to address this issue. METHODS: The PSM was utilized to avoid selection bias and disproportionate distributions of the confounding factors. Kaplan-Meier estimates and Cox proportional hazard analysis were utilized to evaluate overall survival (OS) and cancer-specific survival (CSS). RESULTS: From the Surveillance, Epidemiology, and End Results Program database, a cohort of 480 patients with DMLC were included. After PSM, the OS and CSS for patients who underwent resection were significantly longer than those without resection (median OS: 19 months vs. 8 months, P < 0.001; median CSS: 19 months vs. 9 months, P = 0.002). Tumor resection significantly prolonged survival of DMLC patients with appropriate demographic and clinical characteristics. In the multivariate analysis, age at diagnosis, race, pathologic subtype, and marital status were found significantly affecting both OS and CSS of patients who underwent surgical resection. Predictive nomograms were developed to help distinguish patients with early mortality potential after surgical resection. CONCLUSIONS: This study is the first one using PSM to assess the role played by surgical resection in DMLC and evaluate the prognostic factor of resected patients. Premised on well controlled postoperative complications, resection could significantly prolong OS and CSS of certain patients.
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Carcinoma , Nomogramas , Humanos , Estimativa de Kaplan-Meier , Pontuação de Propensão , Programa de SEERRESUMO
Introduction: The COVID-19 pandemic had collateral effects on many health systems. Cancer screening and diagnostic tests were postponed, resulting in delays in diagnosis and treatment. This study assessed the impact of the pandemic on screening, diagnostics and incidence of breast, colorectal, lung, and prostate cancer; and whether rates returned to pre-pandemic levels by December, 2021. Methods: This is a cohort study of electronic health records from the United Kingdom (UK) primary care Clinical Practice Research Datalink (CPRD) GOLD database. The study included individuals registered with CPRD GOLD between January, 2017 and December, 2021, with at least 365 days of clinical history. The study focused on screening, diagnostic tests, referrals and diagnoses of first-ever breast, colorectal, lung, and prostate cancer. Incidence rates (IR) were stratified by age, sex, and region, and incidence rate ratios (IRR) were calculated to compare rates during and after lockdown with rates before lockdown. Forecasted rates were estimated using negative binomial regression models. Results: Among 5,191,650 eligible participants, the first lockdown resulted in reduced screening and diagnostic tests for all cancers, which remained dramatically reduced across the whole observation period for almost all tests investigated. There were significant IRR reductions in breast (0.69 [95% CI: 0.63-0.74]), colorectal (0.74 [95% CI: 0.67-0.81]), and prostate (0.71 [95% CI: 0.66-0.78]) cancer diagnoses. IRR reductions for lung cancer were non-significant (0.92 [95% CI: 0.84-1.01]). Extrapolating to the entire UK population, an estimated 18,000 breast, 13,000 colorectal, 10,000 lung, and 21,000 prostate cancer diagnoses were missed from March, 2020 to December, 2021. Discussion: The UK COVID-19 lockdown had a substantial impact on cancer screening, diagnostic tests, referrals, and diagnoses. Incidence rates remained significantly lower than pre-pandemic levels for breast and prostate cancers and associated tests by December, 2021. Delays in diagnosis are likely to have adverse consequences on cancer stage, treatment initiation, mortality rates, and years of life lost. Urgent strategies are needed to identify undiagnosed cases and address the long-term implications of delayed diagnoses.
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Tissue engineering chambers (TECs) have been shown to be useful in regenerating adipose tissue. However, tissue fibrosis caused by the chambers compromises the final volume of the newly formed adipose tissue. Surface modifications can compensate for the lack of biocompatibility of an implant. Tranilast (Tra) is an antifibrotic drug used to treat fibrotic pathologies, including keloids and scleroderma. In this study, a polydopamine-assisted tranilast coating (pDA + Tra) was prepared on a polylactic acid (PLA) chamber to minimize tissue fibrosis and achieve a large volume of fat flap regeneration. The in vitro results showed that, in contrast to a PLA chamber, roughness increased, and the fibroblast adhesion and smooth muscle antibody-positive immunoreactivity decreased in the PLA + pDA + Tra chamber. In addition, pedicled adipose tissue flaps were separated from the back of the rabbit and inserted into each chamber using the classic TEC procedure. After 16 weeks, the marked attenuation of fibrosis and promotion of fat regeneration was observed in the PLA + pDA + Tra chamber in contrast to the PLA chamber. Moreover, in contrast to the PLA chamber, Q-PCR results showed that fibrotic factor TGF-ß was significantly reduced, associated with a remarkable increase in adipogenic differentiation transcription factors PPAR-γ and C/EBPα in the PLA + pDA + Tra chamber after 16 weeks (p < 0.05). Thus, PLA chambers loaded with pDA + Tra on the surface have good biocompatibility, and chemical anti-fibrosis reagents can synergistically reduce fibrosis formation while excellently promoting adipose tissue regeneration.
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The growing concern over heavy metal pollution and its impact on the environment and human health has led to a proliferation of research on the detection and differentiation of heavy metal ions. A novel fluorescent sensor array utilizing only one single Ag-nanoclusters (Ag NCs) was developed for the efficient detection of six metal ions. The Ag NCs probe was prepared by using poly(methyl vinyl ether-alt-maleic acid) (PMVEM) as the ligand and has different fluorescence properties in water and dimethyl sulfoxide (DMSO). The interaction between metal ions and Ag NCs resulted in a characteristic fluorescence variation pattern which was subsequently analyzed using various tree-based machine learning models. We have compared different combinations of classification models and pre-processing methods of which the K-Nearest Neighbors Classifier with the first five linear discriminants has the highest accuracy. Through the integration of concentration models within a tree-based pipeline optimization framework, six unique concentration regression models were selected for each metal ion. In addition, the developed sensor array could identify metal ions in binary mixtures. And it still kept high accuracy for the classification of six target metal ions in river water. In conclusion, the proposed framework was found to be effective in the detection of heavy metal ions in environmental samples, thus providing a promising approach for addressing heavy metal pollution.
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Laryngeal cancer (LC), a highly fatal tumor in the head and neck region, has been the focus of research in recent years. The study of LC has primarily focused on the role of long non-coding RNAs (lncRNAs) in regulating gene expression, as they have emerged as pivotal factors in this biological process. Additionally, a reversible RNA modification called N6-methyladenosine (m6A) has been observed to have a significant impact on gene expression as well. The purpose of this research is to investigate the impact of m6A-related lncRNAs on the prognosis of laryngeal squamous cell carcinoma (LSCC). Specifically, this investigation analyzed the m6A-related regulators' patterns of expression and mutation, encompassing a total of 15 regulators. Drawing upon the expression levels of prognostic m6A-regulated lncRNAs, two distinct lncRNA clusters were identified. Further analysis revealed differentially expressed lncRNAs between these clusters. In addition to studying the expression of lncRNAs, the researchers also examined the distribution of clinical characteristics and the tumor microenvironment (TME) in relation to the identified lncRNA clusters. This provided valuable insights into potential associations between lncRNA expression patterns and the clinical features of LSCC. Through the establishment of a risk model associated with lncRNAs, we were able to further investigate their clinical features, prognosis, and immune status. Additionally, we conducted a separate analysis of LINC00528, a lncRNA associated with smoking, examining its expression, overall survival time, correlated mRNAs, and conducting enrichment of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), as well as determining the sensitivity of related drugs. RT-qPCR results also indicated an increase in LINC00528 expression among smoking LSCC patients. The findings suggest that a high expression level of LINC00528 in LSCC patients may lead to a more favorable prognosis, providing new insights for the management and treatment of LSCC patients, particularly those with high expression of LINC00528. Overall, this research sheds light on the prognostic impact of m6A-regulated lncRNAs in LSCC. The implications of these findings for the advancement of innovative therapeutic approaches for LSCC patients are noteworthy.
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[This corrects the article DOI: 10.3389/fimmu.2022.886374.].
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Fibrosis is defined as the abnormal and excessive deposition of extracellular matrix (ECM) components, which leads to tissue or organ dysfunction and failure. However, the pathological mechanisms underlying fibrosis remain unclear. The inflammatory response induced by tissue injury is closely associated with tissue fibrosis. Recently, an increasing number of studies have linked necroptosis to inflammation and fibrosis. Necroptosis is a type of preprogrammed death caused by death receptors, interferons, Toll-like receptors, intracellular RNA and DNA sensors, and other mediators. These activate receptor-interacting protein kinase (RIPK) 1, which recruits and phosphorylates RIPK3. RIPK3 then phosphorylates a mixed lineage kinase domain-like protein and causes its oligomerization, leading to rapid plasma membrane permeabilization, the release of cellular contents, and exposure of damage-associated molecular patterns (DAMPs). DAMPs, as inflammatory mediators, are involved in the loss of balance between extensive inflammation and tissue regeneration, leading to remodeling, the hallmark of fibrosis. In this review, we discuss the role of necroptotic DAMPs in tissue fibrosis and highlight the inflammatory responses induced by DAMPs in tissue ECM remodeling. By summarizing the existing literature on this topic, we underscore the gaps in the current research, providing a framework for future investigations into the relationship among necroptosis, DAMPs, and fibrosis, as well as a reference for later transformation into clinical treatment.
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Alarminas , Apoptose , Alarminas/metabolismo , Apoptose/fisiologia , DNA , Fibrose , Humanos , Inflamação/patologia , Interferons , Necrose/patologia , RNA , Receptores de Morte CelularRESUMO
Background: Hollowing temples are common in aging Asians. Stromal vascular fraction (SVF) gel is a novel, mechanically processed adipose-derived product containing condensed adipose-derived stem cells and native extracellular matrix, allowing improved fat grafting. The present study evaluated the effectiveness of SVF-gel treatment on temple hollowing. Methods: This prospective, single-center study included an SVF-gel grafting group (n = 34) and a Coleman's fat grafting group (n = 29). Temple contour was assessed using preoperative and postoperative photographs. Temple augmentation was quantified using three-dimensional (3D) technology and an MVS-600 3D scanner system. Patient satisfaction was assessed postoperatively. Results: At 12 months follow-up, the minimal forehead width/forehead width ratio and the width of the temporal peak were increased in both groups (p < 0.05).; and the retention rate (41.2% ± 8.4%) of the SVF-gel group was significantly higher than that of Coleman's fat group (32.6% ± 8.8%; p < 0.05). Moreover, patients in the SVF-gel group reported higher satisfaction scores than those in Coleman's fat group. Conclusions: SVF-gel is effective for temple contouring and augmentation., with increased efficacy compared with Coleman's fat.
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[This corrects the article DOI: 10.3389/fsurg.2022.893219.].
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Diabetes mellitus is the most common metabolic disease associated with impaired wound healing. Recently, Schwann cells (SCs), the glia of the peripheral nervous system, have been suggested to accelerate normal skin wound healing. However, the roles of SCs in diabetic wound healing are not fully understood. In this study, Full-thickness wounds were made in the dorsal skin of C57/B6 mice and db/db (diabetic) mice. Tissue samples were collected at different time points, and immunohistochemical and immunofluorescence analyses were performed to detect markers of de-differentiated SCs, including myelin basic protein, Sox 10, p75, c-Jun, and Ki67. In addition, in vitro experiments were performed using rat SC (RSC96) and murine fibroblast (L929) cell lines to examine the effects of high glucose conditions (50 mM) on the de-differentiation of SCs and the paracrine effects of SCs on myofibroblast formation. Here, we found that, compared with that in normal mice, wound healing was delayed and SCs failed to rapidly activate a repair program after skin wound injury in diabetic mice. Furthermore, we found that SCs from diabetic mice displayed functional impairments in cell de-differentiation, cell-cycle re-entry, and cell migration. In vitro, hyperglycemia impaired RSC 96 cell de-differentiation, cell-cycle re-entry, and cell migration, as well as their paracrine effects on myofibroblast formation, including the secretion of TGF-ß and Timp1. These results suggest that delayed wound healing in diabetes is due in part to a diminished SC repair response and attenuated paracrine effects on myofibroblast formation.
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Objective: This study aims to assess the frequency, bacteriology, biofilm characteristics and management of skin flap infection (SFI) following cochlear implantation (CI). Methods: The study enrolled 1,251 patients receiving CI in the First Affiliated Hospital of Fujian Medical University between August 2001 and March 2021. Scanning electron microscopy (SEM) was utilised to characterise the aetiology of infection. A proposed classification system was applied to optimise treatments for post-operative skin flap infection. Results: After CI, SFI was reported in 16 patients (1.28%) and occurred more frequently in patients under 6 years of age. Of all SFI cases Staphylococcus aureus was the most common pathogen for flap infection, with 8 cases (50%) and bacterial biofilm was evident within the jelly-like substance on the surface of implanted devices in SFI patients. A two-stage classification was proposed to optimise the treatment schemes. Conservative therapy was recommended for stage I cases and surgical treatment for stage II patients. Conclusions: Paediatric patients are more susceptible to SFI after CI, which may be attributed to the formation of bacterial biofilm. The proposed classification can facilitate the management of SFI.
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Implante Coclear , Implantes Cocleares , Infecções Estafilocócicas , Bactérias , Biofilmes , Criança , Implantes Cocleares/efeitos adversos , Implantes Cocleares/microbiologia , Humanos , Complicações Pós-Operatórias/etiologia , Staphylococcus aureusRESUMO
Background: Adipose tissue is an ideal filler material that is widely used for soft tissue defects. But the low survival rate and complications associated with such grafts pose a serious challenge, which limits their clinical application. Adipose tissue is a metabolic diet-responsive tissue; however, the influence of diets on fat grafting remains ambiguous. Methods: We extracted inguinal fat pads from C57/BL6 male mice, and transplanted them into the dorsal region of recipient mice (0.3 ml). Post-fat-grafting, mice (n = 54) were randomized into three groups, namely normal diet (ND), high carbohydrate diet (HC), and high-fat diet (HF). Structural changes were assessed by histological staining. Lipolysis activity and vascular regeneration of grafts on day 30 were analyzed using real-time polymerase chain reaction, immunofluorescence, and western blotting. Results: The grafts of mice on HC and HF diets exhibited significantly fewer oil cysts and larger volume retention (0.18 ± 0.01, 0.21 ± 0.01, and 0.25 ± 0.01 ml, for ND, HC, and HF group, respectively, p < 0.05) on day 90. In comparison, grafts for the mice belonging to the HF groups exhibited higher expression of lipolysis-related genes, including adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and carnitine palmitoyltransferase 1 (CPT1), on day 30. Furthermore, increased infiltration of macrophages (F4/80+) and the higher expression of angiogenesis genes were reported in the HF groups. Conclusion: Altogether, the administration of short-term HF diet remarkably enhanced angiogenesis and improved the quality of fat grafts, which was characterized by fewer oil cysts and higher long-term volume retention. The possible mechanisms may be due to the increased macrophage infiltration, and the promoted angiogenesis in HF grafts.
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Recent developments have evidenced the remarkable achievements of hydrogel combining drugs or growth factors delivery on diabetic chronic wound management. However, these techniques remain unsatisfactory and are impeded by high-cost, complex purification or fabrication, sophisticated drug loading, and lacking versatile therapeutic effects into one platform. Herein, a natural hydrogel is presented through feasible processing of fresh egg white, benefiting from the abundant protein contents and physical crosslinking, the gelation procedure of egg white from diverse species was demonstrated by the presented method, the egg white hydrogel can be kneaded to desired mechanical strength after infiltration of cation solution and directly wrote to well-defined architecture by the 3D printer. Meanwhile, the hydrogel possessed the inherent bioactive elements that stimulated the fibroblasts and adipose tissue-derived stem cells at the aspect of proliferation, migration, and functions without cytotoxicity which featured a similar cell-friendly substrate as Matrigel. Otherwise, the resulting 3D-printed hydrogels realized a proangiogenic effect and enhanced collagen deposition in vivo to promote the recovery of the normal and diabetic chronic wound in the absence of exogenous growth factors. Collectively, this hydrogel platform derived from abundant natural food provides an economical yet highly effective solution for chronic wound healing and may find more therapeutic roles in other biological utilizations and clinical practices.
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Diabetes Mellitus , Hidrogéis , Diabetes Mellitus/tratamento farmacológico , Clara de Ovo , Humanos , Hidrogéis/química , Cicatrização , RedaçãoRESUMO
The reconstruction of large-volume soft tissue defects is a major problem in plastic surgery. Many plastic surgeons have focused on external volume expansion (EVE) because of its capacity to promote regeneration of soft tissues, including breast, subcutaneous fat, and skin. EVE is a minimally invasive and less costly tissue engineering approach that has shown great clinical potential. However, many challenges still need to be addressed before such technology can become a common clinical practice. Basic in vivo and in vitro studies have been performed to determine the possible mechanisms by which EVE promotes tissue regeneration and to design optimized animal models. EVE application was found to facilitate cell proliferation and migration, enhance adipogenesis, improve angiogenesis, and provide available space for soft tissue growth. Understanding the mechanical and chemical signals associated with EVE during tissue regeneration may enable the clinical adaptation of this technology. This article reviews the clinical application of EVE techniques, describes preclinical animal models, and evaluates the possible mechanisms by which EVE induces tissue regeneration. Impact statement The reconstruction of large-volume soft tissue defects is a major problem in plastic surgery. External volume expansion (EVE) is a minimally invasive and less costly tissue engineering approach that has shown promise in clinical applications. This article reviews the clinical application of EVE techniques, describes preclinical animal models, and evaluates the possible mechanisms by which EVE induces tissue regeneration.
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Adipogenia , Tecido Adiposo , Animais , Proliferação de Células , Engenharia Tecidual , CicatrizaçãoRESUMO
BACKGROUND: Fat grafting has been regarded as a promising approach for regenerative therapy. Given the rapidly aging population, better understanding of the effect of age on fat graft outcomes and the underlying mechanisms is urgently needed. METHODS: C57/BL6 mice [old (O, 18-20-month-old) and young (Y, 4-month-old)] were randomized to four fat graft groups [old-to-old (O-O), young-to-young (Y-Y), old-to-young (O-Y), and young-to-old (Y-O)]. Detailed cellular events before and after grafting were investigated by histological staining, RNA sequencing, and real-time polymerase chain reaction. The adipogenic differentiation potential of adipose-derived mesenchymal stem cells (AD-MSCs) from old or young donors was investigated in vitro. Additionally, adipogenesis of AD-MSCs derived from old recipients was evaluated in the culture supernatant of old or young donor fat tissue. RESULTS: After 12 weeks, the volume of fat grafts did not significantly differ between the O-O and O-Y groups or between the Y-Y and Y-O groups, but was significantly smaller in the O-O group than in the Y-O group and in the O-Y group than in the Y-Y group. Compared with fat tissue from young mice, senescence-associated secretory phenotype (SASP) factors were upregulated in fat tissue from old mice. Compared with the Y-O group, adipogenesis markers were downregulated in the O-O group, while SASP factors including interleukin (IL)-6, tumor necrosis factor-α, and IL-1ß were upregulated. In vitro, AD-MSCs from old donors showed impaired adipogenesis compared with AD-MSCs from young donors. Additionally, compared with the culture supernatant of young donor fat tissue, the culture supernatant of old donor fat tissue significantly decreased adipogenesis of AD-MSCs derived from old recipients, which might be attributable to increased levels of SASP factors. CONCLUSIONS: Age has detrimental effects on fat graft outcomes by suppressing adipogenesis of AD-MSCs and upregulating expression of SASP factors, and fat graft outcomes are more dependent on donor age than on recipient age. Thus, rejuvenating fat grafts from old donors or banking younger adipose tissue for later use may be potential approaches to improve fat graft outcomes in older adults.