Noninvasive induction of angiogenesis in tissues by external suction: sequential optimization for use in reconstructive surgery

Preconditioning Strategies for Improving the Outcome of Fat Grafting

Autologous fat grafting is a common procedure in plastic, reconstructive, and aesthetic surgery. However, it is frequently associated with an unpredictable resorption rate of the graft depending on the engraftment kinetics. This, in turn, is determined by the interaction of the grafted adipose tissue with the tissue at the recipient site. Accordingly, preconditioning strategies have been developed following the principle of exposing these tissues in the pretransplantation phase to stimuli inducing endogenous protective and regenerative cellular adaptations, such as the upregulation of stress-response genes or the release of cytokines and growth factors. As summarized in the present review, these stimuli include hypoxia, dietary restriction, local mechanical stress, heat, and exposure to fractional carbon dioxide laser. Preclinical studies show that they promote cell viability, adipogenesis, and angiogenesis, while reducing inflammation, fibrosis, and cyst formation, resulting in a higher survival rate and quality of fat grafts in different experimental settings. Hence, preconditioning represents a promising approach to improve the outcome of fat grafting in future clinical practice. For this purpose, it is necessary to establish standardized preconditioning protocols for specific clinical applications that are efficient, safe, and easy to implement into routine procedures.

Establishment of Early Blood Perfusion Promotes CXCL12 Expression and Recruits Monocytes/Macrophages in Damaged Adipose Tissue in Mice Model

BACKGROUND

Blood perfusion in the recipient site is important for adipose tissue repair after fat grafting. It delivers host-derived macrophages derived from monocytes in bone marrow to initiate inflammatory reactions and regenerative responses. According to the ability of CXCL12, a stromal cell-derived factor, to recruit monocytes/macrophages, we studied its effect on adipose tissue repair and regeneration under ischemic and normal conditions.

METHODS

Each inguinal fat pad was crushed for 30 seconds with a clamp in mice (n = 35). The left inguinal vessels were divided and cut off (ischemic group), while the right inguinal vessels were kept patent (control group). Seven animals were sacrificed at 1, 3, 7, 14, and 30 days after surgery, and macrophages (Mac2 and CD206) and adipocytes (perilipin) were assessed. Levels of inflammatory factors (interleukin (IL)-1β, IL-6, and tumor necrosis factor-α) and CXCL12 were measured by quantitative PCR.

RESULTS

The number of macrophages was higher in the control group than in the ischemic group at day 3 (10.33 ± 2.40 vs. 1.33 ± 0.33, p = 0.021). The percentage of M2 macrophages was higher in the control group than in the ischemic group at day 7 (p<0.05). The levels of inflammatory factors and CXCL12 were higher in the control group than in the ischemic group at the early stage (p = 0.038).

CONCLUSIONS

Established blood perfusion leads to up-regulation of CXCL12 during adipose tissue repair and regeneration, which may increase recruitment of monocytes to damaged adipose tissue. These findings increase understanding of the cellular events involved in fat graft survival after grafting.

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.

Combined with dynamic serum proteomics and clinical follow-up to screen the serum proteins to promote the healing of diabetic foot ulcer

OBJECTIVE

Non-healing diabetic foot ulcers are a leading cause of disability and death in diabetic patients, which often results in lower limb amputation. This study aimed to investigate the impact of biomarkers on the healing of diabetic foot ulcers by utilizing dynamic serum proteomics and skin proteomic analysis, combined with clinical case follow-up studies.

METHODS

To analyze dynamic serum proteomic changes in four groups, age-matched normal subjects, diabetic patients, pretreatment diabetic foot ulcer patients, and healed diabetic foot ulcer patients were selected. The differential proteins were screened in conjunction with normal and diabetic foot ulcer skin proteomics. In this study, a total of 80 patients with diabetic foot ulcers were enrolled and monitored for 3-6 months during treatment. To verify the significance of the differential proteins, age-matched diabetic patients (240 patients) and healthy controls (160 patients) were included as controls.

RESULTS

Dynamic serum proteomics trend showed that the level of negative regulatory proteins related to endothelial cell migration, angiogenesis, and vascular development was significantly decreased after treatment of diabetic foot ulcer. GO enrichment analysis suggested that differentially expressed proteins were mainly enriched in protein activation cascade, immunoglobulin production, and complement activation. The researchers identified the core proteins APOA1, LPA, and APOA2 through a convergence of serum and skin proteomics screening. Clinical cases further validated that APOA1 levels are decreased in diabetic foot ulcer patients and are correlated with disease severity. In addition, animal experiments showed that APOA1 could promote wound healing in diabetic mice.

CONCLUSIONS

Based on our dynamic proteomics and clinical case studies, our bioinformatic analysis suggests that APOA1 plays a critical role in linking coagulation, inflammation, angiogenesis, and wound repair, making it a key protein that promotes the healing of diabetic foot ulcers.

Fatter Is Better: Boosting the Vascularization of Adipose Tissue Grafts

Adipose tissue resorption after fat grafting is a major drawback in plastic and reconstructive surgery, which is primarily caused by the insufficient blood perfusion of the grafts in the initial phase after transplantation. To overcome this problem, several promising strategies to boost the vascularization and, thus, increase survival rates of fat grafts have been developed in preclinical studies in recent years. These include the angiogenic stimulation of the grafts by growth factors and botulinum neurotoxin A, biologically active gels, and cellular enrichment, as well as the physical and pharmacological stimulation of the transplantation site. To transfer these approaches into future clinical practice, it will be necessary to establish standardized procedures for their safe application in humans. If this succeeds, the surgical outcomes of fat grafting may be markedly improved, resulting in a significant reduction of the physical and psychological stress for the patients.

Applied Usage and Tips of High Stretch Fixation NPWTi-d for Sternal Osteomyelitis

Sternal osteomyelitis is a rare but devastating complication of median sternotomy. To achieve good outcomes, it should be diagnosed early and treated appropriately. Standard treatment involves antibiotics, debridement, and reconstruction with flaps. To prevent flap complications and recurrence, the wound bed must be prepared carefully. One approach, a recent development, is negative pressure wound therapy with instillation and dwell time (NPWTi-d), where suction cycles are interspersed with wound instillation with solutions. NPWTi-d is currently cautioned against for large trunk wounds and cavities because it might alter core body temperature. Here, we report a new NPWTi-d dressing technique that is associated with successful reconstruction in two severe sternal osteomyelitis cases with wound sizes of 29 × 10 and 28 × 8 cm. This "delay-dressing technique" involves manually pulling the wound edges together; inserting a thin strip of dressing foam; applying dressing film strips from one side of the chest wall to the other, thus placing strong stretching tension on the normal skin around the wound; and then applying NPWTi-d. In our cases, we used the V.A.C. Ulta system for 20 and 17 days. The successful reconstruction in both cases may reflect good wound bed preparation and flap preconditioning due to the mechanical stress imposed by NPWTi-d. Thus, this dressing technique with the V.A.C. Ulta system may be an effective treatment option for sternal osteomyelitis cases.

The Use of Infrared Thermography in Determining Timing for Early Pedicle Division of the Preexpanded Bipedicled Visor Flap after Ischemic Preconditioning

Background

The preexpanded bipedicled visor flap, supported by the bilateral superficial temporal vessels, stands as an ideal choice for upper and lower lip reconstruction in males. However, the bilateral tissue bridges after flap transfer caused patients significant cosmetic deformity and psychological burden. Early division of bilateral pedicles reduced the length of hospitalization and expenses. In this study, infrared thermography (IRT) was used to guide the early pedicle division after ischemic preconditioning.

Methods

This study retrospectively analyzed patients who underwent preexpanded bipedicled visor flap surgery from April 2018 to October 2021. Pedicle division was scheduled at two weeks postflap transfer. Ischemic preconditioning was initiated 3-5 days in advance by repeatedly clamping both pedicles. The temperature alteration of the flap and the temperature difference compared to the normal adjacent tissue were evaluated by IRT. The division surgery was not scheduled until the perfusion assessment indicated adequate. This comprised of subjective examination and indocyanine green angiography. The threshold of temperature difference to determine the pedicle division was analyzed based on the temperature changes between the clamps.

Results

A total of 8 male patients successfully conducted the pedicle division without any complications. The delay period after ischemic preconditioning ranged from 14 to 19 days (average 16 days). Through ischemic preconditioning training, the average temperature of the flap gradually increased from 31.85 ± 0.36°C to 33.89 ± 0.50°C, and the temperature difference with the normal surrounding tissues decreased from 2.89 ± 0.30°C to 1.15 ± 0.46°C (95% confidence interval (1.5, 0.8)). The temperature difference stayed unchanged after pedicle division.

Conclusion

Ischemic preconditioning shortens the perioperative period to pedicle division. Monitoring the temperature change reflects the revascularization between the flap and the recipient site, thus guiding the pedicle division. The temperature difference less than 1.5°C after clamping both pedicles can be set as the safe threshold for pedicle division.

An Innovative and Economical Device for Ischemic Preconditioning of the Forehead Flap Prior to Pedicle Division: A Comparative Study

BACKGROUND

 Ischemic preconditioning of the forehead flap prior to pedicle division helps to improve angiogenesis. Clamping the pedicle by a clamped rubber band with vessel forceps is often clinically applied. However, the severe pain and unstable blocking effect influenced the preconditioning process. In this study, we described an innovative device designed for ischemic preconditioning and compared its efficacy with the clamped rubber band.

METHODS

 The device consists of a self-locking nylon cable tie with a buckle and a rubber tube. The rubber tube is fed over the cable tie to act as a soft outer lining and the cable tie is tightened across the pedicle to block the perfusion for ischemic preconditioning. This device and the standard clamped rubber band were applied respectively before division surgery. The constriction effect, reliability, reproducibility, and the patients' pain tolerance were compared.

RESULTS

 A total of 20 forehead flaps were included. The cable tie had less incidence of loosening (7.7% vs. 16.6%, p < 0.05) and maintained the pressure more effectively. The pain score for the nylon cable tie was significantly lower than the clamped rubber band (4.25 ± 1.02 vs. 6.75 ± 1.12, p < 0.05), especially for 10 pediatric patients (4.50 ± 0.85 vs. 8.10 ± 1.20, p < 0.01). All 20 pedicles were successfully divided at 19 to 22 days with no surgical complications.

CONCLUSION

 Compared with the clamped rubber band, the cable tie produces a more reliable and reproducible ischemic preconditioning effect. It is also better tolerated by the patients. Therefore, we recommend using the nylon cable tie as the preferred device for ischemic preconditioning of the forehead flap.

[Research progress of external volume expansion assisted autologous fat grafting for breast reconstruction]

OBJECTIVE

To review the application progress, mechanism, application points, limitations, and oncological safety of external volume expansion (EVE) assisted autologous fat grafting for breast reconstruction and provide a reference for optimizing the design of EVE.

METHODS

Based on the latest relevant articles, the basic experiments and clinical applications of EVE were summarized.

RESULTS

EVE can reduce interstitial fluid pressure, increase blood supply, and promote adipogenic differentiation, thereby benefiting the survival of transplanted fat. EVE assisted autologous fat grafting in clinical practice can improve the retention rate of breast volume and the outcome of breast reconstruction, meanwhile it doesn't increase the risk of local recurrence. But there is no standard parameters for application, and there are many complications and limitations.

CONCLUSION

EVE improves the survival of transplanted fat, but its complications and poor compliance are obvious, so it is urgent to further investigate customized products for breast reconstruction after breast cancer and establish relevant application guidelines.

Recent and Future Strategies of Mechanotherapy for Tissue Regenerative Rehabilitation

Mechanotherapy, the application of various mechanical forces on injured or diseased tissue, is a viable option for tissue regenerative rehabilitation. Recent advances in tissue engineering (i.e., engineered materials and 3D printing) and soft-robotic technologies have enabled systematic and controlled studies to demonstrate the therapeutic impacts of mechanical stimulation on severely injured tissue. Along with innovation in actuation systems, improvements in analysis methods uncovering cellular and molecular landscapes during tissue regeneration under mechanical loading expand our understanding of how mechanical cues are translated into specific biological responses (i.e., stem cell self-renewal and differentiation, immune responses, etc.). Moving forward, the development of diversified actuation systems that are mechanically tissue friendly, easily scalable, and capable of delivering various modes of loading and monitoring functional biomarkers will facilitate systematic and controlled preclinical and clinical studies. Combining these future actuation systems with single-cell resolution analysis of cellular and molecular markers will enable detailed knowledge of underlying biological responses, and optimization of mechanotherapy protocols for specific tissues/injuries. These advancements will enable diverse mechanotherapy therapies in the future.

"Fasting: An Effective Preconditioning Method to Increase Fat Graft Survival"

BACKGROUND

Most preconditioning techniques before fat grafting require external manipulation. Since nutrition is the main factor maintaining the balance of lipogenesis and lipolysis, we hypothesized that fasting before undergoing autologous fat grafting may increase lipolysis and reduce adipocyte size, thereby improving the fat graft survival rate.

METHODS

C57BL/6 mice were divided into 24 h starved or fed groups. Adipose tissue lipolysis, adipogenesis, and angiogenesis-related gene expression, in fat from both groups, were analyzed. The volume and weight of the grafted fat at 4-8 weeks postoperatively were measured using micro-computed tomography. Immunohistochemistry staining and mRNA expression analysis were also performed to evaluate the effect of fasting on fat graft survival.

RESULTS

Fasting decreased adipocyte size by inducing adipose tissue lipolysis. Adipogenesis-related genes were remarkably downregulated while lipolysis-related genes and angiogenesis inducer genes were significantly upregulated in the starved adipose tissue. The mice grafted with the fat from the 24 h starved group had approximately 20% larger volumes and considerably heavier weights than those from the fed group. Increased viable adipocytes and vessels, and reduced macrophages in the fat grafts obtained from the 24 h starved group were also observed.

CONCLUSIONS

Fasting for 24 h before harvesting fat increased the retention volume of fat graft by increasing angiogenesis via VEGF induction. Therefore, fasting would be a novel and reliable preconditioning strategy to improve graft survival in autologous fat grafting.

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.

Skeletal muscle regeneration with robotic actuation-mediated clearance of neutrophils

[Figure: see text].

Salvia miltiorrhiza Injection Promotes the Adipogenic Differentiation of Human Adipose-Derived Stem Cells

BACKGROUND

Autologous fat grafting is a commonly used strategy to repair soft-tissue defects that has shown an approximately 40 percent increase in use in the past 5 years. However, the high reabsorption rates (average, 50 percent) often result in an unsatisfactory outcome. Current approaches aimed at increasing the blood supply of grafted fat have little clinical support. Here, we found that Salvia miltiorrhiza could improve fat graft survival by promoting adipogenic differentiation of adipose-derived stem cells by means of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT-enhancer binding protein alpha (C/EBPα) signaling.

METHODS

Adipose tissue was harvested from the thighs of two women. Adipose-derived stem cells were characterized by flow cytometry (CD29, CD90, and CD105). The samples (2 × 104 cells/liter) were incubated with or without S. miltiorrhiza injection (0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, and 5 g/liter) during adipogenic differentiation. Oil Red O staining, triglyceride content, and adipogenic gene expression (PPARγ and C/EBPα) were performed to detect adipogenic differentiation.

RESULTS

The triglyceride content in the 0.5-g/liter group was increased significantly compared with that in control groups (0.231 ± 0.010, 76.90 percent versus control, p < 0.001, day 9; 0.303 ± 0.010, 91.28 percent versus control, p < 0.001, day 10; 0.361 ± 0.008, 86.65 percent versus control, p < 0.001, day 11). The expression levels of PPARγ and C/EBPα in the 0.5-g/liter group were both increased significantly compared with those in control groups (0.0097 ± 0.0015, 48.1 percent versus control, p < 0.05 for PPARγ; 0.0423 ± 0.003, 112 percent versus control, p < 0.001 for C/EBPα).

CONCLUSIONS

S. miltiorrhiza injection has a positive effect on adipogenesis of adipose-derived stem cells in vitro. The effect of this treatment on improving fat graft survival needs more in vivo research.

Quality and Quantity-Cultured Human Mononuclear Cells Improve Human Fat Graft Vascularization and Survival in an In Vivo Murine Experimental Model

BACKGROUND

Fat graft ischemia impedes us from having satisfying long-term results. The quality and quantity culture is a 1-week cell culture that increases the vasculogenic potential of peripheral blood mononuclear cells (PBMNC). This in vivo murine model investigates whether enrichment with quality and quantity-cultured human mononuclear cells (MNC-QQ) improves the vascularization in the human fat graft and whether this decreases the tissue loss.

METHODS

Human adipose tissue, PBMNC, MNC-QQ, and stromal vascular fraction were prepared. First, PBMNC, MNC-QQ, and stromal vascular fraction were compared in vitro for vasculogenic potential by endothelial progenitor cell colony-forming and culture assays. Second, 0.25-g fat grafts were created with 1 × 106 PBMNC (n = 16), 1 × 106 MNC-QQ (n = 16), 1 × 106 stromal vascular fraction (n = 16), or phosphate-buffered saline as control (n = 16) before grafting in BALB/c nude mice. Grafts were analyzed for weight persistence, vessel formation by CD31 immunohistochemistry, and angiogenic markers by quantitative polymerase chain reaction.

RESULTS

MNC-QQ develop more definitive endothelial progenitor cell colonies and more functional endothelial progenitor cells compared to PBMNC and stromal vascular fraction. Weight persistence after 7 weeks was significantly higher in grafts with MNC-QQ (89.8 ± 3.5 percent) or stromal vascular fraction (90.1 ± 4.2 percent) compared with control (70.4 ± 6.3 percent; p < 0.05). MNC-QQ-enriched grafts had the highest vessel density (96.6 ± 6.5 vessels/mm2; control, 70.4 ± 5.6 vessels/mm2; p < 0.05). MNC-QQ exerted a direct vasculogenic effect through vascular integration and a potential paracrine vascular endothelial growth factor-mediated effect.

CONCLUSION

Quality and quantity-cultured human mononuclear cells containing endothelial progenitor cells stimulate fat graft vascularization and enhance graft survival in a rodent recipient.

Obstruction of the formation of granulation tissue leads to delayed wound healing after scald burn injury in mice

BACKGROUND

Delayed wound healing remains a common but challenging problem in patients with acute or chronic wound following accidental scald burn injury. However, the systematic and detailed evaluation of the scald burn injury, including second-degree deep scald (SDDS) and third-degree scald (TDS), is still unclear. The present study aims to analyze the wound-healing speed, the formation of granulation tissue, and the healing quality after cutaneous damage.

METHODS

In order to assess SDDS and TDS, the models of SDDS and TDS were established using a scald instrument in C57BL/6 mice. Furthermore, an excisional wound was administered on the dorsal surface in mice (Cut group). The wound-healing rate was first analyzed at days 0, 3, 5, 7, 15 and 27, with the Cut group as a control. Then, on the full-thickness wounds, hematoxylin and eosin (H&E) staining, Masson staining, Sirius red staining, Victoria blue staining and immunohistochemistry were performed to examine re-epithelialization, the formation of granulation tissue, vascularization, inflammatory infiltration and the healing quality at different time points in the Cut, SDDS and TDS groups.

RESULTS

The presented data revealed that the wound-healing rate was higher in the Cut group, when compared with the SDDS and TDS groups. H&E staining showed that re-epithelialization, formation of granulation tissue and inflammatory infiltration were greater in the Cut group, when compared with the SDDS and TDS groups. Immunohistochemistry revealed that the number of CD31, vascular endothelial growth factor A, transforming growth factor-β and α-smooth muscle actin reached preferential peak in the Cut group, when compared with other groups. In addition, Masson staining, Sirius red staining, Victoria blue staining, Gordon-Sweets staining and stress analysis indicated that the ratio of collagen I to III, reticular fibers, failure stress, Young's modulus and failure length in the SDDS group were similar to those in the normal group, suggesting that healing quality was better in the SDDS group, when compared with the Cut and TDS groups.

CONCLUSION

Overall, the investigators first administered a comprehensive analysis in the Cut, SDDS and TDS groups through in vivo experiments, which further proved that the obstacle of the formation of granulation tissue leads to delayed wound healing after scald burn injury in mice.

Heme oxygenase‑1 improves the survival of ischemic skin flaps (Review)

Heat shock protein 32 (Hsp32), also known as heme oxygenase‑1 (HO‑1), is an enzyme that exists in microsomes. HO‑1 can be induced by a variety of stimuli, including heavy metals, heat shock, inflammatory stimuli, heme and its derivatives, stress, hypoxia, and biological hormones. HO‑1 is the rate‑limiting enzyme of heme catabolism, which splits heme into biliverdin, carbon monoxide (CO) and iron. The metabolites of HO‑1 have anti‑inflammatory and anti‑oxidant effects, and provide protection to the cardiovascular system and transplanted organs. This review summarizes the biological characteristics of HO‑1 and the functional significance of its products, and specifically elaborates on its protective effect on skin flaps. HO‑1 improves the survival rate of ischemic skin flaps through anti‑inflammatory, anti‑oxidant and vasodilatory effects of enzymatic reaction products. In particular, this review focuses on the role of carbon monoxide (CO), one of the primary metabolites of HO‑1, in flap survival and discusses the feasibility and existing challenges of HO‑1 in flap surgery.

Low Complication Rates Using Closed-Incision Negative-Pressure Therapy for Panniculectomies: A Single-Surgeon, Retrospective, Uncontrolled Case Series

BACKGROUND

Panniculectomies are associated with high complication rates (43 to 70 percent), particularly in patients with obesity, smoking, and diabetes mellitus. Closed-incision negative-pressure therapy can be used postoperatively to support healing by promoting angiogenesis and decreasing tension. The authors hypothesized that using it with panniculectomies would minimize complications, and that a longer duration of therapy would not increase the incidence of complications. The authors also evaluated whether closed-incision negative-pressure therapy malfunction was associated with complications.

METHODS

This retrospective, uncontrolled case series analyzed 91 patients who underwent panniculectomies managed with closed-incision negative-pressure therapy performed by a single surgeon from 2014 to 2018. Patients were followed for 6 months; therapy duration and malfunction were recorded. Patients were placed into therapy duration groups (2 to 7, 8 to 10, or >10 days). Complications managed conservatively were minor and major if they required intervention. Odds ratios were performed with 95 percent confidence intervals and p values.

RESULTS

Mean follow-up was 225.1 days and mean closed-incision negative-pressure therapy duration was 10.5 days. Major complications were reported in five patients (5.5 percent), infections in four (4.4 percent), dehiscence in two (2.2 percent), and seroma in four (4.4 percent). Patients with malfunction [n = 16 (17.6 percent)] were more likely to experience complications (OR, 3.3; p = 0.043). No significant increase in complications was found with therapy duration longer than 10 days, but potentially there is an increased risk of infection (OR, 4.0; p = 0.067).

CONCLUSIONS

Although high complication rates have been associated with panniculectomies, the authors' results show that low complication rates can be achieved with closed-incision negative-pressure therapy. Randomized controlled trials need to be conducted evaluating different therapy systems and the optimal duration of therapy with panniculectomies.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Embryonic stem cell extracts improve wound healing in diabetic mice

AIMS/HYPOTHESIS

Impaired wound healing significantly impacts morbidity and mortality in diabetic patients, necessitating the development of novel treatments to improve the wound healing process. We here investigated the topical use of acellular embryonic stem cell extracts (EXTs) in wound healing in diabetic db/db mice.

METHODS

Wounds were induced in diabetic db/db mice, which were subsequently treated with EXTs, with 3T3 fibroblast cell line protein extracts (3T3XTs) or with saline as a control. Pathology and mechanistic assays were then performed.

RESULTS

The in vivo topical administration of EXTs facilitates wound closure, contraction and re-epithelialization. Moreover, EXTs reduced the number of wound-infiltrating CD45⁺ inflammatory cells and increased the rate of repair and of angiogenesis as compared to controls. Interestingly, the EXT effect was partly enhanced by the use of a collagen-based biocompatible scaffold. In vivo, topical administration of EXTs increased the percentage of regulatory T cells in the wounded tissue, while in vitro EXT treatment reduced T cell-mediated IFN-γ production. Proteomic screening revealed 82 proteins differentially segregating in EXTs as compared to 3T3 extracts, with APEX1 identified as a key player for the observed immunomodulatory effect of EXTs.

CONCLUSIONS

EXTs are endowed with immunoregulatory and anti-inflammatory properties; their use improves wound healing in diabetic preclinical models.

Mitochondrial quality control in cardiac microvascular ischemia-reperfusion injury: New insights into the mechanisms and therapeutic potentials

Thrombolytic therapy and revascularization strategies create a complete recanalization of the occluded epicardial coronary artery in patients with myocardial infarction (MI). However, about 35 % of patients still experience an impaired myocardial reperfusion, which is termed a no-reflow phenomenon mainly caused by cardiac microvascular ischemia-reperfusion (I/R) injury. Mitochondria are essential for microvascular endothelial cells' survival, both because of their roles as metabolic energy producers and as regulators of programmed cell death. Mitochondrial structure and function are regulated by a mitochondrial quality control (MQC) system, a series of processes including mitochondrial biogenesis, mitochondrial dynamics/mitophagy, mitochondrial proteostasis, and mitochondria-mediated cell death. Our review discusses the MQC mechanisms and how they are linked to cardiac microvascular I/R injury. Additionally, we will summarize the molecular basis that results in defective MQC mechanisms and present potential therapeutic interventions for improving MQC in cardiac microvascular I/R injury.

Negative Pressure From an Internal Spiral Tissue Expander Generates New Subcutaneous Adipose Tissue in an In Vivo Animal Model

BACKGROUND

Tissue expanders are widely utilized in plastic surgery. Traditional expanders usually are "inflatable balloons," which are planned to grow additional skin and/or to create space to be filled, for example, with an implant. In very recent years, reports suggest that negative pressure created by an external device (ie, Brava) induces both skin expansion and adipogenesis.

OBJECTIVES

The authors evaluated and assessed the adipogenetic potential of a novel internal tissue expander in an in vivo animal model.

METHODS

New Zealand female rabbits were enrolled in the study. A prototype spiral inner tissue expander was employed. It consisted of a-dynamic conic expander (DCE) with a valve at the end: when empty, it is flat (Archimedean spiral), whereas when filled with a fluid, it takes a conic shape. Inside the conic spiral, a negative pressure is therefore created. DCE is implanted flat under the latissimus dorsi muscle in experimental animals (rabbit) and then filled to reach the conical shape. Animals were investigated with magnetic resonance imaging, histology, and transmission electronic microscopy at 3, 6, and 12 months.

RESULTS

Magnetic resonance imaging revealed a marked increase in newly formed adipose tissue, reaching its highest amount at 12 months after the DCE implantation. Histology confirmed the existence of new adipocytes, whereas transmission electronic microscopy ultrastructure confirmed that most of these new cells were mature adipocytes.

CONCLUSIONS

Tensile stress, associated with negative-pressure expanders, generated newly white subcutaneous adipose tissue.

Macrophage stimulating 1-induced inflammation response promotes aortic aneurysm formation through triggering endothelial cells death and activating the NF-κB signaling pathway

Aortic aneurysm formation is associated with endothelial cells dysfunction through an undefined mechanism. Macrophage stimulating 1 (Mst1) and NF-κB signaling pathway have been found to be related to inflammation response in endothelial cell damage. The goal of our study is to explore the role of Mst1 in regulating endothelial cell viability with a focus on NF-κB signaling pathway and inflammation response. Endothelial cell viability and death were determined via immunofluorescence and ELISA. Agonist of NF-κB signaling pathway and siRNA against Mst1 were used. The results in our study demonstrated that Mst1 transcription and expression were significantly elevated after exposure to oxidative stress in endothelial cells. Once loss of Mst1 through transfection of siRNA (si-Mst1), endothelial cell viability and survival rate were rapidly increased in response to oxidative stress. In addition, we also found that Mst1 controlled inflammation response and mitochondrial function in endothelial cells. Re-activation of NF-κB signaling pathway was followed by an activation of inflammation response and mitochondrial dysfunction, as evidenced by increased expression of inflammation factors and decreased ATP synthesis. Altogether, our results identify Mst1 as the primary factors responsible for endothelial cells dysfunction in aneurysms formation through inducing inflammation response, endothelial apoptosis, and NF-κB signaling pathway activation.

Recipient-Site Preconditioning with Deferoxamine Increases Fat Graft Survival by Inducing VEGF and Neovascularization in a Rat Model

BACKGROUND

The authors hypothesize that ischemic preconditioning of the recipient site with deferoxamine will increase fat graft survival by enhancing angiogenesis in a rat model.

METHODS

Cell viability, tube formation, and mRNA expression were measured in human umbilical vein endothelial cells treated with deferoxamine. A total of 36 rats were then used for an in vivo study. A dose of 100 mg/kg of deferoxamine was injected subcutaneously into the rat scalp every other day for five treatments. On the day after the final injection, the scalp skin was harvested from half the animals to evaluate the effects of deferoxamine on the recipient site. In the remaining animals, inguinal fat tissue was transplanted to the scalp. Eight weeks after transplantation, the grafts were harvested to evaluate the effects of deferoxamine preconditioning on fat graft survival.

RESULTS

In human umbilical vein endothelial cells, treatment with a deferoxamine concentration higher than 400 μM decreased cell viability compared with the control (p = 0.002). Treatment with 100 and 200 μM deferoxamine increased endothelial tube formation (p = 0.001) and mRNA levels of angiogenesis-related factors (p = 0.02). Rat scalps treated with deferoxamine exhibited increased capillary neoformation (p = 0.001) and vascular endothelial growth factor protein expression (p = 0.024) compared with controls. Fat graft volume retention, capillary density (p < 0.001), and adipocyte viability (p < 0.001) in the grafted fat increased when the recipient site was preconditioned with deferoxamine.

CONCLUSION

This study demonstrated that recipient site preconditioning with deferoxamine increases fat graft survival by inducing vascular endothelial growth factor and neovascularization.

Autologous fat graft assisted by stromal vascular fraction improves facial skin quality: A randomized controlled trial

BACKGROUND

Cell-assisted lipotransfer (CAL) promotes the survival of fat grafts with high vascular density and improves skin quality by increasing collagen content. However, no study has quantified the changes on the skin surface, and rigorous methodological evaluations are still lacking.

DESIGN

Fifty patients were recruited and randomly divided into two groups: an experimental group (n = 25) that underwent a stromal vascular fraction (SVF)-assisted fat graft and a control group (n = 25) that underwent fat graft only.

METHODS

The SVF cells were counted, tested in terms of viability, and characterized. The volumes of whole faces were determined by using a 3D scanner and Geomagic software preoperation, immediately after surgery, and 6 months postoperation. Facial skin qualities, including spots, wrinkles, texture, pores, UV spots, brown spots, red areas, and porphyrins, were detected by a VISIA skin detector preoperation and 6 months postoperation. A visual analog scale was used for clinical evaluation.

RESULTS

The cell pellet contained 1-3 × 10⁷/mL of fresh SVF cells. The cell viability exceeded 98%. The immunophenotyping characteristics and stemness were consistent with the features of adipose- derived stem cells (ADSCs). The survival rate of SVF-enriched fat grafts was significantly higher than that of control grafts: 77.6%±11.6% versus 56.2%±9.5% (p<0.001). The VISIA values of wrinkles (19.3 ± 6.6 versus 10.9 ± 5.5, p<0.001) and texture (15.8 ± 7.0 versus 10.3 ± 5.0, p<0.01) were significantly higher in SVF-enriched group than in control group at 6 months postoperation. During long-term follow-up, the majority of patients in both groups were satisfied with the final facial esthetic results.

CONCLUSIONS

Our results demonstrated the positive outcomes of autologous SVF-assisted fat graft in improving facial skin quality and its promising application potential in clinical settings. This study is registered at www. ClinicalTrials.gov, number NCT02923219.

Sirt3 overexpression alleviates hyperglycemia-induced vascular inflammation through regulating redox balance, cell survival, and AMPK-mediated mitochondrial homeostasis

Context: Sirtuin-3 (Sirt3), a NAD-dependent deacetylase, has been reported to be involved in many biological processes.Objective: The present study aimed to investigate the effect and mechanism of Sirt3 on diabetic mice and human umbilical vein endothelial cells (HUVECs) under high glucose (HG) condition.Materials and methods: HUVECs were cultured under HG and inflammation pathway was determined via qPCR, western blots, and immunofluorescence.Results: Sirt3 expression was reduced in the progression of diabetic nephropathy. Overexpression of Sirt3 sustains renal function and retard the development of diabetic nephropathy. Mechanistically, Sirt3 overexpression attenuated hyperglycemia-mediated endothelial cells apoptosis in kidney. Besides, Sirt3 overexpression repressed oxidative injury and blocked caspase-9-related apoptosis pathway. Moreover, we found that Sirt3 overexpression was associated with AMPK activation and the latter elevates PGC1α-related mitochondrial protective system, especially mitochondrial autophagy. Loss of opa1 and/or inhibition of AMPK could depress mitochondrial autophagy and exacerbates mitochondrial function, finally contributing to the death of human renal mesangial cells.Conclusions: Our results demonstrated the beneficial effects of Sirt3 in the progression of diabetic nephropathy. Increased Sirt3-activated AMPK pathway, augments PGC1α-related mitochondrial protective system, sustained redox balance and closed caspase-9-involved apoptosis pathway in the setting of diabetic nephropathy.

Therapeutic effects of bone mesenchymal stem cells on oral and maxillofacial defects: a novel signaling pathway involving miR-31/CXCR4/Akt axis

Context: Although bone mesenchymal stem cells (BMSCs) have been used for the treatment of oral and maxillofacial defects, the survival rate and limited proliferation reduces the therapeutic efficiency of BMSC.Objective: The aim of our study is to explore the role of miR-31 in regulating survival, proliferation, and migration of BMSC in vitro.Materials and methods: LPS was used in vitro to induce BMSC damage and then miR-31 was used to incubate with BMSC. Subsequently, BMSC proliferation, survival, and migration were determined via ELISA, qPCR, western blots, and immunofluorescence.Results: The expression of miR-31 was downregulated in response to LPS stress. Interestingly, supplementation of miR-31 could reverse the survival, proliferation and migration of BMSC under LPS. Mechanically, miR-31 treatment inhibited the activation of caspase, and thus promoted BMSC survival. Besides, miR-31 upregulated the genes related to cell proliferation, an effect that was followed by an increase in the levels of migratory factors. Further, we found that miR-31 treatment activated the CXCR4/Akt pathway and blockade of CXCR4/Akt could abolish the beneficial effects of miR-31 on BMSC proliferation, survival, and migration.Conclusions: miR-31 could increase the therapeutic efficiency of BMSC via the CXCR4/Akt pathway.

Tissue-Engineered Soft-Tissue Reconstruction Using Noninvasive Mechanical Preconditioning and a Shelf-Ready Allograft Adipose Matrix

BACKGROUND

Adipose tissue defects leading to severe functional (disability) and morphologic (disfigurement) morbidity are often treated in plastic surgery with fat grafting, which can be limited by resorption, necrosis, and cyst formation. This study aimed to assess whether adipose scaffolds could provide an environment for in situ autologous fat grafting, and to study whether adipose cell migration and proliferation (adipogenesis) within scaffolds could be enhanced by preliminarily increasing the vascularity (preconditioning) of the surrounding tissue receiving the scaffolds.

METHODS

Using an established rodent model of subcutaneous tissue/scaffold grafting, the authors tested the potential of a human-derived, shelf-ready, injectable, decellularized allograft adipose matrix to reconstruct soft-tissue defects when used in combination with noninvasive mechanical (suction-induced) skin preconditioning.

RESULTS

Combined use of the allograft adipose matrix and noninvasive skin preconditioning significantly improved long-term volume retention (50 to 80 percent higher at a 12-week follow-up) and histologic quality of reconstructed tissues compared with standard of care (autologous adipose grafts). The components of the allograft adipose matrix supported adipogenesis and angiogenesis. Combining the allograft adipose matrix with living adipose grafts mitigated negative outcomes (lower long-term volume retention, higher presence of cystic-like areas).

CONCLUSIONS

This study suggests that the synergistic use of the allograft adipose matrix and noninvasive tissue preconditioning provides an effective solution for improving fat grafting. These strategies can easily be tested in clinical trials and could establish the basis for a novel therapeutic paradigm in reconstructive surgery.

Pretreatment of bone mesenchymal stem cells with miR181-c facilitates craniofacial defect reconstruction via activating AMPK-Mfn1 signaling pathways

Context: Bone mesenchymal stem cells (BMSC)-based regenerative therapy is critical for the craniofacial defect reconstruction. However, oxidative stress micro-environment after transplantation limits the therapeutic efficiency of BMSC. The miR-181c has been found to be associated with cell survival and proliferation. Objective: Herein, we investigated whether prior miR-181c treatment promoted BMSC proliferation and survival under oxidative stress injury. Materials and methods: Cells were treated with hydrogen peroxide (H₂O₂) and then cell viability was determined via MTT assay, TUNEL staining and ELISA. Western blotting and immunofluorescence assay were used to detect those alterations of mitochondrial function. Results: H₂O₂ treatment reduced BMSC viability and this effect could be reversed via additional supplementation of miR181-c. Mechanistically, oxidative stress increased cell apoptosis, augmented caspase-3 activity, promoted reactive oxygen species (ROS) synthesis, impaired mitochondrial potential, and induced mitochondrial dynamics imbalance. However, miR-181c pretreatment reversed these effects of oxidative stress on BMSC. Moreover, miR-181c treatment improved BMSC proliferation, migration and paracrine, which are very important for craniofacial reconstruction. In addition, we identified that AMPK-Mfn1 axis was the direct targets of miR-181c in BMSC. Mfn1 silencing impaired the protective effects miR-181c on BMSC viability and proliferation under oxidative stress environment. Conclusions: Collectively, our results indicate that miR-181c participates in oxidative stress-mediated BMSC damage by modulating the AMPK-Mfn1 signaling pathway, suggesting miR-181c-AMPK-Mfn1 axis may serves as novel therapeutic targets to facilitate craniofacial defect reconstruction.

Efficacy of an external volume expansion device and autologous fat grafting for breast reconstruction following breast conserving surgery and total mastectomy: Small improvements in quality of life found in a prospective cohort study

BACKGROUND

Although autologous fat grafting (AFG) for breast reconstruction is feasible, the best methods have yet to be established. This study aimed to assess the efficacy of fat grafting using an external expansion device for complete breast reconstruction post breast cancer surgery hypothesizing that it would improve quality of life.

METHODS

A prospective cohort study was conducted in women who had undergone breast cancer surgery and complete reconstruction using AFG. An external expansion device was used previously (as per Miami protocol) to a single-stage AFG. Quality of life outcomes were determined using the validated BREAST-Q questionnaire, and 3D laser and magnetic resonance imaging scan were used to measure fat graft retention.

RESULTS

Twenty-six participants were recruited, with seven withdrawing. The remaining 19 women were compliant with external expander use. The mean volume of AFG was 270.4 mL (98-490 mL) with a mean of 48.8% retained at 12 months following injection. Symmetry improved but did not meet the acceptable symmetry ratio of 0.8. Nine patients (47.3%) noted increased skin elasticity and softening of areas of scarring. Skin irritation occurred in 11 out of 19 patients. Mean BREAST-Q scores improved significantly in the domains of satisfaction with breast (40 vs. 49, p < 0.001), psychosocial well-being (55 vs. 68, p < 0.001), physical well-being abdomen (73 vs. 87, p < 0.001), and sexual well-being (41 vs, 48, p < 0.001).

CONCLUSION

Improved quality of life and breast volume increase were achieved following external expansion and AFG. However, breast fat engraftment retention was similar to that reported in previous studies using fat grafting alone.

Proinflammation effect of Mst1 promotes BV-2 cell death via augmenting Drp1-mediated mitochondrial fragmentation and activating the JNK pathway

Inflammation has been increasingly studied as part of the pathophysiology of neurodegenerative diseases. Mammalian Ste20-like kinase 1 (Mst1), a key factor of the Hippo pathway, is connected to cell death. Unfortunately, little study has been performed to detect the impact of Mst1 in neuroninflammation. The results indicated that Mst1 expression was upregulated because of LPS treatment. However, the loss of Mst1 sustained BV-2 cell viability and promoted cell survival in the presence of LPS treatment. Molecular investigation assay demonstrated that Mst1 deletion was followed by a drop in the levels of mitochondrial fission via repressing Drp1 expression. However, Drp1 adenovirus transfection reduced the protective impacts of Mst1 knockdown on mitochondrial stress and neuronal dysfunction. Finally, our results illuminated that Mst1 affected Drp1 content and mitochondrial fission in a JNK-dependent mechanism. Reactivation of the JNK axis inhibited Mst1 knockdown-mediated neuronal protection and mitochondrial homeostasis. Altogether, our results indicated that Mst1 upregulation and the activation of JNK-Drp1-mitochondrial fission pathway could be considered as the novel mechanism regulating the progression of neuroninflammation. This finding would pave a new road for the treatment of neurodegenerative diseases via modulating the Mst1-JNK-Drp1-mitochondrial fission axis.

Hippo/Mst1 overexpression induces mitochondrial death in head and neck squamous cell carcinoma via activating β-catenin/Drp1 pathway

Mammalian Ste20-like kinase 1 (Mst1) is associated with cell apoptosis. In the current study, we explored the regulatory effects of Mst1 on squamous cell carcinoma of the head and neck (SCCHN) in vitro. SCCHN Cal27 cells and Tu686 cells were transfected with adenovirus-loaded Mst1 to detect the role of Mst1 in cell viability. Then, siRNA against Drp1 was transfected into cells to evaluate the influence of mitochondrial fission in cancer survival. Our data illustrated that Mst1 overexpression promoted SCCHN Cal27 cell and Tu686 cell death via activating mitochondria-related apoptosis. Cells transfected with adenovirus-loaded Mst1 have increased expression of DRP1 and higher DRP1 promoted mitochondrial fission. Active mitochondrial fission mediated mitochondrial damage, as evidenced by increased mitochondrial oxidative stress, decreased mitochondrial energy production, and reduced mitochondrial respiratory complex function. Moreover, Mst1 overexpression triggered mitochondria-dependent cell apoptosis via DRP1-related mitochondrial fission. Further, we found that Mst1 overexpression controlled mitochondrial fission via the β-catenin/DRP1 pathways; inhibition of β-catenin and/or knockdown of DRP1 abolished the pro-apoptotic effects of Mst1 overexpression on SCCHN Cal27 cells and Tu686 cells, leading to the survival of cancer cells in vitro. In sum, our results illustrate that Mst1/β-catenin/DRP1 axis affects SCCHN Cal27 cell and Tu686 cell viability via controlling mitochondrial dynamics balance. This finding identifies Mst1 activation might be an effective therapeutic target for the treatment of SCCHN.

Mst1 deletion reduces hyperglycemia-mediated vascular dysfunction via attenuating mitochondrial fission and modulating the JNK signaling pathway

Diabetes is a leading cause of microvascular complications, such as nephropathy and retinopathy. Recent studies have proposed that hyperglycemia-induced endothelial cell dysfunction is modulated by mitochondrial stress. Therefore, our experiment was to detect the upstream mediator of mitochondrial stress in hyperglycemia-treated endothelial cells with a focus on macrophage-stimulating 1 (Mst1) and mitochondrial fission. Our data illuminated that hyperglycemia incubation reduced cell viability, as well as increased apoptosis ratio in endothelial cell, and this alteration seemed to be associated with Mst1 upregulation. Inhibition of Mst1 via transfection of Mst1 siRNA into an endothelial cell could sustain cell viability and maintain mitochondrial function. At the molecular levels, endothelial cell death was accompanied with the activation of mitochondrial oxidative stress, mitochondrial apoptosis, and mitochondrial fission. Genetic ablation of Mst1 could reduce mitochondrial oxidative injury, block mitochondrial apoptosis, and repress mitochondrial fission. Besides, we also found Mst1 triggered mitochondrial dysfunction as well as endothelial cell damage through augmenting JNK pathway. Suppression of JNK largely ameliorated the protective actions of Mst1 silencing on hyperglycemia-treated endothelial cells and sustain mitochondrial function. The present study identifies Mst1 as a primary key mediator for hyperglycemia-induced mitochondrial damage and endothelial cell dysfunction. Increased Mst1 impairs mitochondrial function and activates endothelial cell death via opening mitochondrial death pathway through JNK.

TrxR2 overexpression alleviates inflammation-mediated neuronal death via reducing the oxidative stress and activating the Akt-Parkin pathway

Neuronal death caused by inflammatory cytokine-mediated neuroinflammation is being extensively explored. Thioredoxin reductase (TrxR) 2 is a novel mediator of inflammation response. In the current study, we focus on the mechanisms of TrxR2 overexpression in inflammation-mediated neuronal death. LPS was used to induce neuroinflammation in N2a cells in vitro. Adenovirus-loaded TrxR2 was transfected into N2a cells to up-regulate TrxR2 expression. Then, cell viability was determined via MTT assay and TUNEL assay. Apoptosis was measured via western blotting and ELISA. Oxidative stress was detected via ELISA and flow cytometry. A pathway inhibitor was used to verify the role of the Akt-Parkin pathway in the LPS-mediated N2a cell death in the presence of TrxR2 overexpression. With the help of immunofluorescence assay and western blotting, we found that TrxR2 expression was significantly reduced in response to LPS treatment, and this effect was associated with N2a cell death via apoptosis. At the molecular level, TrxR2 overexpression elevated the activity of the Akt-Parkin pathway, as evidenced by the increased expression of p-Akt and Parkin. Interestingly, inhibition of the Akt-Parkin pathway abolished the regulatory effect of TrxR2 on LPS-treated N2a cells, as evidenced by the decreased cell viability and increased apoptotic ratio. Besides, TrxR2 overexpression also reduced oxidative stress, inflammation factor transcription and mitochondrial apoptosis. However, inhibition of Akt-Parkin axis abrogated the protective effects of TrxR2 on redox balance, mitochondrial performance and cell survival. LPS-mediated neuronal death was linked to a drop in TrxR2 overexpression and the inactivation of the Akt-Parkin pathway. Overexpression of TrxR2 sustained mitochondrial function, inhibited oxidative stress, repressed inflammation response, and blocked mitochondrial apoptosis, finally sending a pro-survival signal for the N2a cells in the setting of LPS-mediated inflammation environment.

Sirt3 modulate renal ischemia-reperfusion injury through enhancing mitochondrial fusion and activating the ERK-OPA1 signaling pathway

Mitochondrial fusion is linked to heart and liver ischemia-reperfusion (IR) insult. Unfortunately, there is no report to elucidate the detailed influence of mitochondrial fusion in renal IR injury. This study principally investigated the mechanism by which mitochondrial fusion protected kidney against IR injury. Our results indicated that sirtuin 3 (Sirt3) was inhibited after renal IR injury in vivo and in vitro. Overexpression of Sirt3 improved kidney function, modulated oxidative injury, repressed inflammatory damage, and reduced tubular epithelial cell apoptosis. The molecular investigation found that Sirt3 overexpression attenuated IR-induced mitochondrial damage in renal tubular epithelial cells, as evidenced by decreased reactive oxygen species production, increased antioxidants sustained mitochondrial membrane potential, and inactivated mitochondria-initiated death signaling. In addition, our information also illuminated that Sirt3 maintained mitochondrial homeostasis against IR injury by enhancing optic atrophy 1 (OPA1)-triggered fusion of mitochondrion. Inhibition of OPA1-induced fusion repressed Sirt3 overexpression-induced kidney protection, leading to mitochondrial dysfunction. Further, our study illustrated that OPA1-induced fusion could be affected through ERK; inhibition of ERK abolished the regulatory impacts of Sirt3 on OPA1 expression and mitochondrial fusion, leading to mitochondrial damage and tubular epithelial cell apoptosis. Altogether, our results suggest that renal IR injury is closely associated with Sirt3 downregulation and mitochondrial fusion inhibition. Regaining Sirt3 and/or activating mitochondrial fission by modifying the ERK-OPA1 cascade may represent new therapeutic modalities for renal IR injury.

Mst1 contributes to nasal epithelium inflammation via augmenting oxidative stress and mitochondrial dysfunction in a manner dependent on Nrf2 inhibition

Nasal epithelium inflammation plays an important role in transmitting and amplifying damage signals for the lower airway. However, the molecular basis of nasal epithelium inflammation damage has not been fully addressed. Mst1 is reported to modulate inflammation via multiple effects. Thus, the aim of our study is to understand the pathological mechanism underlying Mst1-related nasal epithelium inflammation in vitro. Our result indicated that Mst1 expression was rapidly increased in response to tumor necrosis factor-α (TNF-α) treatment in vitro and this effect was a dose-dependent manner. Interestingly, knockdown of Mst1 via transfecting small interfering RNA markedly reversed cell viability in the presence of TNF-α. Further, we found that Mst1 deficiency reduced cellular oxidative stress and attenuated mitochondrial dysfunction, as evidenced by reversed mitochondrial complex-I activity, decreased mitochondrial permeability transition pore opening rate, and stabilized mitochondrial membrane potential. Besides, we found that Nrf2 expression was increased after deletion of Mst1 whereas silencing of Nrf2 abolished the protective effects of Mst1 deletion on nasal epithelium survival and mitochondrial homeostasis. Moreover, Nrf2 overexpression also protected nasal epithelium against TNF-α-induced inflammation damage. Altogether, our data confirm that the Mst1 activation and Nrf2 downregulation seem to be the potential mechanisms responsible for the inflammation-mediated injury in nasal epithelium via mediating mitochondrial damage and cell oxidative stress.

Mst1 overexpression combined with Yap knockdown augments thyroid carcinoma apoptosis via promoting MIEF1-related mitochondrial fission and activating the JNK pathway

Background

Cancer cell viability is strongly modulated by the Hippo pathway, which includes mammalian STE20-like protein kinase 1 (Mst1) and yes-associated protein (Yap). Although the roles of Mst1 and Yap in thyroid carcinoma cell death have been fully addressed, no study has determined whether differential modification of Mst1 and Yap could further suppress thyroid carcinoma progression. The aim of our study was to explore the antiapoptotic effects exerted by combined Mst1 overexpression and Yap knockdown in thyroid carcinoma MDA-T32 cells in vitro.

Methods

Mst1 adenovirus and Yap shRNA were transfected into MDA-T32 cells to overexpress Mst1 and inhibit Yap, respectively. Cell viability and death were determined via an MTT assay, a TUNEL assay and western blotting. Mitochondrial function, mitochondrial fission and pathway studies were performed via western blotting and immunofluorescence.

Results

The results of our study showed that combined Mst1 overexpression and Yap knockdown further augmented MDA-T32 cell death by mediating mitochondrial damage. In addition, cancer cell migration and proliferation were suppressed by combined Mst1 overexpression and Yap knockdown. At the molecular level, mitochondrial membrane potential, ATP production, respiratory function, and caspase-9-related apoptosis were activated by combined Mst1 overexpression and Yap knockdown. Further, we found that fatal mitochondrial fission was augmented by combined Mst1 overexpression and Yap knockdown in a manner dependent on the JNK-MIEF1 pathway. Inhibition of JNK-MIEF1 pathway activity abolished the proapoptotic effects exerted by Mst1/Yap on MDA-T32 cells.

Conclusions

Taken together, our data suggest that Mst1 activation and Yap inhibition coordinate to augment thyroid cancer cell death by controlling the JNK-MIEF1-mitochondria pathway, suggesting that differential regulation of the core Hippo pathway components is potentially a novel therapeutic tool for the treatment of thyroid cancer.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0860-8) contains supplementary material, which is available to authorized users.

Mitochonic acid-5 attenuates TNF-α-mediated neuronal inflammation via activating Parkin-related mitophagy and augmenting the AMPK-Sirt3 pathways

Mitochondrial dysfunction has been found to be associated with neuronal inflammation; however, no effective drug is available to attenuate neuroinflammation via sustaining mitochondrial function. In the current study, experiments were performed to understand the beneficial effects of mitochonic acid 5 (MA-5) on tumor necrosis factor-α (TNF-α)-mediated neuronal injury and mitochondrial damage. Our data illustrated that MA-5 pretreatment reduced inflammation response induced by TNF-α in CATH.a cells. Molecular investigations demonstrated that MA-5 pretreatment repressed oxidative stress, inhibited endoplasmic reticulum stress, sustained cellular energy metabolism, and blocked cell apoptosis induced by TNF-α stress. Further, we found that MA-5 treatment elevated the expression of Sirtuin 3 (Sirt3) and this effect was dependent on the activation of AMP-activated protein kinase (AMPK) pathway. Blockade of AMPK abolished the promotive action of MA-5 on Sirt3 and thus mediated mitochondrial damage and cell death. Besides, we also found that MA-5 treatment augmented Parkin-related mitophagy and increased mitophagy promoted CATH.a cells survival via improving mitochondrial function. Knockdown of Parkin abolished the beneficial action of MA-5 on mitochondrial homeostasis and CATH.a cell survival. Altogether, our results confirm that MA-5 is an effective drug to attenuate neuroinflammation via sustaining mitochondrial damage and promoting CATH.a cell survival. The protective action of MA-5 on neuronal damage is associated with Parkin-related mitophagy and the activation of AMPK-Sirt3 pathways.

Melatonin ameliorates endoplasmic reticulum stress in N2a neuroblastoma cell hypoxia-reoxygenation injury by activating the AMPK-Pak2 pathway

Endoplasmic reticulum (ER) stress has been identified as a primary factor involved in brain ischemia-reperfusion injury progression. p21-activated kinase 2 (Pak2) is a novel ER function regulator. The aim of our study is to explore the influence of Pak2 on ER stress and determine whether melatonin attenuates ER stress-mediated cell death by modulating Pak2 expression in vitro using N2a cells. The results of our study demonstrated that hypoxia-reoxygenation (HR) injury repressed the levels of Pak2, an effect that was accompanied by activation of ER stress. In addition, decreased Pak2 was associated with oxidative stress, calcium overload, and caspase-12-mediated apoptosis activation in HR-treated N2a cells. Interestingly, melatonin treatment reversed the decreased Pak2 expression under HR stress. Knockdown of Pak2 abolished the protective effects of melatonin on ER stress, oxidative stress, and caspase-12-related N2a cells death. Additionally, we found that Pak2 was regulated by melatonin via the AMPK pathway; inhibition of AMPK prevented melatonin-mediated Pak2 upregulation, a result that was accompanied by an increase in N2a cell death. Altogether, these results identify the AMPK-Pak2 axis as a new signaling pathway responsible for ER stress and N2a cell viability under HR injury. Modulation of the AMPK-Pak2 cascade via supplementation of melatonin might be considered an effective approach to attenuate reperfusion-mediated N2a cell damage via repression of ER stress.

Large tumor suppressor kinase 2 overexpression attenuates 5-FU-resistance in colorectal cancer via activating the JNK-MIEF1-mitochondrial division pathway

Background

5-Fluorouracil (5-FU) is a standard treatment for colorectal cancer, but most patients develop 5-FU resistance. Here, we conducted experiments to identify an effective approach to augment 5-FU-based treatment in colorectal cancer in vitro.

Methods

SW480 cells were in the present study and treated with 5-FU. Besides, LATS2 adenovirus vectors were infected into SW480 cells. Western blotting, immunofluorescence and ELISA were used to evaluate cell death and mitochondrial function. Pathway blocker was used to verify the role of MAPK-JNK pathway in SW480 cell death.

Results

An obvious drop in large tumor suppressor kinase 2 (LATS2) expression was observed in SW480 cells after treatment with 5-FU. In addition, upregulation of LATS2 expression through infection with LATS2 adenovirus further increased the reduction of SW480 cell viability induced by 5-FU. Functional exploration showed that 5-FU treatment suppressed mitochondrial membrane potential, enhanced cyt-c release into the nucleus, induced an oxidative injury environment by promoting ROS production, and eventually upregulated Bax-related mitochondrial apoptosis. Besides, LATS2 overexpression in combination with 5-FU treatment further perturbed mitochondrial homeostasis, and this effect was achieved by elevating mitochondrial division. Mechanistically, LATS2 overexpression and 5-FU co-treatment amplified mitochondrial division by upregulating MIEF1 expression in a manner dependent on MAPK-JNK axis. Knockdown of MIEF1 using an siRNA-mediated loss of function assay and/or inhibition of the MAPK-JNK pathway using the specific inhibitor SP600125 abolished LATS2/5-FU-mediated deleterious effects on mitochondrial performance and SW480 cell viability.

Conclusions

In light of the above findings, LATS2 downregulation could be a potential mechanism of low response to 5-FU treatment. Overexpression of LATS2 to further disrupt mitochondrial function via the JNK-MIEF1 signalling pathway might be a method to optimize 5-FU-based chemotherapy.

Overexpression of macrophage stimulating 1 enhances the anti-tumor effects of IL-24 in esophageal cancer via inhibiting ERK-Mfn2 signaling-dependent mitophagy

Although cytokine-based therapy is a promising tool to control the progression of esophageal cancer, low therapeutic responses largely compromise treatment efficacy through unidentified mechanisms. The goal of our study was to explore the roles of macrophage stimulating 1 (Mst1) and mitophagy in enhancing IL-24-based cytokine therapy in esophageal cancer. Our data demonstrated that IL-24 application promoted cancer death by inducing mitochondrial stress, as manifested by mitochondrial ROS overproduction, mitochondrial potential dissipation, cellular ATP deprivation and mitochondrial death activation. Overexpression of Mst1 enhanced IL-24-mediated mitochondrial damage and further augmented IL-24-induced death in esophageal cancer. Molecular investigations illustrated that the IL-24-activated mitochondrial response is accompanied by activation of mitophagy, a protective mechanism to attenuate mitochondrial damage. However, Mst1 overexpression inhibited mitophagy activity, which was achieved by inactivating the ERK-Mfn2 signaling pathway. The re-activation of mitophagy abolished the cancer-killing effects of Mst1 overexpression on esophageal cancer. Altogether, our data demonstrate that IL-24-related therapeutic resistance is associated with mitophagy activation. Mst1 overexpression inhibits mitophagy activity via suppressing the ERK-Mfn2 pathway, ultimately augmenting IL-24-inducd esophageal cancer death via enhanced mitochondrial stress.

Anti-tumor effect of LATS2 on liver cancer death: Role of DRP1-mediated mitochondrial division and the Wnt/β-catenin pathway

Large tumor suppressor 2 (LATS2), an important mediator of the cell apoptotic response pathway, has been linked to the progression of several cancers. Here, we described the molecular feature of LATS2 as a novel antitumor factor in liver cancer cells in vitro. Western blotting was used to detect the expression of LATS2 and its downstream factors. ELISA, immunofluorescence, and flow cytometry were used to evaluate the alterations of mitochondrial function in response to LATS2 overexpression. Adenovirus-loaded LATS2 and siRNA against DRP1 were transfected into liver cancer cells to overexpress LATS2 and knockdown DRP1 expression, respectively. The results of the present study demonstrated that overexpression of LATS2 was closely associated with more liver cancer cell death. Mechanistically, LATS2 overexpression increased the expression of DRP1, and DRP1 elevated mitochondrial division, an effect that was accompanied by mitochondrial dysfunction, including mitochondrial membrane potential reduction, mitochondrial respiratory complex downregulation, mitochondrial cyt-c release into the nucleus and mitochondrial oxidative injury. Moreover, LATS2 overexpression also initiated mitochondrial apoptosis, and this process was highly dependent on DRP1-related mitochondrial division. Molecular investigations demonstrated that LATS2 modulated DRP1 expression via the Wnt/β-catenin pathway. Inhibition of the Wnt/β-catenin pathway pregented LATS2-mediated DRP1 upregulation, ultimately sustaining mitochondrial function and cell viability in the presence of LATS2 overexpression. Altogether, the above data identify LATS2-Wnt/β-catenin/DRP1/mitochondrial division as a novel anticancer signaling pathway promoting cancer cell death, which might be an attractive therapeutic target for the treatment of hepatocellular carcinoma.

Allogenic endothelial progenitor cell transplantation increases flap survival through an upregulation of eNOs and VEGF on venous flap survival in rabbits

BACKGROUND

Endothelial progenitor cells (EPCs) are one type of bone marrow hematopoietic stromal cells which play a vital role in neovascularization and tissue repair. In this study, we investigated whether EPCs promote flap survival in a rabbit venous model.

MATERIALS AND METHODS

EPCs were customized from CHI Scientific, Inc, China. Thirty-six rabbits were randomly assigned to either the sham group (n = 12), the control group (n = 12) or the EPC transplantation group (n = 12). A 10 × 6 cm venous flap was created on the rabbit abdomen. Both the EPC transplantation and control groups had the same volume of EPCs-PBS (phosphate buffered saline) and PBS on postoperative day 1. Flap survival, blood flow, histopathology, expression of endothelial nitric oxide synthase (eNOs) and Vascular Endothelial Growth Factor (VEGF) were detected on postoperative day 10.

RESULTS

Cellular immunofluorescence assay positively confirmed that the EPCs were undergoing differentiation. The survival rate of the flap in the EPC transplantation group was 58.4 ± 7.1%, which was significantly higher than that of the control group (4.8 ± 3.4%) (p<0.01). Histological examination revealed that the EPC transplantation group had higher microvessel density, fewer inflammatory cells, and a higher expression of eNOs and VEGF. Significantly increased blood flow perfusion was seen in the EPC transplantation group using laser Doppler imaging. The Western Blot technique revealed that the expression of eNOs and VEGF in the EPC transplantation group were both significantly higher than those in the control group.

CONCLUSION

This study demonstrated that EPC transplantation improved venous flap survival in rabbits. The present findings may provide insight into the promotion of venous flap survival in clinical practice in the future.