Negative pressure wound therapy improves bone regeneration by promoting osteogenic differentiation via the AMPK-ULK1-autophagy axis

NRSN2 promotes the malignant behavior of HPV-transfected laryngeal carcinoma cells through AMPK/ULK1 pathway mediated autophagy activation

Neurensin-2 (NRSN2) performs a pro-carcinogenic function in multiple cancers. However, the function of NRSN2 in HPV-infected laryngeal carcinoma (LC) remains unclear. HPV transfection was performed in LC cells. The mRNA and protein levels were monitored using RT-qPCR, immunoblotting, and IF. Cell viability and proliferation were found using the CCK-8 assay and Edu staining. Cell invasion, migration, and apoptosis were probed using the Transwell, wound healing, and flow cytometry, respectively. The autophagosome was observed using TEM. NRSN2 was overexpressed in HPV-transfected LC cells. Inhibition of NRSN2 restrained the autophagy and malignant behavior of HPV-transfected LC cells. Meanwhile, the inhibition of AMPK/ULK1 pathway limited the increased autophagy of HPV-transfected LC cells caused by NRSN2 overexpression. Furthermore, NRSN2 knockdown inhibits autophagy by suppressing AMPK/ULK1 pathway, thereby restraining the malignant behavior of HPV-transfected LC cells. Our research confirmed that HPV transfection increased the autophagy and malignant behavior of LC cells by regulating the NRSN2-mediated activation of the AMPK/ULK1 pathway, offering a new target for cure of LC.

SNHG1 knockdown promotes osteogenic differentiation of hDFSCs through anti-oxidative stress mediated by autophagy

The long noncoding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) plays a crucial role in tumorigenesis and is frequently employed as a prognostic biomarker. However, its involvement in the osteogenic differentiation of oral stem cells, particularly human dental follicle stem cells (hDFSCs), remains unclear. Our investigation revealed that the absence of SNHG1 enhances the osteogenic differentiation of hDFSCs. Furthermore, the downregulation of SNHG1 induces autophagy in hDFSCs, leading to a reduction in intracellular oxidative stress levels. Notably, this effect is orchestrated through the epigenetic regulation of EZH2. Our study unveils a novel function of SNHG1 in governing the osteogenic differentiation of hDFSCs, offering fresh insights for an in-depth exploration of the molecular mechanisms underlying dental follicle development. These findings not only provide a foundation for advancing the understanding of SNHG1 but also present innovative perspectives for promoting the repair and regeneration of periodontal supporting tissue, ultimately contributing to the restoration of periodontal health and tooth function.

Regulation of mesenchymal stem cell differentiation by autophagy

Autophagy, a process that isolates intracellular components and fuses them with lysosomes for degradation, plays an important cytoprotective role by eliminating harmful intracellular substances and maintaining cellular homeostasis. Mesenchymal stem cells (MSCs) are multipotent progenitor cells with the capacity for self-renewal that can give rise to a subset of tissues and therefore have potential in regenerative medicine. However, a variety of variables influence the biological activity of MSCs following their proliferation and transplantation in vitro. The regulation of autophagy in MSCs represents a possible mechanism that influences MSC differentiation properties under the right microenvironment, affecting their regenerative and therapeutic potential. However, a deeper understanding of exactly how autophagy is mobilized to function as well as clarifying the mechanisms by which autophagy promotes MSCs differentiation is still needed. Here, we review the current literature on the complex link between MSCs differentiation and autophagy induced by various extracellular or intracellular stimuli and the molecular targets that influence MSCs lineage determination, which may highlight the potential regulation of autophagy on MSCs' therapeutic capacity, and provide a broader perspective on the clinical application of MSCs in the treatment of a wide range of diseases.

Ligustilide inhibits Purkinje cell ferritinophagy via the ULK1/NCOA4 pathway to attenuate valproic acid-induced autistic features

BACKGROUND

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder in which social impairment is the core symptom. Presently, there are no definitive medications to cure core symptoms of ASD, and most therapeutic strategies ameliorate ASD symptoms. Treatments with proven efficacy in autism are imminent. Ligustilide (LIG), an herbal monomer extracted from Angelica Sinensis and Chuanxiong, is mainly distributed in the cerebellum and widely used in treating neurological disorders. However, there are no studies on its effect on autistic-like phenotypes and its mechanism of action.

PURPOSE

Investigate the efficacy and mechanism of LIG in treating ASD using two Valproic acid(VPA)-exposed and BTBR T + Itpr3tf/J (BTBR) mouse models of autism.

METHODS

VPA-exposed mice and BTBR mice were given LIG for treatment, and its effect on autistic-like phenotype was detected by behavioral experiments, which included a three-chamber social test. Subsequently, RNA-Sequence(RNA-Seq) of the cerebellum was performed to observe the biological changes to search target pathways. The autophagy and ferroptosis pathways screened were verified by WB(Western Blot) assay, and the cerebellum was stained by immunofluorescence and examined by electron microscopy. To further explore the therapeutic mechanism, ULK1 agonist BL-918 was used to block the therapeutic effect of LIG to verify its target effect.

RESULTS

Our work demonstrates that LIG administration from P12-P14 improved autism-related behaviors and motor dysfunction in VPA-exposed mice. Similarly, BTBR mice showed the same improvement. RNA-Seq data identified ULK1 as the target of LIG in regulating ferritinophagy in the cerebellum of VPA-exposed mice, as evidenced by activated autophagy, increased ferritin degradation, iron overload, and lipid peroxidation. We found that VPA exposure-induced ferritinophagy occurred in the Purkinje cells, with enhanced NCOA4 and Lc3B expressions. Notably, the therapeutic effect of LIG disappeared when ULK1 was activated.

CONCLUSION

LIG treatment inhibits ferritinophagy in Purkinje cells via the ULK1/NCOA4-dependent pathway. Our study reveals for the first time that LIG treatment ameliorates autism symptoms in VPA-exposed mice by reducing aberrant Purkinje ferritinophagy. At the same time, our study complements the pathogenic mechanisms of autism and introduces new possibilities for its therapeutic options.

Optimal time to definitive enucleation of large cysts following marsupialization: a single center, retrospective study

OBJECTIVES

Optimal time to enucleation following marsupialization of large odontogenic mandibular cysts is undefined. We aim to assess volume reduction throughout follow-up, to indicate optimal time to enucleation. Secondary objectives include the identification of factors influencing cyst reduction.

STUDY DESIGN

We retrospectively enrolled 15 patients with mandibular cysts of different histological types treated with marsupialization at our center between 2018-2022. Cyst volume was assessed with cone-beam computed tomography (CBCT) and a semi-automatic segmentation algorithm, at baseline and between 6-8 months post marsupialization.

RESULTS

The overall mean cyst volume reduction percent (VR%) was 57.7% or 0.2% per day. VR% at 8 months was significantly higher than those assessed at 6-7 months (67.1% vs 47.1%, p=0.003). Time to CBCT was the only independent variable influencing cyst VR%.

CONCLUSION

Our study proves that the optimal time to enucleation for mandibular cyst is 8 months, independent of histological cyst type, patient age, baseline cyst volume and the number of pre-operative residual bone walls.

Role of Autophagy and Pyroptosis in Intervertebral Disc Degeneration

Intervertebral disc degeneration is a chronic degenerative disease caused by the interaction of genetic and environmental factors, mainly manifested as lower back pain. At present, the diagnosis of intervertebral disc degeneration mainly relies on imaging. However, early intervertebral disc degeneration is usually insidious, and there is currently a lack of relevant clinical biomarkers that can reliably reflect early disease progression. Pyroptosis is a regulatory form of cell death triggered by the activation of inflammatory bodies and caspase, which can induce the formation of plasma membrane pores and cell swelling or lysis. Previous studies have shown that during the progression of intervertebral disc degeneration, sustained activation of inflammasomes leads to nuclear cell pyroptosis, which can occur in the early stages of intervertebral disc degeneration. Moreover, intervertebral disc nucleus pulposus cells adapt to the external environment through autophagy and maintain cellular homeostasis and studying the mechanism of autophagy in IDD and intervening in its pathological and physiological processes can provide new ideas for the clinical treatment of IDD. This review analyzes the effects of pyroptosis and autophagy on IDD by reviewing relevant literature in recent years, in order to explore the relationship between pyroptosis, autophagy and IDD.

Simplified and modified Limberg flap plus vacuum-assisted closure for treatment of sacrococcygeal pilonidal sinus disease

BACKGROUND

Pilonidal sinus disease (PSD), a chronic inflammatory disease, affects the sacrococcygeal soft tissue, especially in young adults. The ideal treatment for PSD remains divergence. This study evaluated the application of a simplified modified Limberg flap combined with vacuum-assisted closure for treating PSD.

METHODS

This prospective study was conducted from 1 June 2017 to 31 March 2022 in Changhai Hospital, Naval Military Medical University, Shanghai, China. The study included 88 male patients (91.7%) and 8 female patients (8.3%). The 96 patients ranged in age from 15 to 34 years (mean ± SD, 23 ± 4.4). Under general anaesthesia, all patients underwent simplified modified Limberg flap reconstruction with vacuum-assisted closure. The patient's weight, surgical time, extubation time, hospital stay, time to return to normal life or work, wound infection, wound dehiscence and recurrence rate were recorded. The visual analogue scale (VAS) score and the Vancouver scar score were used to score patients' pain and scars in the surgical area.

RESULTS

The volume of resected diseased tissue was 13.5-120 (mean ± SD, 34.993 ± 24.406) cm2 . The average surgical time during the treatment period was 97.68 ± 18.72 min, and the average extubation time was (6.36 ± 1.55) days, the mean hospital stay was 19.4 days; no patients were lost to follow-up. None of the patients experienced post-operative recurrence, wound infection, seroma or hematoma. Six patients (6.3%) experienced wound dehiscence at the flap tip around the natal cleft. The mean time to the resumption of daily activities was 26.3 days. The average VAS pain score was (6.00 ± 1.53) points, and the average Vancouver scar score was (5.96 ± 1.51) points, 12 patients (12.5%) were dissatisfied with their aesthetic results, and the average beauty satisfaction score is (6.64 ± 1.28) points.

CONCLUSIONS

Simplified modified Limberg flap reconstruction with vacuum-assisted closure surgery is an effective and innovative method for the treatment of PSD, with a low recurrence rate and rapid recovery.

COPI Vesicle Disruption Inhibits Mineralization via mTORC1-Mediated Autophagy

Bone mineralization is a sophisticated regulated process composed of crystalline calcium phosphate and collagen fibril. Autophagy, an evolutionarily conserved degradation system, whereby double-membrane vesicles deliver intracellular macromolecules and organelles to lysosomes for degradation, has recently been shown to play an essential role in mineralization. However, the formation of autophagosomes in mineralization remains to be determined. Here, we show that Coat Protein Complex I (COPI), responsible for Golgi-to-ER transport, plays a pivotal role in autophagosome formation in mineralization. COPI vesicles were increased after osteoinduction, and COPI vesicle disruption impaired osteogenesis. Mechanistically, COPI regulates autophagy activity via the mTOR complex 1 (mTORC1) pathway, a key regulator of autophagy. Inhibition of mTOR1 rescues the impaired osteogenesis by activating autophagy. Collectively, our study highlights the functional importance of COPI in mineralization and identifies COPI as a potential therapeutic target for treating bone-related diseases.

In vitro and in vivo killing effects of methionine enkephalin on osteosarcoma

OBJECTIVE

This study aimed to investigate the underlying regulatory effects of methionine enkephalin (MENK) on osteosarcoma.

METHODS

The Cell Counting Kit-8 assay, clone formation, wound healing, transwell assay, and flow cytometry were performed to measure the effects of MENK on the proliferation, migration, invasion, and apoptosis of MG-63 and Saos-2 cells. Opiate growth factor receptor expression (OGFr) in cells was stably knocked down using siRNA. A tumor model was established by inoculating MG-63 cells into mice. Flow cytometry was performed to identify alterations in mice bone marrow, spleen, and tumor tissue immune cells. The phenotype of tumor-associated macrophages was determined using immunohistochemistry. After OGFr knockdown or/and treatment with MENK, Bax, Bcl-2, caspase 3, caspase 9, and PARP expression levels were characterized using qRT-PCR, western blot, and WES, respectively.

RESULTS

MENK could significantly inhibit the proliferation, invasion, and migration of MG-63 and Saos-2, arrest the cell cycle in the G0/G1 phase, upregulate Bax, caspase 3, caspase 9, and PARP expression, and downregulate Bcl-2 expression. Tumor size and weight were lower in the MENK group than those in the control group. MENK-treated mice exhibited a reduced ratio of CD11b + Gr-1 + myeloid-derived suppressor cells. MENK increased the ratio of M1-type macrophages and decreased the proportion of M2-type macrophages in tumor tissue. Furthermore, the level of TNF-α significantly increased while that of IL-10 decreased in MENK-treated mice. The effect of MENK could be partly reversed by OGFr knockdown.

CONCLUSION

MENK reduces the abundance of myeloid-derived suppressor cells, induces M1 polarization of macrophages, and exhibits an inhibitory effect on osteosarcoma.

Beneficial effects of Apelin-13 on metabolic diseases and exercise

Apelin, a novel endogenous ligand of the G-protein-coupled receptor APJ, is encoded by the APLN gene and can be hydrolyzed into multiple subtypes, with Apelin-13 being one of the most active subtypes of the Apelin family. Recent studies have revealed that Apelin-13 functions as an adipokine that participates in the regulation of different biological processes, such as oxidative stress, inflammation, apoptosis, and energy metabolism, thereby playing an important role in the prevention and treatment of various metabolic diseases. However, the results of recent studies on the association between Apelin-13 and various metabolic states remain controversial. Furthermore, Apelin-13 is regulated or influenced by various forms of exercise and could therefore be categorized as a new type of exercise-sensitive factor that attenuates metabolic diseases. Thus, in this review, our purpose was to focus on the relationship between Apelin-13 and related metabolic diseases and the regulation of response movements, with particular reference to the establishment of a theoretical basis for improving and treating metabolic diseases.

The Effect of the Hip Flexion Angle in Osteonecrosis of the Femoral Head Based on China-Japan Friendship Hospital Classification - A Finite Element Study

OBJECTIVE

The alteration in the mechanical environment of the necrotic area is the primary cause of the collapse observed in osteonecrosis of the femoral head (ONFH). This study aims to evaluate the biomechanical implications of the China-Japan Friendship Hospital (CJFH) classification system and hip flexion angles on the necrotic area in ONFH using finite element analysis (FEA). The goal is to provide valuable guidance for hip preservation treatments and serve as a reference for clinical diagnosis and therapeutic interventions.

METHODS

Hip tomography CT scan data from a healthy volunteer was used to create a 3D model of the left hip. The model was preprocessed and imported into Solidworks 2018, based on the CJFH classification. Material parameters and boundary conditions were applied to each fractal model in ANSYS 21.0. Von Mises stresses were calculated, and maximum deformation values were obtained to evaluate the biomechanical effects of the load on the necrotic area and post-necrotic femur, as well as assess each fractal model's collapse risk.

RESULTS

(1) At the same hip flexion angle, maximum deformation followed this order: M Type < C Type < L Type. The L3 type necrotic area experienced the most significant deformation at 0, 60, and 110° angles (1.121, 1.7913, and 1.8239 mm respectively). (2) Under the same CJFH classification, maximum deformation values increased with hip flexion angle (0 < 60 < 110°), suggesting a higher risk of collapse at larger angles. (3) Von Mises stress results showed that the maximum stress was not located in the necrotic area but near the inner and outer edge of the femoral neck, indicating decreased stiffness and strength of the subchondral bone after osteonecrosis.

CONCLUSION

The study found that femoral head collapse risk was higher when the necrotic area was located in the lateral column under the same stress load and flexion angle. Mechanical properties of the necrotic area changed, resulting in decreased bone strength and stiffness. Large-angle hip flexion is more likely to cause excessive deformation of the necrotic area; thus, ONFH patients should reduce or avoid large-angle hip flexion during weight-bearing training in rehabilitation activities.

The tumour-promoting role of protein homeostasis: Implications for cancer immunotherapy

Protein homeostasis, an important aspect of cellular fitness that encompasses the balance of production, folding and degradation of proteins, has been linked to several diseases of the human body. Multiple interconnected pathways coordinate to maintain protein homeostasis within the cell. Recently, the role of the protein homeostasis network in tumorigenesis and tumour progression has gradually come to light. Here, we summarize the involvement of the most prominent components of the protein quality control mechanisms (HSR, UPS, autophagy, UPR and ERAD) in tumour development and cancer immunity. In addition, evidence for protein quality control mechanisms and targeted drugs is outlined, and attempts to combine these drugs with cancer immunotherapy are discussed. Altogether, combination therapy represents a promising direction for future investigations, and this exciting insight will be further illuminated by the development of drugs that can reach a balance between the benefits and hazards associated with protein homeostasis interference.

Activating Wnt/β-catenin signaling by autophagic degradation of APC contributes to the osteoblast differentiation effect of soy isoflavone on osteoporotic mesenchymal stem cells

The functional role of autophagy in regulating differentiation of bone marrow mesenchymal stem cells (MSCs) has been studied extensively, but the underlying mechanism remains largely unknown. The Wnt/β-catenin signaling pathway plays a pivotal role in the initiation of osteoblast differentiation of mesenchymal progenitor cells, and the stability of core protein β-catenin is tightly controlled by the APC/Axin/GSK-3β/Ck1α complex. Here we showed that genistein, a predominant soy isoflavone, stimulated osteoblast differentiation of MSCs in vivo and in vitro. Female rats were subjected to bilateral ovariectomy (OVX); four weeks after surgery the rats were orally administered genistein (50 mg·kg-1·d-1) for 8 weeks. The results showed that genistein administration significantly suppressed the bone loss and bone-fat imbalance, and stimulated bone formation in OVX rats. In vitro, genistein (10 nM) markedly activated autophagy and Wnt/β-catenin signaling pathway, and stimulated osteoblast differentiation in OVX-MSCs. Furthermore, we found that genistein promoted autophagic degradation of adenomatous polyposis coli (APC), thus initiated β-catenin-driven osteoblast differentiation. Notably, genistein activated autophagy through transcription factor EB (TFEB) rather than mammalian target of rapamycin (mTOR). These findings unveil the mechanism of how autophagy regulates osteogenesis in OVX-MSCs, which expands our understanding that such interplay could be employed as a useful therapeutic strategy for treating postmenopausal osteoporosis.

iPSCs ameliorate hypoxia-induced autophagy and atrophy in C2C12 myotubes via the AMPK/ULK1 pathway

BACKGROUND

Duchenne muscular dystrophy (DMD) is an X-linked lethal genetic disorder for which there is no effective treatment. Previous studies have shown that stem cell transplantation into mdx mice can promote muscle regeneration and improve muscle function, however, the specific molecular mechanisms remain unclear. DMD suffers varying degrees of hypoxic damage during disease progression. This study aimed to investigate whether induced pluripotent stem cells (iPSCs) have protective effects against hypoxia-induced skeletal muscle injury.

RESULTS

In this study, we co-cultured iPSCs with C2C12 myoblasts using a Transwell nested system and placed them in a DG250 anaerobic workstation for oxygen deprivation for 24 h. We found that iPSCs reduced the levels of lactate dehydrogenase and reactive oxygen species and downregulated the mRNA and protein levels of BAX/BCL2 and LC3II/LC3I in hypoxia-induced C2C12 myoblasts. Meanwhile, iPSCs decreased the mRNA and protein levels of atrogin-1 and MuRF-1 and increased myotube width. Furthermore, iPSCs downregulated the phosphorylation of AMPKα and ULK1 in C2C12 myotubes exposed to hypoxic damage.

CONCLUSIONS

Our study showed that iPSCs enhanced the resistance of C2C12 myoblasts to hypoxia and inhibited apoptosis and autophagy in the presence of oxidative stress. Further, iPSCs improved hypoxia-induced autophagy and atrophy of C2C12 myotubes through the AMPK/ULK1 pathway. This study may provide a new theoretical basis for the treatment of muscular dystrophy in stem cells.

Sulforaphane prevents LPS-induced inflammation by regulating the Nrf2-mediated autophagy pathway in goat mammary epithelial cells and a mouse model of mastitis

BACKGROUND

Mastitis not only deteriorates the composition or quality of milk, but also damages the health and productivity of dairy goats. Sulforaphane (SFN) is a phytochemical isothiocyanate compound with various pharmacological effects such as anti-oxidant and anti-inflammatory. However, the effect of SFN on mastitis has yet to be elucidated. This study aimed to explore the anti-oxidant and anti-inflammatory effects and potential molecular mechanisms of SFN in lipopolysaccharide (LPS)-induced primary goat mammary epithelial cells (GMECs) and a mouse model of mastitis.

RESULTS

In vitro, SFN downregulated the mRNA expression of inflammatory factors (tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6), inhibited the protein expression of inflammatory mediators (cyclooxygenase-2 (COX2), and inducible nitric oxide synthase (iNOS)) while suppressing nuclear factor kappa-B (NF-κB) activation in LPS-induced GMECs. Additionally, SFN exhibited an antioxidant effect by increasing Nrf2 expression and nuclear translocation, up-regulating antioxidant enzymes expression, and decreasing LPS-induced reactive oxygen species (ROS) production in GMECs. Furthermore, SFN pretreatment promoted the autophagy pathway, which was dependent on the increased Nrf2 level, and contributed significantly to the improved LPS-induced oxidative stress and inflammatory response. In vivo, SFN effectively alleviated histopathological lesions, suppressed the expression of inflammatory factors, enhanced immunohistochemistry staining of Nrf2, and amplified of LC3 puncta LPS-induced mastitis in mice. Mechanically, the in vitro and in vivo study showed that the anti-inflammatory and anti-oxidative stress effects of SFN were mediated by the Nrf2-mediated autophagy pathway in GMECs and a mouse model of mastitis.

CONCLUSIONS

These results indicate that the natural compound SFN has a preventive effect on LPS-induced inflammation through by regulating the Nrf2-mediated autophagy pathway in primary goat mammary epithelial cells and a mouse model of mastitis, which may improve prevention strategies for mastitis in dairy goats.

A Case of Fibula Regeneration after Below-the-knee Amputation in an Adult

We report the case of an adult with fibula regeneration after below-the-knee amputation. Fibula regeneration conventionally occurs at the donor site of children after autogenous fibula transplantation when the periosteum is preserved. However, the patient was an adult, and the regenerated fibula was 7-cm long and grew directly from the stump. A 47-year-old man was referred to the plastic surgery department owing to stump pain. He had an open comminuted fracture of the right fibula and tibia due to a traffic accident when he was 44 years old and underwent below-the-knee amputation and negative pressure wound therapy for skin defects. The patient recovered and was able to walk using a prosthetic limb. Upon radiography, the fibula was found to have regenerated 7 cm directly from the stump. Pathological examination revealed that the regenerated fibula contained normal bone tissue and neurovascular bundles in the cortex. The periosteum, mechanical stimuli with limb proteases, and negative pressure wound therapy were suspected to have accelerated bone regeneration. He had no inhibitory factors for bone regeneration, including diabetes mellitus, peripheral arterial disease, or active smoking status. After the resection of the regenerated fibula, the patient was ambulatory without further bone regeneration or pain. This case report suggests that bone regeneration may occur even in adults. The surgeon should not leave any part of the periosteum behind in patients undergoing amputation. In adult amputees complaining of stump pain, the possibility of bone regeneration may be considered.

The role of integrin family in bone metabolism and tumor bone metastasis

Integrins have been the research focus of cell-extracellular matrix adhesion (ECM) and cytokine receptor signal transduction. They are involved in the regulation of bone metabolism of bone precursor cells, mesenchymal stem cells (MSCs), osteoblasts (OBs), osteoclasts (OCs), and osteocytes. Recent studies expanded and updated the role of integrin in bone metabolism, and a large number of novel cytokines were found to activate bone metabolism pathways through interaction with integrin receptors. Integrins act as transducers that mediate the regulation of bone-related cells by mechanical stress, fluid shear stress (FSS), microgravity, hypergravity, extracellular pressure, and a variety of physical factors. Integrins mediate bone metastasis of breast, prostate, and lung cancer by promoting cancer cell adhesion, migration, and survival. Integrin-mediated targeted therapy showed promising prospects in bone metabolic diseases. This review emphasizes the latest research results of integrins in bone metabolism and bone metastasis and provides a vision for treatment strategies.

The emerging mechanisms and functions of microautophagy

'Autophagy' refers to an evolutionarily conserved process through which cellular contents, such as damaged organelles and protein aggregates, are delivered to lysosomes for degradation. Different forms of autophagy have been described on the basis of the nature of the cargoes and the means used to deliver them to lysosomes. At present, the prevailing categories of autophagy in mammalian cells are macroautophagy, microautophagy and chaperone-mediated autophagy. The molecular mechanisms and biological functions of macroautophagy and chaperone-mediated autophagy have been extensively studied, but microautophagy has received much less attention. In recent years, there has been a growth in research on microautophagy, first in yeast and then in mammalian cells. Here we review this form of autophagy, focusing on selective forms of microautophagy. We also discuss the upstream regulatory mechanisms, the crosstalk between macroautophagy and microautophagy, and the functional implications of microautophagy in diseases such as cancer and neurodegenerative disorders in humans. Future research into microautophagy will provide opportunities to develop novel interventional strategies for autophagy- and lysosome-related diseases.

Mesenchymal Stem Cells and Their Exocytotic Vesicles

Mesenchymal stem cells (MSCs), as a kind of pluripotent stem cells, have attracted much attention in orthopedic diseases, geriatric diseases, metabolic diseases, and sports functions due to their osteogenic potential, chondrogenic differentiation ability, and adipocyte differentiation. Anti-inflammation, anti-fibrosis, angiogenesis promotion, neurogenesis, immune regulation, and secreted growth factors, proteases, hormones, cytokines, and chemokines of MSCs have been widely studied in liver and kidney diseases, cardiovascular and cerebrovascular diseases. In recent years, many studies have shown that the extracellular vesicles of MSCs have similar functions to MSCs transplantation in all the above aspects. Here we review the research progress of MSCs and their exocrine vesicles in recent years.

Negative-Pressure Wound Therapy: What We Know and What We Need to Know

Negative-pressure wound therapy (NPWT) promotes wound healing by applying negative pressure to the wound surface. A quarter of a century after its introduction, NPWT has been used in various clinical conditions, although molecular biological evidence is insufficient due to delay in basic research. Here, we have summarized the history of NPWT, its mechanism of action, what is currently known about it, and what is expected to be known in the future. Particularly, attention has shifted from the four main mechanisms of NPWT to the accompanying secondary effects, such as effects on various cells, bacteria, and surgical wounds. This chapter will help the reader to understand the current status and shortcomings of NPWT-related research, which could aid in the development of basic research and, eventually, clinical use with stronger scientific evidence.

Combined computational analysis and cytology show limited depth osteogenic effect on bone defects in negative pressure wound therapy

Background: The treatment of bone defects remains a clinical challenge. The effect of negative pressure wound therapy (NPWT) on osteogenesis in bone defects has been recognized; however, bone marrow fluid dynamics under negative pressure (NP) remain unknown. In this study, we aimed to examine the marrow fluid mechanics within trabeculae by computational fluid dynamics (CFD), and to verify osteogenic gene expression, osteogenic differentiation to investigate the osteogenic depth under NP. Methods: The human femoral head is scanned using micro-CT to segment the volume of interest (VOI) trabeculae. The VOI trabeculae CFD model simulating the bone marrow cavity is developed by combining the Hypermesh and ANSYS software. The effect of trabecular anisotropy is investigated, and bone regeneration effects are simulated under NP scales of -80, -120, -160, and -200 mmHg. The working distance (WD) is proposed to describe the suction depth of the NP. Finally, gene sequence analysis, cytological experiments including bone mesenchymal stem cells (BMSCs) proliferation and osteogenic differentiation are conducted after the BMSCs are cultured under the same NP scale. Results: The pressure, shear stress on trabeculae, and marrow fluid velocity decrease exponentially with an increase in WD. The hydromechanics of fluid at any WD inside the marrow cavity can be theoretically quantified. The NP scale significantly affects the fluid properties, especially those fluid close to the NP source; however, the effect of the NP scale become marginal as WD deepens. Anisotropy of trabecular structure coupled with the anisotropic hydrodynamic behavior of bone marrow; An NP of -120 mmHg demonstrates the majority of bone formation-related genes, as well as the most effective proliferation and osteogenic differentiation of BMSCs compared to the other NP scales. Conclusion: An NP of -120 mmHg may have the optimal activated ability to promote osteogenesis, but the effective WD may be limited to a certain depth. These findings help improve the understanding of fluid mechanisms behind NPWT in treating bone defects.

Autophagy Balances Neuroinflammation in Alzheimer's Disease

Autophagy is a highly evolutionary conserved process that degrades cytosolic macromolecules or damaged organelles (e.g., mitochondria), as well as intracellular pathogens for energy and survival. Dysfunction of autophagy has been associated with the pathologies of Alzheimer's disease (AD), including Aβ plaques and neurofibrillary tangles. Recently, the presence of sustained immune response in the brain has been considered a new core pathology in AD. Accumulating evidence suggests that autophagy activation may suppress inflammation response through degrading inflammasomes or pro-inflammatory cytokines and improving immune system function in both clinical trials and preclinical studies. This review provides an overview of updated information on autophagy and inflammation and their potential mediators in AD. In summary, we believe that understanding the relationship between autophagy and inflammation will provide insightful knowledge for future therapeutic implications in AD.

Function and regulation of ULK1: From physiology to pathology

The expression of ULK1, a core protein of autophagy, is closely related to autophagic activity. Numerous studies have shown that pathological abnormal expression of ULK1 is associated with various human diseases such as neurological disorders, infections, cardiovascular diseases, liver diseases and cancers. In addition, new advances in the regulation of ULK1 have been identified. Furthermore, targeting ULK1 as a therapeutic strategy for diseases is gaining attention as new corresponding activators or inhibitors are being developed. In this review, we describe the structure and regulation of ULK1 as well as the current targeted activators and inhibitors. Moreover, we highlight the pathological disorders of ULK1 expression and its critical role in human diseases.

ATG12 deficiency results in intracellular glutamine depletion, abrogation of tumor hypoxia and a favorable prognosis in cancer

Hypoxia is a common feature of solid tumors and is associated with increased tumor progression, resistance to therapy and increased metastasis. Hence, tumor hypoxia is a prognostic factor independent of treatment modality. To survive hypoxia, cells activate macroautophagy/autophagy. Paradoxically, in several cancer types, mutations or loss of essential autophagy genes have been reported that are associated with earlier onset of tumor growth. However, to our knowledge, the phenotypic and therapeutic consequences of autophagy deficiency have remained unexplored. In this study, we determined autophagy-defects in head and neck squamous cell carcinoma (HNSCC) and observed that expression of ATG12 (autophagy related 12) was lost in 25%-40% of HNSCC. In line, ATG12 loss is associated with absence of hypoxia, as determined by pimonidazole immunohistochemistry. Hence, ATG12 loss is associated with improved prognosis after therapy in two independent HNSCC cohorts and 7 additional cancer types. In vivo, ATG12 targeting resulted in decreased hypoxia tolerance, increased necrosis and sensitivity of the tumor to therapy, but in vitro ATG12-deficient cells displayed enhanced survival in nutrient-rich culture medium. Besides oxygen, delivery of glucose was hampered in hypoxic regions in vivo, which increases the reliance of cells on other carbon sources (e.g., L-glutamine). We observed decreased intracellular L-glutamine levels in ATG12-deficient cells during hypoxia and increased cell killing after L-glutamine depletion, indicating a central role for ATG12 in maintaining L-glutamine homeostasis. Our results demonstrate that ATG12^low tumors represent a phenotypically different subtype that, due to the lowered hypoxia tolerance, display a favorable outcome after therapy.

Abbreviations: ARCON:accelerated radiotherapy with carbogen and nicotinamide; ATG: autophagy related; BrdUrd: bromodeoxyuridine; CA9/CAIX: carbonic anhydrase 9; HIF1A/HIF1α: hypoxia inducible factor 1 subunit alpha; HNSCC: head and neck squamous cell carcinoma; HPV: human papilloma virus; HR: hazard ratio; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MEF: mouse embryonic fibroblast; mRNA: messenger ribonucleic acid; PCR: polymerase chain reaction; SLC2A1/GLUT1: solute carrier family 2 member 1; TCGA: the Cancer Genome Atlas; TME: tumor microenvironment; UTR: untranslated region; VEGF: vascular endothelial growth factor