A feasibility study to predict 3D dose delivery accuracy for IMRT using DenseNet with log files.

OBJECTIVE: This study aims to explore the feasibility of DenseNet in the establishment of a three-dimensional (3D) gamma prediction model of IMRT based on the actual parameters recorded in the log files during delivery. METHODS: A total of 55 IMRT plans (including 367 fields) were randomly selected. The gamma analysis was performed using gamma criteria of 3% /3 mm (Dose Difference/Distance to Agreement), 3% /2 mm, 2% /3 mm, and 2% /2 mm with a 10% dose threshold. In addition, the log files that recorded the gantry angle, monitor units (MU), multi-leaf collimator (MLC), and jaws position during delivery were collected. These log files were then converted to MU-weighted fluence maps as the input of DenseNet, gamma passing rates (GPRs) under four different gamma criteria as the output, and mean square errors (MSEs) as the loss function of this model. RESULTS: Under different gamma criteria, the accuracy of a 3D GPR prediction model decreased with the implementation of stricter gamma criteria. In the test set, the mean absolute error (MAE) of the prediction model under the gamma criteria of 3% /3 mm, 2% /3 mm, 3% /2 mm, and 2% /2 mm was 1.41, 1.44, 3.29, and 3.54, respectively; the root mean square error (RMSE) was 1.91, 1.85, 4.27, and 4.40, respectively; the Sr was 0.487, 0.554, 0.573, and 0.506, respectively. There was a correlation between predicted and measured GPRs (P <  0.01). Additionally, there was no significant difference in the accuracy between the validation set and the test set. The accuracy in the high GPR group was high, and the MAE in the high GPR group was smaller than that in the low GPR group under four different gamma criteria. CONCLUSIONS: In this study, a 3D GPR prediction model of patient-specific QA using DenseNet was established based on log files. As an auxiliary tool for 3D dose verification in IMRT, this model is expected to improve the accuracy and efficiency of dose validation.

Low-Cytotoxic Core-Sheath ZnO NWs@TiO2-xNy Triggered Piezo-photocatalytic Antibacterial Activity.

Sonophotodynamic antimicrobial therapy (SPDAT) is recognized as a highly efficient biomedical treatment option, known for its versatility and remarkable healing outcomes. Nevertheless, there is a scarcity of sonophotosensitizers that demonstrate both low cytotoxicity and exceptional antibacterial effectiveness in clinical applications. In this paper, a novel ZnO nanowires (NWs)@TiO2-xNy core-sheath composite was developed, which integrates the piezoelectric effect and heterojunction to build dual built-in electric fields. Remarkably, it showed superb antibacterial effectiveness (achieving 95% within 60 min against S. aureus and ∼100% within 40 min against E. coli, respectively) when exposed to visible light and ultrasound. Due to the continuous interference caused by light and ultrasound, the material's electrostatic equilibrium gets disrupted. The modification in electrical properties facilitates the composite's ability to attract bacterial cells through electrostatic forces. Moreover, Zn-O-Ti and Zn-N-Ti bonds formed at the interface of ZnO NWs@TiO2-xNy, further enhancing the dual internal electric fields to accelerate the excited carrier separation to generate more reactive oxygen species (ROS), and thereby boosting the antimicrobial performance. In addition, the TiO2 layer limited Zn2+ dissolution into solution, leading to good biocompatibility and low cytotoxicity. Lastly, we suggest a mechanistic model to offer practical direction for the future development of antibacterial agents that are both low in toxicity and high in efficacy. In comparison to the traditional photodynamic therapy systems, ZnO NWs@TiO2-xNy composites exhibit super piezo-photocatalytic antibacterial activity with low toxicity, which shows great potential for clinical application as an antibacterial nanomaterial.

circCDK13-loaded small extracellular vesicles accelerate healing in preclinical diabetic wound models.

Chronic wounds are a major complication in patients with diabetes. Here, we identify a therapeutic circRNA and load it into small extracellular vesicles (sEVs) to treat diabetic wounds in preclinical models. We show that circCDK13 can stimulate the proliferation and migration of human dermal fibroblasts and human epidermal keratinocytes by interacting with insulin-like growth factor 2 mRNA binding protein 3 in an N6-Methyladenosine-dependent manner to enhance CD44 and c-MYC expression. We engineered sEVs that overexpress circCDK13 and show that local subcutaneous injection into male db/db diabetic mouse wounds and wounds of streptozotocin-induced type I male diabetic rats could accelerate wound healing and skin appendage regeneration. Our study demonstrates that the delivery of circCDK13 in sEVs may present an option for diabetic wound treatment.

Predicting the error magnitude in patient-specific QA during radiotherapy based on ResNet.

BACKGROUND: The error magnitude is closely related to patient-specific dosimetry and plays an important role in evaluating the delivery of the radiotherapy plan in QA. No previous study has investigated the feasibility of deep learning to predict error magnitude. OBJECTIVE: The purpose of this study was to predict the error magnitude of different delivery error types in radiotherapy based on ResNet. METHODS: A total of 34 chest cancer plans (172 fields) of intensity-modulated radiation therapy (IMRT) from Eclipse were selected, of which 30 plans (151 fields) were used for model training and validation, and 4 plans including 21 fields were used for external testing. The collimator misalignment (COLL), monitor unit variation (MU), random multi-leaf collimator shift (MLCR), and systematic MLC shift (MLCS) were introduced. These dose distributions of portal dose predictions for the original plans were defined as the reference dose distribution (RDD), while those for the error-introduced plans were defined as the error-introduced dose distribution (EDD). Different inputs were used in the ResNet for predicting the error magnitude. RESULTS: In the test set, the accuracy of error type prediction based on the dose difference, gamma distribution, and RDD + EDD was 98.36%, 98.91%, and 100%, respectively; the root mean squared error (RMSE) was 1.45-1.54, 0.58-0.90, 0.32-0.36, and 0.15-0.24; the mean absolute error (MAE) was 1.06-1.18, 0.32-0.78, 0.25-0.27, and 0.11-0.18, respectively, for COLL, MU, MLCR and MLCS. CONCLUSIONS: In this study, error magnitude prediction models with dose difference, gamma distribution, and RDD + EDD are established based on ResNet. The accurate prediction of the error magnitude under different error types can provide reference for error analysis in patient-specific QA.

SlGolS2 influences the metabolism of chlorophyll, carotenoid, and ethylene in tomato fruits.

Galactinol synthase (GolS), which catalyzes the synthesis of galactinol, is the first critical enzyme in the biosynthesis of raffinose family oligosaccharides (RFOs) and contributes to plant growth and development, and resistance mechanisms. However, its role in fruit development remains largely unknown. In this study, we used CRISPR-Cas9 gene editing technology to create the slgols2 mutation showing uniformly green fruits without the dark green shoulder, and promoting fruit ripening. Further analysis revealed that the galactinol was undetected in slgols2 ovaries and fruits. Additionally, the mutant suppressed the accumulation of chlorophyll (Chl) and chloroplast development in tomato fruits. RNA sequencing analysis showed that genes related to chlorophyll accumulation and chloroplast development, such as SlPORB, SlGLK2, and SlCABs were downregulated in slgols2 fruits. Moreover, slgols2 lines prompted early color transformation and ethylene release by regulating the expression of genes such as SlPSY1, SlCRTISO, SlACS2, SlACS4, SlE4, SlE8, SlRIN, SlNOR and SlAP2a. Overall, our study provides evidence for the involvement of SlGolS2 in the pigment and ethylene metabolism of tomato fruits.

Analysis and Verification of Heat Dissipation Structures Embedded in Substrates in Power Chips Based on Square Frustums Thermal through Silicon Vias.

A novel heat dissipation structure composed of square frustums thermal through silicon via array and embedded in P-type (100) silicon substrate is proposed to improve the heat dissipation capacity of power chips while reducing process difficulty. Based on theoretical analysis, the heat transfer model and thermo-electric coupling reliability model of a power chip with the proposed heat dissipation structure are established. A comparative study of simulation indicates that the proposed heat dissipation structure, which can avoid problems such as softness, poor rigidity, fragility and easy fracture caused by thinning chips has better heat dissipation capability than thinning the substrate of power chips.

MiR-17-5p-engineered sEVs Encapsulated in GelMA Hydrogel Facilitated Diabetic Wound Healing by Targeting PTEN and p21.

Delayed wound healing is a major complication of diabetes, and is associated with impaired cellular functions. Current treatments are unsatisfactory. Based on the previous reports on microRNA expression in small extracellular vesicles (sEVs), miR-17-5p-engineered sEVs (sEVs17-OE) and encapsulated them in gelatin methacryloyl (GelMA) hydrogel for diabetic wounds treatment are fabricated. SEVs17-OE are successfully fabricated with a 16-fold increase in miR-17-5p expression. SEVs17-OE inhibited senescence and promoted the proliferation, migration, and tube formation of high glucose-induced human umbilical vein endothelial cells (HG-HUVECs). Additionally, sEVs17-OE also performs a promotive effect on high glucose-induced human dermal fibroblasts (HG-HDFs). Mechanism analysis showed the expressions of p21 and phosphatase and tensin homolog (PTEN), as the target genes of miR-17-5p, are downregulated significantly by sEVs17-OE. Accordingly, the downstream genes and pathways of p21 and PTEN, are activated. Next, sEVs17-OE are loaded in GelMA hydrogel to fabricate a novel bioactive wound dressing and to evaluate their effects on diabetic wound healing. Gel-sEVs17-OE effectively accelerated wound healing by promoting angiogenesis and collagen deposition. The cellular mechanism may be associated with local cell proliferation. Therefore, a novel bioactive wound dressing by loading sEVs17-OE in GelMA hydrogel, offering an option for chronic wound management is successfully fabricated.

Mechanism and Solution of Overcharge Effect in Lithium-Sulfur Batteries.

Increasing the sulfur cathode load is an important method for promoting the commercialization of lithium-sulfur batteries. However, there is a common problem of overcharging in high-loading experiments, which is rarely reported. In this work, it is believed that an insulating layer of S8 forms on the current collector surface, hindering electron exchange with polysulfides. Continuous external current input during layer formation can cause irreversible electrode changes and overcharging. The general solution is to provide nucleation centers with adsorption sites to promote the 3D growth of the insulated S8 , thus avoiding overcharging. In this work,  a solution is proposed by providing nucleation centers by gallium nitrate, by regulating the 3D growth of S8 away from the surface of the current collector to avoid overcharging and by improving battery performance.

MiR-141-3p-Functionalized Exosomes Loaded in Dissolvable Microneedle Arrays for Hypertrophic Scar Treatment.

Hypertrophic scar (HS) is a common fibroproliferative disease caused by abnormal wound healing after deep skin injury. However, the existing approaches have unsatisfactory therapeutic effects, which promote the exploration of newer and more effective strategies. MiRNA-modified functional exosomes delivered by dissolvable microneedle arrays (DMNAs) are expected to provide new hope for HS treatment. In this study, a miRNA, miR-141-3p, which is downregulated in skin scar tissues and in hypertrophic scar fibroblasts (HSFs), is identified. MiR-141-3p mimics inhibit the proliferation, migration, and myofibroblast transdifferentiation of HSFs in vitro by targeting TGF-ß2 to suppress the TGF-ß2/Smad pathway. Subsequently, the engineered exosomes encapsulating miR-141-3p (miR-141-3pOE -Exos) are isolated from adipose-derived mesenchymal stem cells transfected with Lv-miR-141-3p. MiR-141-3pOE -Exos show the same inhibitive effects as miR-141-3p mimics on the pathological behaviors of HSFs in vitro. The DMNAs for sustained release of miR-141-3pOE -Exos are further fabricated in vivo. MiR-141OE -Exos@DMNAs effectively decrease the thickness of HS and improve fibroblast distribution and collagen fiber arrangement, and downregulate the expression of α-SMA, COL-1, FN, TGF-ß2, and p-Smad2/3 in the HS tissue. Overall, a promising, effective, and convenient exosome@DMNA-based miRNA delivery strategy for HS treatment is provided.

P-MSC-derived extracellular vesicles facilitate diabetic wound healing via miR-145-5p/ CDKN1A-mediated functional improvements of high glucose-induced senescent fibroblasts.

Background: Persistent hyperglycaemia in diabetes causes functional abnormalities of human dermal fibroblasts (HDFs), partially leading to delayed skin wound healing. Extracellular vesicles (EVs) containing multiple pro-healing microRNAs (miRNAs) have been shown to exert therapeutic effects on diabetic wound healing. The present study aimed to observe the effects of EVs derived from placental mesenchymal stem cells (P-MSC-EVs) on diabetic wound healing and high glucose (HG)-induced senescent fibroblasts and to explore the underlying mechanisms. Methods: P-MSC-EVs were isolated by differential ultracentrifugation and locally injected into the full-thickness skin wounds of diabetic mice, to observe the beneficial effects on wound healing in vivo by measuring wound closure rates and histological analysis. Next, a series of assays were conducted to evaluate the effects of low (2.28 x 1010 particles/ml) and high (4.56 x 1010 particles/ml) concentrations of P-MSC-EVs on the senescence, proliferation, migration, and apoptosis of HG-induced senescent HDFs in vitro. Then, miRNA microarrays and real-time quantitative PCR (RT-qPCR) were carried out to detect the differentially expressed miRNAs in HDFs after EVs treatment. Specific RNA inhibitors, miRNA mimics, and small interfering RNA (siRNA) were used to evaluate the role of a candidate miRNA and its target genes in P-MSC-EV-induced improvements in the function of HG-induced senescent HDFs. Results: Local injection of P-MSC-EVs into diabetic wounds accelerated wound closure and reduced scar widths, with better-organized collagen deposition and decreased p16INK4a expression. In vitro, P-MSC-EVs enhanced the antisenescence, proliferation, migration, and antiapoptotic abilities of HG-induced senescent fibroblasts in a dose-dependent manner. MiR-145-5p was found to be highly enriched in P-MSC-EVs. MiR-145-5p inhibitors effectively attenuated the P-MSC-EV-induced functional improvements of senescent fibroblasts. MiR-145-5p mimics simulated the effects of P-MSC-EVs on functional improvements of fibroblasts by suppressing the expression of cyclin-dependent kinase inhibitor 1A and activating the extracellular signal regulated kinase (Erk)/protein kinase B (Akt) signaling pathway. Furthermore, local application of miR-145-5p agomir mimicked the effects of P-MSC-EVs on wound healing. Conclusions: These results suggest that P-MSC-EVs accelerate diabetic wound healing by improving the function of senescent fibroblasts through the transfer of miR-145-5p, which targets cyclin-dependent kinase inhibitor 1A to activate the Erk/Akt signaling pathway. P-MSC-EVs are promising therapeutic candidates for diabetic wound treatment.

Autophagosomes Defeat Ferroptosis by Decreasing Generation and Increasing Discharge of Free Fe2+ in Skin Repair Cells to Accelerate Diabetic Wound Healing.

Ferroptosis plays an essential role in the development of diabetes and its complications, suggesting potential therapeutic strategies targeting ferroptosis. Secretory autophagosomes (SAPs) carrying cytoplasmic cargoes have been recognized as novel nano-warrior to defeat diseases. Here, it is hypothesized that SAPs derived from human umbilical vein endothelial cells (HUVECs) can restore the function of skin repair cells by inhibiting ferroptosis to promote diabetic wound healing. High glucose (HG)-caused ferroptosis in human dermal fibroblasts (HDFs) is observed in vitro, which results in impaired cellular function. SAPs successfully inhibit ferroptosis in HG-HDFs, thereby improving their proliferation and migration. Further research show that the inhibitory effect of SAPs on ferroptosis resulted from a decrease in endoplasmic reticulum (ER) stress-regulated generation of free ferrous ions (Fe2+ ) in HG-HDFs and an increase in exosome release to discharge free Fe2+ from HG-HDFs. Additionally, SAPs promote the proliferation, migration, and tube formation of HG-HUVECs. Then the SAPs are loaded into gelatin-methacryloyl (GelMA) hydrogels to fabricate functional wound dressings. The results demonstrate the therapeutic effect of Gel-SAPs on diabetic wounds by restoring the normal behavior of skin repair cells. These findings suggest a promising SAP-based strategy for the treatment of ferroptosis-associated diseases.

Novel neutrophil extracellular trap-related mechanisms in diabetic wounds inspire a promising treatment strategy with hypoxia-challenged small extracellular vesicles.

Neutrophil extracellular traps (NETs) have been considered a significant unfavorable factor for wound healing in diabetes, but the mechanisms remain unclear. The therapeutic application of small extracellular vesicles (sEVs) derived from mesenchymal stem cells (MSCs) has received considerable attention for their properties. Hypoxic preconditioning is reported to enhance the therapeutic potential of MSC-derived sEVs in regenerative medicine. Therefore, the aim of this study is to illustrate the detailed mechanism of NETs in impairment of diabetic wound healing and develop a promising NET-targeting treatment based on hypoxic pretreated MSC-derived sEVs (Hypo-sEVs). Excessive NETs were found in diabetic wounds and in high glucose (HG)-induced neutrophils. Further research showed that high concentration of NETs impaired the function of fibroblasts through activating endoplasmic reticulum (ER) stress. Hypo-sEVs efficiently promoted diabetic wound healing and reduced the excessive NET formation by transferring miR-17-5p. Bioinformatic analysis and RNA interference experiment revealed that miR-17-5p in Hypo-sEVs obstructed the NET formation by targeting TLR4/ROS/MAPK pathway. Additionally, miR-17-5p overexpression decreased NET formation and overcame NET-induced impairment in fibroblasts, similar to the effects of Hypo-sEVs. Overall, we identify a previously unrecognized NET-related mechanism in diabetic wounds and provide a promising NET-targeting strategy for wound treatment.

Tunable Pt-Ni Interaction Induced Construction of Disparate Atomically Dispersed Pt Sites for Acidic Hydrogen Evolution.

Developing cost-effective Pt-based electrocatalysts for the hydrogen evolution reaction (HER) is highly urgent. Herein, we report novel electrocatalysts with individually dispersed Pt active sites and tunable Pt-Ni interaction decorated on carbon-wrapped nanotube frameworks (Pt/Ni-DA). Pt/Ni-DA exhibits superior HER performance at low Pt concentrations with an ultralow overpotential of 18 mV at 10 mA cm-2 and an ultrahigh mass activity of 2.13 A mgPt-1 at an overpotential of 50 mV, which is about four times higher than that of commercial Pt/C. X-ray absorption fine structure (XAFS) confirms the extension of Pt from the Ni surface to the Ni bulk phase. Mechanistic research and density functional theory (DFT) calculations collectively reveal that the dispersibility and distribution of Pt atoms in Ni regulate the electronic configuration of Pt sites, optimizing the binding energy of reaction intermediates and facilitating electron transfer during the HER process. This work highlights the importance of the electronic structure alternation through the accommodation effect toward enhanced catalytic performance in HER.

Transplantation of Umbilical Cord-Derived Mesenchymal Stem Cells Attenuates Surgical Wound-Induced Blood-Brain Barrier Dysfunction in Mice.

Blood-brain barrier (BBB) is the most important component of central nervous system (CNS) to keep toxins and pathogens from CNS. Although our studies demonstrated that using interleukin-6 antibodies (IL-6-AB) reversed the increased permeability of BBB, IL-6-AB is limited in their application that only could be used a few hours before surgery and seemed delayed the surgical wounds healing process, which urges us to find another more effective method. In this study, we employed the C57BL/6J female mice to investigate the potential effects of umbilical cord-derived mesenchymal stem cells (UC-MSCs) transplantation on BBB dysfunction induced by surgical wound. Compared to IL-6-AB, the transplantation of UC-MSCs more effectively decreased the BBB permeability after surgical wound evaluated by dextran tracer (immunofluorescence imaging and luorescence quantification). In addition, UC-MSCs can largely decrease the ratio of proinflammatory cytokine IL-6 to the anti-inflammatory cytokine IL-10 in both serum and brain tissue after surgical wound. Moreover, UC-MSCs successfully increased the levels of tight junction proteins (TJs) in BBB such as ZO-1, Occludin, and Claudin-5 and extremely decreased the level of matrix metalloproteinase-9 (MMP-9). Interestingly, UC-MSCs treatment also had positive effects on wound healing while protecting the BBB dysfunction induced by surgical wound compared to IL-6-AB treatment. These findings suggest that UC-MSCs transplantation is a highly efficient and promising approach on protecting the integrity of BBB which caused by peripheral traumatic injuries.

Therapeutic effects of mesenchymal stem cells and their derivatives in common skin inflammatory diseases: Atopic dermatitis and psoriasis.

Chronic skin inflammatory diseases including atopic dermatitis (AD) and psoriasis have been considered uncontrolled inflammatory responses, which have usually troubled patients around the world. Moreover, the recent method to treat AD and psoriasis has been based on the inhibition, not regulation, of the abnormal inflammatory response, which can induce a number of side effects and drug resistance in long-term treatment. Mesenchymal stem/stromal cells (MSCs) and their derivatives have been widely used in immune diseases based on their regeneration, differentiation, and immunomodulation with few adverse effects, which makes MSCs a promising treatment for chronic skin inflammatory diseases. As a result, in this review, we aim to systematically discuss the therapeutic effects of various resources of MSCs, the application of preconditioning MSCs and engineering extracellular vesicles (EVs) in AD and psoriasis, and the clinical evaluation of the administration of MSCs and their derivatives, which can provide a comprehensive vision for the application of MSCs and their derivatives in future research and clinical treatment.

Immunomodulatory potential of mesenchymal stem cell-derived extracellular vesicles: Targeting immune cells.

Various intractable inflammatory diseases caused by disorders of immune systems have pressed heavily on public health. Innate and adaptive immune cells as well as secreted cytokines and chemokines are commanders to mediate our immune systems. Therefore, restoring normal immunomodulatory responses of immune cells is crucial for the treatment of inflammatory diseases. Mesenchymal stem cell derived extracellular vesicles (MSC-EVs) are nano-sized double-membraned vesicles acting as paracrine effectors of MSCs. MSC-EVs, containing a variety of therapeutic agents, have shown great potential in immune modulation. Herein, we discuss the novel regulatory functions of MSC-EVs from different sources in the activities of innate and adaptive immune cells like macrophages, granulocytes, mast cells, natural killer (NK) cells, dendritic cells (DCs) and lymphocytes. Then, we summarize the latest clinical trials of MSC-EVs in inflammatory diseases. Furthermore, we prospect the research trend of MSC-EVs in the field of immune modulation. Despite the fact that the research on the role of MSC-EVs in regulating immune cells is in infancy, this cell-free therapy based on MSC-EVs still offers a promising solution for the treatment of inflammatory diseases.

Image-based features in machine learning to identify delivery errors and predict error magnitude for patient-specific IMRT quality assurance.

OBJECTIVE: To identify delivery error type and predict associated error magnitude by image-based features using machine learning (ML). METHODS: In this study, a total of 40 thoracic plans (including 208 beams) were selected, and four error types with different magnitudes were introduced into the original plans, including 1) collimator misalignment (COLL), 2) monitor unit (MU) variation, 3) systematic multileaf collimator misalignment (MLCS), and 4) random MLC misalignment (MLCR). These dose distributions of portal dose predictions for the original plans were defined as the reference dose distributions (RDD), while those for the error-introduced plans were defined as the error-introduced dose distributions (EDD). Both distributions were calculated for all beams with portal dose image prediction (PDIP). Besides, 14 image-based features were extracted from RDD and EDD of portal dose predictions to obtain the feature vectors. In addition, a random forest was adopted for the multiclass classification task, and regression prediction for error magnitude. RESULTS: The top five features extracted with the highest weight included 1) the relative displacement in the x direction, 2) the ratio of the absolute minimum residual error to the maximal RDD value, 3) the product of the maximum and minimum residuals, 4) the ratio of the absolute maximum residual error to the maximal RDD value, and 5) the ratio of the absolute mean residual value to the maximal RDD value. The relative displacement in the x direction had the highest weight. The overall accuracy of the five-class classification model was 99.85% for the validation set and 99.30% for the testing set. This model could be applied to the classification of the error-free plan, COLL, MU, MLCS, and MLCR with an accuracy of 100%, 98.4%, 99.9%, 98.0%, and 98.3%, respectively. MLCR had the worst performance in error magnitude prediction (70.1-96.6%), while others had better performance in error magnitude prediction (higher than 93%). In the error magnitude prediction, the mean absolute error (MAE) between predicted error magnitude and actual error ranged from 0.03 to 0.33, with the root mean squared error (RMSE) varying from 0.17 to 0.56 for the validation set. The MAE and RMSE ranged from 0.03 to 0.50 and 0.44 to 0.59 for the test set, respectively. CONCLUSION: It could be demonstrated in this study that the image-based features extracted from RDD and EDD can be employed to identify different types of delivery errors and accurately predict error magnitude with the assistance of ML techniques. They can be used to associate traditional gamma analysis with clinically based analysis for error classification and magnitude prediction in patient-specific IMRT quality assurance.

MiR146a-loaded engineered exosomes released from silk fibroin patch promote diabetic wound healing by targeting IRAK1.

Unhealable diabetic wounds need to be addressed with the help of newer, more efficacious strategies. Exosomes combined with biomaterials for sustained delivery of therapeutic agents are expected to bring new hope for chronic wound treatment. Here, the engineered exosomes modified for efficiently loading miR146a and attaching to silk fibroin patch (SFP) were demonstrated to promote diabetic wound healing. Silk fibroin binding peptide (SFBP) was screened through phage display, and SFBP-Gluc-MS2 (SGM) and pac-miR146a-pac fusion protein were constructed. The designed exosomes (SGM-Exos, miR146a-Exos, and SGM-miR146a-Exos) were isolated from the engineered placental mesenchymal stem cells (PMSCs) transduced with SGM or/and pac-miR146a-pac protein. Gluc signals indicated SGM-Exo@SFP markedly increased the binding rate and the stability of SGM-Exo. Moreover, the loading efficiency of miR146a in SGM-miR146a-Exos was ten-fold higher than that in miR146a-Exos. Superior to untreated, SGM-miR146a-Exo-only treated, and SFP-only treated groups, SGM-miR146a-Exo@SFP drived wound healing associated with less inflammation, collagen deposition, and neovascularization. The transcriptomics analysis suggested anti-inflammatory and regenerative effects with SGM-miR146a-Exo@SFP treatment. Here, we show efficient exosome@biomaterial-based miRNA delivery systems for regenerative medicine and tissue engineering.

Gelatin methacryloyl (GelMA) loaded with concentrated hypoxic pretreated adipose-derived mesenchymal stem cells(ADSCs) conditioned medium promotes wound healing and vascular regeneration in aged skin.

BACKGROUND: Aging skin is characterized by a disturbed structure and lack of blood supply, which makes it difficult to heal once injured. ADSCs secrete large amounts of cytokines, which promote wound healing and vascular regeneration through paracrine secretion, and the number of cytokines can be elevated by hypoxic pretreating. However, the components of ADSCs are difficult to retain in wounds. Gelatin methacrylate (GelMA) is a photopolymerizable hydrogel synthesized from gelatin and has recently emerged as a potentially attractive material for tissue engineering applications. GelMA loaded with concentrated hypoxic pretreated ADSCs conditioned medium could provide a new method of treating wounds in aged skin. METHODS: Primary ADSCs were isolated from human adipose tissue and characterized by flow cytometry and differentiation test. ADSCs in passages 4-6 were pretreated in the hypoxic and normoxic environments to collect conditioned medium, the conditioned medium was then concentrated to prepare concentrated ADSCs conditioned medium(cADSC-CM)(the one collected from ADSCs under hypoxia was called hypo-CM ,and the one from normoxia was called nor-CM). The concentration of cytokines was detected. After treated with cADSC-CM, the abilities of proliferation, migration, and tube formation of human umbilical vascular endothelial cells (HUVECs) were assayed, and Akt/mTOR and MAPK signal pathway was detected using western blotting. GelMA+hypo-CM hydrogel was prepared, and a comprehensive evaluation of morphology, protein release efficiency, degradation rate, mechanical properties, and rheology properties were performed. Full-thickness skin wounds were created on the backs of 20-month-old mice. After surgery, GelMA, GelMA+F12, GelMA+hypo-CM, and GelMA+nor-CM were applied to the wound surface respectively. H&E, Masson, and immunohistochemistry staining were performed, and a laser Doppler perfusion imager was used to evaluate the blood perfusion. The student's t-test was used for analysis between two groups and a one-way analysis of variance (ANOVA) was used for analysis among multi groups. RESULTS: Our results revealed that 1) wounds in aged skin healed more slowly than that in young skin and exhibited poorer perfusion; 2) hypoxic pretreated ADSCs secreted more cytokines including VEGF by activating HIF1α; 3) hypo-CM promoted proliferation and migration of HUVECs through VEGF/Akt/mTOR and MAPK signal pathway; 4) GelMA-hypoCM accelerated wound healing and angiogenesis in aged skin in vivo. CONCLUSION: GelMA loaded with concentrated hypoxic pretreated adipose-derived mesenchymal stem cells conditioned medium could accelerate wound healing in aged skin by promoting angiogenesis.

Availability, Functionality, and Safety as well as Quality Control of Hepatocytes as Seeding Cells in Liver Regenerative Medicine: State of the Art and Challenges.

Hepatic disease is one of the most common causes of death worldwide and has become a global health problem. Liver transplantation is the only effective treatment strategy for patients with hepatic function failure, but the insufficient number of donated healthy livers is the main obstacle limiting this process. To alleviate the demand for donor's livers, alternative approaches are being actively explored using liver tissue engineering principles. Liver tissue engineering consists of three elements, including seeding cells, extracellular matrix, and bioreactors. Among them, seeding cell is the most key factor. In this regard, hepatocyte-based tissue engineering can overcome the above shortages for tissue repair and regeneration in hepatic disorders. Primary human hepatocytes in liver regenerative medicine are the most preferred seeding cells, although limited access to a sufficient number of functional hepatocytes are a major issue due to the difficulties in long-term function maintenance of hepatocyte as well as the lack of availability of healthy donors. Hepatocyte-like cells (HLCs), derived from various stem cells, including non-liver-derived stem cells and liver-derived stem cells, as well as trans-differentiation of other cell types, may provide adequate cell sources and could replace primary human hepatocytes as seeding cells. However, it is still a great difficulty that HLCs generated by stem cell differentiation meet the quality required for clinical therapy. Furthermore, none of the standardized protocols to generate high-quality HLCs is available. Whether primary hepatocytes or HLCs are from various sources, preventing the functional deterioration of hepatocytes or generating fully functional hepatocytes is also a big challenge, respectively. In addition, the adoptions of three-dimensional co-culture systems and some small-molecule compounds contribute to maintaining the hepatic functionality of primary hepatocytes and enhancing the liver-specific functions of HLCs. In short, hepatocyte-based liver regenerative medicine is an attractive alternative strategy for liver diseases, notwithstanding some challenges still exist from bench to bedside. This review summarizes the current status, issues, and challenges in availability, functionality, and safety, as well as quality control of seeding hepatocytes with regard to liver tissue engineering in regenerative medicine for the treatment of liver disorders.