A Biomimetic 3D-Self-Forming Approach for Microvascular Scaffolds

The development of science and technology often drew lessons from natural phenomena. Herein, inspired by drying-driven curling of apple peels, hydrogel-based micro-scaled hollow tubules (MHTs) are proposed for biomimicking microvessels, which promote microcirculation and improve the survival of random skin flaps. MHTs with various pipeline structures are fabricated using hydrogel in corresponding shapes, such as Y-branches, anastomosis rings, and triangle loops. Adjustable diameters can be achieved by altering the concentration and cross-linking time of the hydrogel. Based on this rationale, biomimetic microvessels with diameters of 50-500 mu m are cultivated in vitro by coculture of MHTs and human umbilical vein endothelial cells. In vivo studies show their excellent performance to promote microcirculation and improve the survival of random skin flaps. In conclusion, the present work proposes and validifies a biomimetic 3D self-forming method for the fabrication of biomimetic vessels and microvascular scaffolds with high biocompatibility and stability based on hydrogel materials, such as gelatin and hyaluronic acid.Peer reviewe

A Biomimetic 3D-Self-Forming Approach for Microvascular Scaffolds

The development of science and technology often drew lessons from natural phenomena. Herein, inspired by drying-driven curling of apple peels, hydrogel-based micro-scaled hollow tubules (MHTs) are proposed for biomimicking microvessels, which promote microcirculation and improve the survival of random skin flaps. MHTs with various pipeline structures are fabricated using hydrogel in corresponding shapes, such as Y-branches, anastomosis rings, and triangle loops. Adjustable diameters can be achieved by altering the concentration and cross-linking time of the hydrogel. Based on this rationale, biomimetic microvessels with diameters of 50-500 mu m are cultivated in vitro by coculture of MHTs and human umbilical vein endothelial cells. In vivo studies show their excellent performance to promote microcirculation and improve the survival of random skin flaps. In conclusion, the present work proposes and validifies a biomimetic 3D self-forming method for the fabrication of biomimetic vessels and microvascular scaffolds with high biocompatibility and stability based on hydrogel materials, such as gelatin and hyaluronic acid

Biogenerated Oxygen‐Related Environmental Stressed Apoptotic Vesicle Targets Endothelial Cells

Abstract The dynamic balance between hypoxia and oxidative stress constitutes the oxygen‐related microenvironment in injured tissues. Due to variability, oxygen homeostasis is usually not a therapeutic target for injured tissues. It is found that when administered intravenously, mesenchymal stem cells (MSCs) and in vitro induced apoptotic vesicles (ApoVs) exhibit similar apoptotic markers in the wound microenvironment where hypoxia and oxidative stress co‐existed, but MSCs exhibited better effects in promoting angiogenesis and wound healing. The derivation pathway of ApoVs by inducing hypoxia or oxidative stress in MSCs to simulate oxygen homeostasis in injured tissues is improved. Two types of oxygen‐related environmental stressed ApoVs are identified that directly target endothelial cells (ECs) for the accurate regulation of vascularization. Compared to normoxic and hypoxic ones, oxidatively stressed ApoVs (Oxi‐ApoVs) showed the strongest tube formation capacity. Different oxygen‐stressed ApoVs deliver similar miRNAs, which leads to the broad upregulation of EC phosphokinase activity. Finally, local delivery of Oxi‐ApoVs‐loaded hydrogel microspheres promotes wound healing. Oxi‐ApoV‐loaded microspheres achieve controlled ApoV release, targeting ECs by reducing the consumption of inflammatory cells and adapting to the proliferative phase of wound healing. Thus, the biogenerated apoptotic vesicles responding to oxygen‐related environmental stress can target ECs to promote vascularization

Progress of laser and light treatments for lower eyelid rejuvenation

Laser and light treatments have recently become popular owing to its efficacy in treating laxity, rhytids, hyperpigmentation of the lower eyelids, and drooping of septum fat. For several decades, our department has explored the application of laser and light treatment for eye rejuvenation. This paper summarizes common treatment methods and analyzes the published literature on the indications and outcomes of multiple laser and light treatments for lower eyelid rejuvenation. An extensive survey of peer-reviewed literature was performed using PubMed, with the search terms “noninvasive treatment”, “infraorbital”, “palpebral bags”, “lower eyelid”, “radiofrequency (RF)”, “laser”, “nonsurgical skin tightening”, and “noninvasive fat reduction”. The results showed that the use of lasers, intense pulsed light (IPL), monopolar RF, bipolar RF, AdipoLASER rejuvenation (ALJ), and fractional RF microneedling are safe and effective treatments for palpebral bags. We conclude that using Q-switched lasers, IPL, RF, ALJ, and fractional RF microneedling is safe and effective for lower eyelid rejuvenation, with minimal complications and quick recovery. Further research and development of optoelectronic therapy may encourage breakthroughs in lower eyelid treatment, such as simplified complex surgery and noninvasive methods

Biomaterial Scaffolds for Improving Vascularization During Skin Flap Regeneration

SUMMARY: Over the past few decades, biomaterials have made rapid advances in tissue engineering.In particular, there have been several studies on vascularization during skin flap regeneration for plastic surgery. From the perspective of function, the biomaterials used to improve the vascularization of skin flaps are primarily classified into two types: (1) electrospun nanofibrous membranes as porous scaffolds, and (2) hydrogels as cell or cytokine carriers. Based on their source, various natural, synthetic, and semi-synthetic biomaterials have been developed with respective characteristics. For the ischemic environment of the flap tissue, the therapeutic effect of the combination of biomaterials was better than that of drugs, cytokines, and cells alone. Biomaterials could improve cell migration, prolong the efficacy of cytokines, and provide an advantageous survival environment to transplanted cells

Revealing the Distribution of Aggregation-Induced Emission Nanoparticles via Dual-Modality Imaging with Fluorescence and Mass Spectrometry

Aggregation-induced emission nanoparticles (AIE NPs) are widely used in the biomedical field. However, understanding the biological process of AIE NPs via fluorescence imaging is challenging because of the strong background and poor penetration depth. Herein, we present a novel dual-modality imaging strategy that combines fluorescence imaging and label-free laser desorption/ionization mass spectrometry imaging (LDI MSI) to map and quantify the biodistribution of AIE NPs (TPAFN-F127 NPs) by monitoring the intrinsic photoluminescence and mass spectrometry signal of the AIE molecule. We discovered that TPAFN-F127 NPs were predominantly distributed in the liver and spleen, and most gradually excreted from the body after 5 days. The accumulation and retention of TPAFN-F127 NPs in tumor sites were also confirmed in a tumor-bearing mouse model. As a proof of concept, the suborgan distribution of TPAFN-F127 NPs in the spleen was visualized by LDI MSI, and the results revealed that TPAFN-F127 NPs were mainly distributed in the red pulp of the spleen with extremely high concentrations within the marginal zone. The in vivo toxicity test demonstrated that TPAFN-F127 NPs are nontoxic for a long-term exposure. This dual-modality imaging strategy provides some insights into the fine distribution of AIE NPs and might also be extended to other polymeric NPs to evaluate their distribution and drug release behaviors in vivo

Biomedical applications of Janus membrane

The traditional membrane with single structure cannot satisfy complex clinical applications. Inspired by lotus leaf, a novel structure Janus membrane has achieved more attention recently. Janus membrane is a membrane structure which has two faces with opposite properties. This special structure endows it with asymmetric surface wettability, which can provide an intrinsic driving force to transport along a specified direction, thus achieve unidirectional liquid transport and selective liquid separation. Janus membrane has a promising future, and has been widely used in chemical fields such as self-cleaning, oil/water separation, mist collection, and desalination, while less studied in biomedical field. In this review, the biomedical applications especially in different stages of wound healing process, current challenges in fabrication process and future perspectives of Janus membranes in practical applications under different Janus models, such as hemostasis, bone regeneration, blood cell isolation and gastric mycosal defect will be discussed. It is expected that this unique structure can provide a good therapy prospect in biomedical fields

The Variance of Photophysical Properties of Tetraphenylethene and Its Derivatives during Their Transitions from Dissolved States to Solid States

The study of aggregation-induced emission luminogens (AIEgens) shows promising perspectives explored in lighting, optical sensors, and biological therapies. Due to their unique feature of intense emissions in aggregated solid states, it smoothly circumvents the weaknesses in fluorescent dyes, which include aggregation-caused quenching of emission and poor photobleaching character. However, our present knowledge of the AIE phenomena still cannot comprehensively explain the mechanism behind the substantially enhanced emission in their aggregated solid states. Herein, to systematically study the mechanism, the typical AIEgens tetraphenylethene (TPE) was chosen, to elucidate its photophysical properties, the TPE in THF/H2O binary solvents, TPE in THF solvents depending on concentration, and the following direct conversion from a dissolved state to a precipitated solid state were analyzed. Moreover, the TPE derivatives were also investigated to supply more evidence to better decipher the generally optical behaviors of TPE and its derivatives. For instance, the TPE derivative was homogeneously dispersed into tetraethyl orthosilicate to monitor the variance of photophysical properties during sol–gel processing. Consequently, TPE and its derivatives are hypothesized to abide by the anti-Kasha rule in dissolved states. In addition, the factors primarily influencing the nonlinear emission shifting of TPE and its derivatives are also discussed

Stem cells for organoids

Abstract Organoids are three‐dimensional (3D) cell culture systems that simulate the structures and functions of organs, involving applications in disease modeling, drug screening, and cellular developmental biology. The material matrix in organoids can provide a 3D environment for stem cells to differentiate into different cell types and continuously self‐renew, thereby realizing the in vitro culture of organs, which has received extensive attention in recent years. However, some challenges still exist in organoids, including low maturity, high heterogeneity, and lack of spatiotemporal regulation. Therefore, in this review, we summarized the culturing protocols and various applications of stem cell‐derived organoids and proposed insightful thoughts for engineering stem cells into organoids in view of the current shortcomings, to achieve the further application and clinical translation of stem cells and engineered stem cells in organoid research

Regulated extravascular microenvironment via reversible thermosensitive hydrogel for inhibiting calcium influx and vasospasm

Arterial vasospasm after microsurgery can cause severe obstruction of blood flow manifested as low tissue temperature, leading to tissue necrosis. The timely discovery and synchronized treatment become pivotal. In this study, a reversible, intelligent, responsive thermosensitive hydrogel system is constructed employing both the gel–sol transition and the sol–gel transition. The “reversible thermosensitive (RTS)” hydrogel loaded with verapamil hydrochloride is designed to dynamically and continuously regulate the extravascular microenvironment by inhibiting extracellular calcium influx. After accurate implantation and following in situ gelation, the RTS hydrogel reverses to the sol state causing massive drug release to inhibit vasospasm when the tissue temperature drops to the predetermined transition temperature. Subsequent restoration of the blood supply alleviates further tissue injury. Before the temperature drops, the RTS hydrogel maintains the gel state as a sustained-release reservoir to prevent vasospasm. The inhibition of calcium influx and vasospasm in vitro and in vivo is demonstrated using vascular smooth muscle cells, mice mesenteric arterial rings, and vascular ultrasonic Doppler detection. Subsequent animal experiments demonstrate that RTS hydrogel can promote tissue survival and alleviate tissue injury responding to temperature change. Therefore, this RTS hydrogel holds therapeutic potential for diseases requiring timely detection of temperature change