Advanced Functional Biomaterials for Stem Cell Delivery in Regenerative Engineering and Medicine

Stem cell–based therapies can potentially regenerate many types of tissues and organs, thereby providing solutions to a variety of diseases and injuries. However, acute cell death, uncontrolled differentiation, and low functional engraftment yields remain critical obstacles for clinical translation. Advanced functional biomaterial scaffolds that can deliver stem cells to the targeted tissues/organs and promote stem cell survival, differentiation, and integration to host tissues may potentially transform the clinical outcome of stem cell–based regenerative therapies. In this review, the authors briefly summarize sources of stem cells for transplantation, present the current state of the art in biomaterial design for stem cell delivery, and provide critical analysis for existing materials. Applications to the cardiovascular, neural, and musculoskeletal systems are highlighted with recent nonclinical studies and clinical trials. The authors also discuss how advances in biomaterials research can contribute to regenerative medicine research and stem cell therapies.     

A Multifunctional Polymeric Periodontal Membrane with Osteogenic and Antibacterial Characteristics

Periodontitis is a prevalent chronic, destructive inflammatory disease affecting tooth‐supporting tissues in humans. Guided tissue regeneration strategies are widely utilized for periodontal tissue regeneration generally by using a periodontal membrane. The main role of these membranes is to establish a mechanical barrier that prevents the apical migration of the gingival epithelium and hence allowing the growth of periodontal ligament and bone tissue to selectively repopulate the root surface. Currently available membranes have limited bioactivity and regeneration potential. To address such challenges, an osteoconductive, antibacterial, and flexible poly(caprolactone) (PCL) composite membrane containing zinc oxide (ZnO) nanoparticles is developed. The membranes are fabricated through electrospinning of PCL and ZnO particles. The physical properties, mechanical characteristics, and in vitro degradation of the engineered membrane are studied in detail. Also, the osteoconductivity and antibacterial properties of the developed membrane are analyzed in vitro. Moreover, the functionality of the membrane is evaluated with a rat periodontal defect model. The results confirmed that the engineered membrane exerts both osteoconductive and antibacterial properties, demonstrating its great potential for periodontal tissue engineering.     

大鼠坐骨神经再生过程中的神经元轴突自噬作用

目的：探讨大鼠坐骨神经变性轴突清除中的自噬作用。方法：横切大鼠坐骨神经制作wallerian变性模型,造模后不同时间点取远断端组织行电镜结构观察和酸性磷酸酶(AcPase)活性检测。结果：坐骨神经横切后轴突发生变性,主要变化为术后第5h～2d轴质肿胀,轴突与髓鞘分离,术后第4d轴质浓缩,轴突与髓鞘完全分离形成游离轴突体。术后初期变性轴突主要形成大小不等的空泡,后期轴突与髓鞘完全分离并形成较大的游离轴突体,轴突体外包一层轴突膜是神经元细胞膜的延续,轴突体轴质浓缩,含大量各级自噬泡和纵横交错的神经丝、微管和微丝。经酸性磷酸酶(AcPase)染色证实自噬泡均呈AcPase阳性,第7d后轴突体被降解吸收,形成的空腔内偶见巨噬细胞。结论：大鼠坐骨神经再生过程中变性轴突的清除主要靠轴突自身的自噬和施万细胞吞噬机制,而巨噬细胞只起辅助作用。     

Multifunctional DNA Hydrogels with Hydrocolloid-Cotton Structure for Regeneration of Diabetic Infectious Wounds

Currently, diabetic infectious wound treatments remain a significant challenge for regenerative medicine due to the unicity of clinical dressings, which lack systemic multifunctional wound dressings with high absorbability, customizable shape, rapid self-healing, guiding tissue regeneration, and restoring physiological functions. Here, a multifunctional DNA hydrogel is conveniently obtained through grafting DNA units and polyethyleneimine dynamic cross-linking and doped heating function black phosphorus quantum dots. The obtained DNA hydrogel features excellent exudate absorption performance, adjustable heating ability, mechanical behavior, self-healing ability, writability, tissue adhesion, and antibacterial properties. The incorporation of procyanidin B2 (OPC B2) endows the DNA hydrogels with renowned scavenging free radicals and antioxidant properties. Furthermore, the DNA hydrogel dressing can promote the transformation of macrophages from pro-inflammatory M1 into repairing M2 phenotype, keeping the wound in a stable remodeled state. Astonishingly, the DNA hydrogel dressing can activate neurons to transform into a repair state, accelerating skin nerve regeneration and angiogenesis. Beyond that, it can recruit myeloid cells to activate the adaptive immune response, enhancing the ability of DNA hydrogel dressing to promote tissue regeneration, thereby promoting hair follicle and hair regeneration. Therefore, this advanced collaborative strategy provides an effective method for cascade management of clinical guided tissue regeneration.     

PCB铜蚀刻废液的治理概述

概述了PCB铜蚀刻废液的传统治理方法并对其防治效果进行了分析。此外,介绍了一种新型治理技术——铜蚀刻废液的循环再生技术。     

Micro/Nanometer‐Structured Scaffolds for Regeneration of Both Cartilage and Subchondral Bone

Treatment of osteochondral defects remains a great challenge in clinical practice because cartilage and subchondral bone possess significantly different physiological properties. In this study, the controlled surface micro/nanometer structure of bioactive scaffolds in a combination of biomaterial chemistry is harnessed to address this issue. Model bioactive biomaterials, bredigite (BRT) scaffolds, with controlled surface micro/nanostructure are successfully fabricated by combining 3D printing with a hydrothermal process. It is found that the growth of micro/nano–calcium phosphate crystals on the surface of BRT scaffolds notably enhances their compressive strength by healing the microcracks on the strut surface. The micro/nanostructured surface distinctly facilitates the spread and differentiation of chondrocytes by activating integrin αvb1 and α5b1 heterodimers, regulates cell morphology, and promotes osteogenic differentiation of rabbit bone marrow stromal cells (rBMSCs) through the synergetic effect of integrin α5b1 and RhoA, in which the microrod surface demonstrates the highest stimulatory effect on the differentiation of chondrocytes and rBMSCs. The in vivo study shows that the micro/nanostructured surface of the 3D printed scaffolds obviously promotes the regeneration of both cartilage and subchondral bone tissues. This study suggests that the construction of controlled micro/nanostructured surface in porous 3D scaffolds offers a smart strategy to induce bilineage bioactivities for osteochondral regeneration.     

基于主动锁模控制的激光谐波研究

介绍一种采用主动锁模控制产生超短激光脉冲序列的方法。首先通过基于主动锁模激光系统的参量自治微分方程思想,导出了系统出现稳定条件时参数设置方法。然后利用铌酸锂的非线性,展开成贝赛尔系数的函数级数,载频与边频数差为调制频率的整数倍,最后产生高重复频率超短光脉冲,得到高阶锁模脉冲,实验结果表明:其通过调节调制器的调制参数来控制谐振腔中的模式损耗,在调制频率为１ＧＨz量级的情况下,可获得重复频率１０ＧＨz的超短光脉冲序列,有啁啾时脉冲时域形状是很好的高斯型,没有出现明显畸变。     

Bioinspired Development of an In Vitro Engineered Fracture Callus for the Treatment of Critical Long Bone Defects

Cell-based regenerative constructs provide hope for the restoration of tissue function in compromised biological conditions such as complex bone defects. A strategy mimicking the cascade of events of postnatal fracture healing suggests an implant design where progenitor cells provide the driving force for the construct's tissue forming capacity, while framing biomaterials provide cells with 3D cues to direct cellular processes. Large bone defects mainly heal through the formation of an intermediate endochondral fracture callus. The authors aimed to develop an in vitro engineered fracture callus manufactured by bioprinting to provide a spatially organized tissue construct based on: i) in vitro 3D primed human periosteum derived cells and ii) biocompatible thiol-ene alginate hydrogels, mimicking the cells and extracellular matrix present in the different zones of the callus. Cell viability and maintained osteochondrogenic differentiation upon bioprinting is confirmed in vitro. In vivo assessment displays that the developed biomaterials provided essential 3D cues that further guided the cells in their tissue forming process in the absence of additional stimulatory molecules. The reported findings confirm the appeal of a biomimetic approach to steer tissue development of in vitro engineered constructs and illustrate the suitability of bioprinting methodologies for the fabrication of living regenerative implants.     

单片机在小型空气干燥器中的应用

介绍了单片机应用于空气干燥器中的一种设计方法。该干燥器具有自动化程度高、安全性好、可靠性高、使用方便、再生工艺先进等特点。