Huilin Yang

Over the last decade, adipose-derived stem cells (ADSCs) have attracted increasing attention in the field of regenerative medicine. ADSCs appear to be the most advantageous cell type for regenerative therapies owing to their easy accessibility, multipotency, and active paracrine activity. This review highlights current challenges in translating ADSC-based therapies into clinical settings and discusses novel strategies to overcome the limitations of ADSCs. To further establish ADSC-based therapies as an emerging platform for regenerative medicine, this review also provides an update on the advancements in this field, including fat grafting, wound healing, bone regeneration, skeletal muscle repair, tendon reconstruction, cartilage regeneration, cardiac repair, and nerve regeneration. ADSC-based therapies are expected to be more tissue-specific and increasingly important in regenerative medicine.

The strategies concerning modification of the complex immune pathological inflammatory environment during acute spinal cord injury remain oversimplified and superficial. Inspired by the acidic microenvironment at acute injury sites, a functional pH-responsive immunoregulation-assisted neural regeneration strategy was constructed. With the capability of directly responding to the acidic microenvironment at focal areas followed by triggered release of the IL-4 plasmid-loaded liposomes within a few hours to suppress the release of inflammatory cytokines and promote neural differentiation of mesenchymal stem cells in vitro, the microenvironment-responsive immunoregulatory electrospun fibers were implanted into acute spinal cord injury rats. Together with sustained release of nerve growth factor (NGF) achieved by microsol core-shell structure, the immunological fiber scaffolds were revealed to bring significantly shifted immune cells subtype to down-regulate the acute inflammation response, reduce scar tissue formation, promote angiogenesis as well as neural differentiation at the injury site, and enhance functional recovery in vivo. Overall, this strategy provided a delivery system through microenvironment-responsive immunological regulation effect so as to break through the current dilemma from the contradiction between immune response and nerve regeneration, providing an alternative for the treatment of acute spinal cord injury.

STUDY DESIGN: Large scale, cross-sectional imaging study of a general population. OBJECTIVES: To evaluate the prevalence, morphology, and distribution of ossification of the ligamentum flavum (OLF) in a population, and synthesize the scientific literature on the prevalence of OLF and some factors associated with its occurrence. SUMMARY OF BACKGROUND DATA: OLF is a rare disease in which the pathogenesis has not been conclusively established. Little is known about its epidemiology. To date, there is no study that comprehensively assessed the distribution and prevalence of OLF in the whole spine using magnetic resonance imaging (MRI). METHODS: A total of 1736 southern Chinese volunteers (1068 women; 668 men) between 8 and 88 years of age (mean, 38 years) were recruited by open invitation. MRI was administered to all the participants. T2-weighted, 5-mm spin-echo MRI sequences of the whole spine were obtained. Presence of OLF was identified as an area of low signal intensity in the T2 sagittal sequence located in the posterior part of the spinal canal, and subsequently confirmed by computed tomography scans showing areas of ossification within the ligamentum flavum. The distribution of OLF was classified into 3 types: the isolated type, continuous type, and noncontinuous type. While the morphology of the lesion was classified into triangular, round, and beak shapes based on the pattern of ossification on T2-weighted sagittal MRIs. RESULTS: OLF was identified in a total of 66 subjects or 3.8% of the population (52 women and 14 men). In 45(68.2%) cases, OLF was present at a single-level (isolated type), whereas in 21 (31.8%) cases OLF was present at multiple levels. The isolated type was found in 45 (68.2%) cases, continuous type in 11 (16.7%), and noncontinuous type in 10 (15.2%). The most common site of involvement is the lower thoracic spine, but they can also occur in the upper thoracic spine. The majority of the segments had a round morphology (n = 75: 81.5%), while 17 (18.5%) segments were triangular in shape. A literature review of the past 26 years showed only 4 reports on the prevalence of OLF, all were in special patient groups. CONCLUSION: Case reports have described postoperative paraplegia from failure to identify and decompress all stenotic segments of OLF. This study demonstrated that OLF is not uncommon, and that some 15% of the lesions are noncontinuous, and therefore could be missed. The authors recommend that for patients undergoing surgical decompression for 1 level of OLF, the whole spine should be routinely screened for other stenotic segments. Failure to do so could result in paraplegia from the nondecompressed levels.

Distal necrosis of random skin flap is always clinical problematic in plastic surgery. The development of 3D functional vascular networks is fundamental for the survival of a local random skin flap. Herein, an effective technique on constructing 3D fibrous scaffolds for accelerated vascularization is demonstrated using a photocrosslinkable natural hydrogel based on gelatin methacryloyl (GelMA) by electrospinning. It is found that the ultraviolet (UV) photocrosslinkable gelatin electrospun hydrogel fibrous membranes exhibit soft adjustable mechanical properties and controllable degradation properties. Furthermore, it is observed that the optimized hydrogel scaffolds can support endothelial cells and dermal fibroblasts adhesion, proliferation, and migration into the scaffolds, which facilitates vascularization. Importantly, a rapid formation of tubes is observed after 3 d seeding of endothelial cells. After GelMA fibrous scaffold implantation below the skin flap in a rat model, it is found that the flap survival rate is higher than the control group, and there is more microvascular formation, which is potentially beneficial for the flap tissue vascularization. These data suggest that GelMA hydrogels can be used for biomedical applications that require the formation of microvascular networks, including the development of complex engineered tissues.