3D printed collagen/silk fibroin scaffolds carrying the secretome of human umbilical mesenchymal stem cells ameliorated neurological dysfunction after spinal cord injury in rats.

Although implantation of biomaterials carrying mesenchymal stem cells (MSCs) is considered as a promising strategy for ameliorating neural function after spinal cord injury (SCI), there are still some challenges including poor cell survival rate, tumorigenicity and ethics concerns. The performance of the secretome derived from MSCs was more stable, and its clinical transformation was more operable. Cytokine antibody array demonstrated that the secretome of MSCs contained 79 proteins among the 174 proteins analyzed. Three-dimensional (3D) printed collagen/silk fibroin scaffolds carrying MSCs secretome improved hindlimb locomotor function according to the Basso-Beattie-Bresnahan scores, the inclined-grid climbing test and electrophysiological analysis. Parallel with locomotor function recovery, 3D printed collagen/silk fibroin scaffolds carrying MSCs secretome could further facilitate nerve fiber regeneration, enhance remyelination and accelerate the establishment of synaptic connections at the injury site compared to 3D printed collagen/silk fibroin scaffolds alone group according to magnetic resonance imaging, diffusion tensor imaging, hematoxylin and eosin staining, Bielschowsky's silver staining, immunofluorescence staining and transmission electron microscopy. These results indicated the implantation of 3D printed collagen/silk fibroin scaffolds carrying MSCs secretome might be a potential treatment for SCI.

Integrated printed BDNF/collagen/chitosan scaffolds with low temperature extrusion 3D printer accelerated neural regeneration after spinal cord injury.

Recent studies have shown that 3D printed scaffolds integrated with growth factors can guide the growth of neurites and promote axon regeneration at the injury site. However, heat, organic solvents or cross-linking agents used in conventional 3D printing reduce the biological activity of growth factors. Low temperature 3D printing can incorporate growth factors into the scaffold and maintain their biological activity. In this study, we developed a collagen/chitosan scaffold integrated with brain-derived neurotrophic factor (3D-CC-BDNF) by low temperature extrusion 3D printing as a new type of artificial controlled release system, which could prolong the release of BDNF for the treatment of spinal cord injury (SCI). Eight weeks after the implantation of scaffolds in the transected lesion of T10 of the spinal cord, 3D-CC-BDNF significantly ameliorate locomotor function of the rats. Consistent with the recovery of locomotor function, 3D-CC-BDNF treatment could fill the gap, facilitate nerve fiber regeneration, accelerate the establishment of synaptic connections and enhance remyelination at the injury site.

The corticospinal tract structure of collagen/silk fibroin scaffold implants using 3D printing promotes functional recovery after complete spinal cord transection in rats.

No effective treatment has been established for nerve dysfunction caused by spinal cord injury (SCI). Orderly axonal growth at the site of spinal cord transection and creation of an appropriate biological microenvironment are important for functional recovery. To axially guiding axonal growth, designing a collagen/silk fibroin scaffold fabricated with 3D printing technology (3D-C/SF) emulated the corticospinal tract. The normal collagen/silk fibroin scaffold with freeze-drying technology (C/SF) or 3D-C/SF scaffold were implanted into rats with completely transected SCI to evaluate its effect on nerve repair during an 8-week observation period. Electrophysiological analysis and locomotor performance showed that the 3D-C/SF implants contributed to significant improvements in the neurogolical function of rats compared to C/SF group. By magnetic resonance imaging, 3D-C/SF implants promoted a striking degree of axonal regeneration and connection between the proximal and distal SCI sites. Compared with C/SF group, rats with 3D-C/SF scaffold exhibited fewer lesions and disordered structures in histological analysis and more GAP43-positive profiles at the lesion site. The above results indicated that the corticospinal tract structure of 3D printing collagen/silk fibroin scaffold improved axonal regeneration and promoted orderly connections within the neural network, which could provided a promising and innovative approach for tissue repair after SCI.

Erratum to: Integrated printed BDNF/collagen/chitosan scaffolds with low temperature extrusion 3D printer accelerated neural regeneration after spinal cord injury.

[This corrects the article DOI: 10.1093/rb/rbab047.].

Injury-preconditioning secretome of umbilical cord mesenchymal stem cells amplified the neurogenesis and cognitive recovery after severe traumatic brain injury in rats.

Traumatic brain injury (TBI) is a dominant cause of death and permanent disability worldwide. Although TBI could significantly increase the proliferation of adult neural stem cells in the hippocampus, the survival and maturation of newborn cells is markedly low. Increasing evidence suggests that the secretome derived from mesenchymal stem cells (MSCs) would be an ideal alternative to MSC transplantation. The successive and microenvironmentally responsive secretion in MSCs may be critical for the functional benefits provided by transplanted MSCs after TBI. Therefore, it is reasonable to hypothesize that the signaling molecules secreted in response to local tissue damage can further facilitate the therapeutic effect of the MSC secretome. To simulate the complex microenvironment in the injured brain well, we used traumatically injured brain tissue extracts to pretreat umbilical cord mesenchymal stem cells (UCMSCs) in vitro and stereotaxically injected the secretome from traumatic injury-preconditioned UCMSCs into the dentate gyrus of the hippocampus in a rat severe TBI model. The results revealed that compared with the normal secretome, the traumatic injury-preconditioned secretome could significantly further promote the differentiation, migration, and maturation of newborn cells in the dentate gyrus and ultimately improve cognitive function after TBI. Cytokine antibody array suggested that the increased benefits of secretome administration were attributable to the newly produced proteins and up-regulated molecules from the MSC secretome preconditioned by a traumatically injured microenvironment. Our study utilized the traumatic injury-preconditioned secretome to amplify neurogenesis and improve cognitive recovery, suggesting this method may be a novel and safer candidate for nerve repair. Cover Image for this issue: doi: 10.1111/jnc.14741.

Intravenously Infusing the Secretome of Adipose-Derived Mesenchymal Stem Cells Ameliorates Neuroinflammation and Neurological Functioning After Traumatic Brain Injury.

The secretome of mesenchymal stem cell (MSC) offers a series of immunoregulatory properties and is regarded as an effective method of mitigating secondary neuroinflammation induced by traumatic brain injury (TBI). The secretome of adipose-derived MSCs (ASC-ST) was collected under hypoxia conditions. Proteomics data were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and concentrations of major components were tested. After the TBI caused by an electric cortical contusion impactor, rats were injected ASC-ST through caudal veins for 7 days. The neurological functional prognosis of TBI rats was significantly improved, and the vasogenic edema of brain tissues that was measured 14 days after TBI was relieved by ASC-ST, corresponding to brain water content levels. ASC-ST ameliorated TBI-induced neuroinflammatory environments that caused the edema, the apoptosis of the neural cells, and the nerve fiber damage by increasing the number of M2 phenotypes present while reducing the number of M1 phenotype microglia present. Furthermore, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) levels were reduced, whereas transforming growth factor-beta (TGF-ß) and tumor necrosis factor-stimulated gene 6 protein (TSG-6) levels were increased after secretome treatment. Altogether, ASC-ST is capable of improving neural functioning by modulating TBI-induced neuroinflammation and its related secondary insults. ASC-ST may be one of the most promising candidates for regulating the secondary inflammatory reactions of central nervous systems for clinical use.

[Preventive and therapeutic effects of safflower water extract on systemic scleroderma in mice and its mechanism].

OBJECTIVE: To study the preventive and therapeutic effects of safflower water extract on systemic scleroderma (SSc) in mice and its mechanism. METHODS: Sixty BALB/C mice were randomly divided into the control group, model group, prednisone group and safflower low, middle, high dose groups, 10 mice in each group.The control group was injected with normal saline, and the other five groups were subcutaneously injected with bleomycin hydrochloride with 100 µl at the concentration of 200 µg /ml on the back, once a day for 28 days to establish the SSc models.At the same time, the control group and model group were treated with normal saline (10 ml/kg), the prednisone group was treated with prednisone 4.5 mg/kg (10 ml/kg), and the low, middle, and high dose safflower groups were treated with safflower at the doses of 1.5, 3, 6 g/kg (10 ml/kg), and all groups were treated for 28 days.After 28 days, all mice were decapitated. The blood samples and back skin of the BLM injection part were collected.After that, all the tissue slices were taken to measure the dermal thickness, and the content of hydroxyproline (HYP) in the skin tissues was detected by hydrolysis method.The contents of tissue growth factor (CTGF) and transforming growth factor-ß (TGF-ß ) in the skin tissues and the levels of interleukin-6 (IL-6) and interleukin-17 (IL-17) in serum were determined by ELISA. RESULTS: Compared with the control group, the dermal thickness of the model group was increased(P＜0.05), the contents of CTGF, TGF-ß and HYP in the skin tissues and the levels of IL-6 and IL-17 in the serum of the model group were increased(P＜0.05); compared with the model group, the dermal thickness in the prednisone group and safflower groups was decreased (P＜0.05), the levels of CTGF, TGF-ß and HYP in the skin tissues and the serum levels of IL-6 and IL-17 in the prednisone group and safflower groups were decreased (P＜0.05). CONCLUSION: Safflower water extract can improve skin condition (or dermal thickness) in SSc mice, and its mechanism may be related to reducing immune inflammatory response.