Gut Microbiota-Derived 3-Hydroxybutyrate Blocks GPR43-Mediated IL6 Signaling to Ameliorate Radiation Proctopathy.

Radiation proctopathy (RP) is a common complication of radiotherapy for pelvic malignancies with high incidence. RP accompanies by microbial dysbiosis. However, how the gut microbiota affects the disease remains unclear. Here, metabolomics reveals that the fecal and serous concentrations of microbiota-derived 3-hydroxybutyrate (3HB) are significantly reduced in RP mice and radiotherapeutic patients. Moreover, the concentration of 3HB is negatively associated with the expression of proinflammatory IL6 that is increased along with the severity of radiation damage. 3HB treatment significantly downregulates IL6 expression and alleviates IL6-mediated radiation damage. Irradiated cell-fecal microbiota co-culture experiments and in vivo assays show that such a radioprotection of 3HB is mediated by GPR43. Microbiome analysis reveals that radiation leads to a distinct bacterial community compared to untreated controls, in which Akkermansia muciniphila is significantly reduced in RP mice and radiotherapeutic patients and is associated with lower 3HB concentration. Gavage of A. muciniphila significantly increases 3HB concentration, downregulates GPR43 and IL6 expression, and ameliorates radiation damage. Collectively, these results demonstrate that the gut microbiota, including A. muciniphila, induce higher concentrations of 3HB to block GPR43-mediated IL6 signaling, thereby conferring radioprotection. The findings reveal a novel implication of the gut-immune axis in radiation pathophysiology, with potential therapeutic applications.

Peptide-AIE Nanofibers Functionalized Sutures with Antimicrobial Activity and Subcutaneous Traceability.

As one of the most widely used medical devices, sutures face challenges related to surgical site infections (SSIs) and lack of subcutaneous traceability. In the present study, a facile and effective approach using peptide-AIE nanofibers (NFs-K18) to create fluorescent-traceable antimicrobial sutures, which have been applied to four commercially available sutures is developed. The functionalized sutures of PGAS-NFs-K18 and PGLAS-NFs-K18 exhibit fluorescence with excellent penetration from 4 mm chicken breasts. They also demonstrate remarkable stability after 24 h of white light illumination and threading through chicken breasts 10 times. These sutures efficiently generate ROS, resulting in significant suppression of four clinical bacteria, with the highest antimicrobial rate of ≈100%. Moreover, the sutures exhibit favorable hemocompatibility and biocompatibility. In vivo experiments demonstrate that the optimized PGLAS-NFs-K18 suture displays potent antimicrobial activity against MRSA, effectively inhibiting inflammation and promoting tissue healing in both skin wound and abdominal wall wound models, outperforming the commercially available Coated VICRYL Plus Antibacterial suture. Importantly, PGLAS-NFs-K18 exhibits sensitive subcutaneous traceability, allowing for accurate in situ monitoring of its degradation. It is believed that this straightforward strategy offers a new pathway for inhibiting SSIs and monitoring the status of sutures.

Puerarin-Loaded Electrospun Patches with Anti-Inflammatory and Pro-Collagen Synthesis Properties for Pelvic Floor Reconstruction.

Pelvic organ prolapse (POP) is one of the most common pelvic floor dysfunction disorders worldwide. The weakening of pelvic connective tissues initiated by excessive collagen degradation is a leading cause of POP. However, the patches currently used in the clinic trigger an unfavorable inflammatory response, which often leads to implantation failure and the inability to simultaneously reverse progressive collagen degradation. Therefore, to overcome the present challenges, a new strategy is applied by introducing puerarin (Pue) into poly(l-lactic acid) (PLLA) using electrospinning technology. PLLA improves the mechanical properties of the patch, while Pue offers intrinsic anti-inflammatory and pro-collagen synthesis effects. The results show that Pue is released from PLLA@Pue in a sustained manner for more than 20 days, with a total release rate exceeding 80%. The PLLA@Pue electrospun patches also show good biocompatibility and low cytotoxicity. The excellent anti-inflammatory and pro-collagen synthesis properties of the PLLA@Pue patch are demonstrated both in vitro in H2O2-stimulated mouse fibroblasts and in vivo in rat abdominal wall muscle defects. Therefore, it is believed that this multifunctional electrospun patch integrating anti-inflammatory and pro-collagen synthesis properties can overcome the limitations of traditional patches and has great prospects for efficient pelvic floor reconstruction.

Nanoengineered Supramolecular Adhesive Sponge for Rapid Hemostasis and Abdominal Wall Wound Healing.

Multifunctional dressing biomaterials that can promote tissue adhesion, hemostasis, and soft-tissue wound healing are of great clinical significance. Here, we report a nanocomposite supramolecular sponge constructed by an air-in-water emulsion template composed of methacrylated gelatin (GelMA), Laponite nanoclay, and branched supramolecular polymer (PAMU). The sponge has an interconnected macroporous structure and exhibits tunable mechanical properties with varying Laponite concentration. The nanoengineered sponge is endowed with tissue adhesion by intermolecular hydrogen bonds and ionic interactions contributed by the supramolecular polymer and the Laponite nanoclay. The biocompatible sponge facilitates cell proliferation and blood coagulation in both in vitro and in vivo experiments. In addition, the results of the rat external abdominal wall defect model show that the sponge can promote angiogenesis, collagen deposition, and granulation tissue formation to accelerate wound repair. These findings suggest that the unique air-in-water templated sponge is a promising candidate for applications in hemostasis and wound healing.

Spatial Distribution Characteristics of Microbial Mineralization in Saturated Sand Centrifuge Shaking Table Test.

Calcium carbonate induced by microorganisms can quickly fill and cement sand particles, thereby effectively reducing the potential for the liquefaction of sand. This process could represent a new green approach to the liquefaction treatment of saturated sand and has good prospects for application. However, owing to the diversity of microbial activities and the heterogenous spatiotemporal distribution of bacterial nutrient seepage in sandy soil foundations, the resultant complex distribution of calcium carbonate deposition in a sandy soil foundation can lead to differences in solidification strength and improvement effect. To understand the influence of earthquake action on the liquefaction resistance of saturated sand treated by microorganisms, and to evaluate the effect of microbial technology on sand liquefaction prevention under dynamic load, this study simulated the dynamic stress conditions of saturated sand under shear waves, using the world's first centrifuge shaking table (R500B), which realizes horizontal and vertical two-way vibration. On the basis of spatial heterogeneity of microbial mineralization after centrifuge shaking table tests, the effect of microbial strengthening on liquefied sand was analyzed, and the spatial distribution of calcium carbonate mineralization was examined. The results showed that the distribution of microorganisms in the solidified soil exhibited obvious spatial heterogeneity with a significant edge effect. Although microbial mineralization effectively improved the liquefaction resistance of saturated sand, a sudden change in the process of calcium carbonate deposition altered the cementation of the sand with depth. Moreover, the curing strength had obvious complexity and uncertainty that directly affected the shear stiffness of the soil under dynamic load, and this constitutes one of the reasons for the degradation of shear stiffness of sand during liquefaction. The derived conclusions could be used as a reference for engineering applications of microbial treatment of a liquefiable sandy soil foundation.

Regulation of Myogenic Differentiation by Topologically Microgrooved Surfaces for Skeletal Muscle Tissue Engineering.

Inspired by the natural topological structure of skeletal muscle tissue, the topological surface construction of bionic scaffolds for skeletal muscle repair has attracted great interest. Many previous studies have focused on the effects of the topological structure on myoblasts. However, these studies used only specific repeating sizes and shapes to achieve the myoblast alignment and myotube formation; moreover, the regulatory effects of the size of a topological structure on myogenic differentiation are often neglected, leading to a lack of guidance for the design of scaffolds for skeletal muscle tissue engineering. In this study, we fabricated a series of microgroove topographies with various widths and depths via a combination of soft lithography and melt-casting and studied their effects on the behaviors of skeletal muscle cells, especially myogenic differentiation, in detail. Microgrooved poly(lactic-co-glycolic acid) substrates were found to effectively regulate the proliferation, myogenic differentiation, and myotube formation of C2C12 cells, and the degree of myogenic differentiation was significantly dependent on signals in response to the size of the microgroove structure. Compared with their depth, the width of the microgroove structures can more strongly affect the myogenic differentiation of C2C12 cells, and the degree of myoblast differentiation was enhanced with increasing groove width. Microgroove structures with relatively large groove widths and small groove depths promoted the myogenic differentiation of C2C12 cells. In addition, the integrin-mediated focal adhesion kinase signaling pathway and MAPK signaling pathway were activated in cells in response to the external topological structure, and the size of the topological structure of the material surface effectively regulated the degree of the cellular response to the external topological structure. These results can guide the design of scaffolds for skeletal muscle tissue engineering and the construction of effective bionic scaffold surfaces for skeletal muscle regeneration.

UV-curable hyperbranched polyester sealant with tunable mechanical properties.

Different types of wounds have different requirements of a wound sealant. One of the requirements of concern is the adaptability of the mechanical properties of biomaterials to native tissues. However, the mechanical properties of current sealant are untunable or adjustable in a small range normally. Therefore, the scope of application of these sealant is limited. In this study, we developed hyperbranched polyester (HBP)-based UV-curable sealant with tunable mechanical properties. This sealant was cured under UV-light for 2 minutes and exhibited strong adhesion with tissues. The shear adhesive strength of it to the porcine skin ranged between 20-30 kPa, which was higher than the fibrin glue (∼10 kPa). Moreover, the elastic modulus of the sealant in a tensile test ranged between 27-54 MPa, depending on the degree of acrylation of the HBPs. Additionally, we assessed the biocompatibility of the sealant by co-culturing it with mouse mesenchymal stem cells (mMSCs) for 7 days and discovered that the cell viability was unaffected. This sealant with a tunable elastic modulus might be a promising candidate for treating wounds with different elastic moduli.

Highly Stretchable, Adhesive, Biocompatible, and Antibacterial Hydrogel Dressings for Wound Healing.

Treatment of wounds in special areas is challenging due to inevitable movements and difficult fixation. Common cotton gauze suffers from incomplete joint surface coverage, confinement of joint movement, lack of antibacterial function, and frequent replacements. Hydrogels have been considered as good candidates for wound dressing because of their good flexibility and biocompatibility. Nevertheless, the adhesive, mechanical, and antibacterial properties of conventional hydrogels are not satisfactory. Herein, cationic polyelectrolyte brushes grafted from bacterial cellulose (BC) nanofibers are introduced into polydopamine/polyacrylamide hydrogels. The 1D polymer brushes have rigid BC backbones to enhance mechanical property of hydrogels, realizing high tensile strength (21-51 kPa), large tensile strain (899-1047%), and ideal compressive property. Positively charged quaternary ammonium groups of tethered polymer brushes provide long-lasting antibacterial property to hydrogels and promote crawling and proliferation of negatively charged epidermis cells. Moreover, the hydrogels are rich in catechol groups and capable of adhering to various surfaces, meeting adhesive demand of large movement for special areas. With the above merits, the hydrogels demonstrate less inflammatory response and faster healing speed for in vivo wound healing on rats. Therefore, the multifunctional hydrogels show stable covering, little displacement, long-lasting antibacteria, and fast wound healing, demonstrating promise in wound dressing.

Nomogram for Predicting Anastomotic Leakage after Rectal Cancer Surgery in Elderly Patients with Dysfunctional Stomata.

PURPOSE: Anastomotic leakage after rectal cancer surgery in elderly patients is a critical challenge. Many risk factors have been found and many interventions tried, but anastomotic leakage in elderly patients remains difficult to deal with. This study aimed to create a nomogram for predicting anastomotic leakage after rectal surgery in elderly rectal cancer patients with dysfunctional stomata. METHODS: We collected data from 326 consecutive elderly patients with dysfunctional stomata after rectal cancer surgery at the Sixth Affiliated Hospital, Sun Yat-Sen University from January 2014 to December 2019. Risk factors of anastomotic leakage were identified with multivariate logistic regression and used to create a nomogram. Predictive performance was evaluated by the area under the receiver-operating characteristic (ROC) curve. RESULTS: American Society of Anesthesiologists score ≥3, male sex, and neoadjuvant radiotherapy were identified as significantly associated factors that could be combined for accurate prediction of anastomotic leakage on multivariate logistic regression and development of a nomogram.The area under the ROC curve for this model was 0.645. The C-index value for this model was 0.645, indicating moderate predictive ability of the risk of anastomotic leakage. CONCLUSION: The nomogram showed good ability to predict anastomotic leakage in elderly patients with rectal cancer after surgery, and might be helpful in providing a reference point for selection of surgical procedures and perioperative treatment.

Core-Shell Poly(l-lactic acid)-Hyaluronic Acid Nanofibers for Cell Culture and Pelvic Ligament Tissue Engineering.

Pelvic organ prolapse (POP) has become one of the most common serious diseases affecting parous women. Weakening of pelvic ligaments plays an essential role in the pathophysiology of POP. Currently, synthetic materials are widely applied for pelvic reconstructive surgery. However, synthetic nondegradable meshes for POP therapy cannot meet the clinical requirements due to its poor biocompatibility. Herein, we fabricated electrospun core-shell nanofibers of poly(l-lactic acid)-hyaluronic acid (PLLA/HA). After that, we combined them with mouse bone marrow-derived mesenchymal stem cells (mBMSCs) to assess the cellular response and pelvic ligament tissue engineering in vitro. The cellular responses on the composite nanofibers showed that the core-shell structure nanofibers displayed with excellent biocompatibility and enhanced cellular activity without cytotoxicity. Moreover, compared with PLLA nanofibers seeded with mBMSCs, PLLA/HA nanofibers exhibited more cellular function, as revealed by the quantitative real-time polymerase chain reaction (RT-qPCR) for pelvic ligament-related gene markers including Col1a1, Col1a3 and Tnc. These features suggested that this novel core-shell nanofiber is promising in stem cell-based tissue engineering for pelvic reconstruction.

Fabrication and Characterization of the Core-Shell Structure of Poly(3-Hydroxybutyrate-4-Hydroxybutyrate) Nanofiber Scaffolds.

Tissue engineering scaffolds with nanofibrous structures provide positive support for cell proliferation and differentiation in biomedical fields. These scaffolds are widely used for defective tissue repair and drug delivery. However, the degradation performance and mechanical properties of scaffolds are often unsatisfactory. Here, we successfully prepared a novel poly(3-hydroxybutyrate-4-hydroxybutyrate)/polypyrrole (P34HB-PPy) core-shell nanofiber structure scaffold with electrospinning and in situ surface polymerization technology. The obtained composite scaffold showed good mechanical properties, hydrophilicity, and thermal stability based on the universal material testing machine, contact angle measuring system, thermogravimetric analyzer, and other methods. The results of the in vitro bone marrow-derived mesenchymal stem cells (BMSCs) culture showed that the P34HB-PPy composite scaffold effectively mimicked the extracellular matrix (ECM) and exhibited good cell retention and proliferative capacity. More importantly, P34HB is a controllable degradable polyester material, and its degradation product 3-hydroxybutyric acid (3-HB) is an energy metabolite that can promote cell growth and proliferation. These results strongly support the application potential of P34HB-PPy composite scaffolds in biomedical fields, such as tissue engineering and soft tissue repair.

Manipulating Mesenchymal Stem Cell Differentiation on Nanopattern Constructed through Cell-Mediated Mineralization.

The extracellular matrix microenvironment, including chemical constituents and topological structure, plays key role in regulating the cell behavior, such as adhesion, proliferation, differentiation, apoptosis, etc. Until now, to investigate the relationship between surface texture and cell response, various ordered patterns have been prepared on the surface of different matrixes, whereas almost all these strategies depend on advanced instruments or severe synthesis conditions. Herein, cell-mediated mineralization method has been applied to construct nanopattern on the surface of ß-TCP scaffold. The formation process, morphology, and composition of the final pattern were characterized, and a possible mineralization mechanism has been proposed. Moreover, the cell behavior on the nanopattern has been investigated, and the results showed that the mouse bone marrow mesenchyme stem cells (mBMSCs) display good affinity with the nanopattern, which was manifested by the good proliferation and osteogenic differentiation status of cells. The synthetic strategy may shed light to construct advanced topological structures on other matrixes for bone repair.

Constructing a Sr2+-Substituted Surface Hydroxyapatite Hexagon-Like Microarray on 3D-Plotted Hydroxyapatite Scaffold to Regulate Osteogenic Differentiation.

Surface topography and chemical characteristics can regulate stem cell proliferation and differentiation, and decrease the bone-healing time. However, the synergetic function of the surface structure and chemical cues in bone-regeneration repair was rarely studied. Herein, a strontium ion (Sr2+)-substituted surface hydroxyapatite (HA) hexagon-like microarray was successfully constructed on 3D-plotted HA porous scaffold through hydrothermal reaction to generate topography and chemical dual cues. The crystal phase of the Sr2+-substituted surface microarray was HA, while the lattice constant of the Sr2+-substituted microarray increased with increasing Sr2+-substituted amount. Sr2+-substituted microarray could achieve the sustainable release of Sr2+, which could effectively promote osteogenic differentiation of human adipose-derived stem cells (ADSCs) even without osteogenic-induced media. Osteogenic characteristics were optimally enhanced using the higher Sr2+-substituted surface microarray (8Sr-HA). Sr2+-substituted microarray on the scaffold surface could future improve the osteogenic performance of HA porous scaffold. These results indicated that the Sr2+-substituted HA surface hexagon-like microarray on 3D-plotted HA scaffolds had promising biological performance for bone-regeneration repair scaffold.

RNA-binding protein CELF1 enhances cell migration, invasion, and chemoresistance by targeting ETS2 in colorectal cancer.

Colorectal cancer (CRC) is often diagnosed at later stages after it has metastasized to other organs. The development of chemoresistance also contributes to a poor prognosis. Therefore, an increased understanding of the metastatic properties of CRC and chemoresistance could improve patient survival. CUGBP elav-like family member 1 (CELF1) is an RNA-binding protein, which is overexpressed in many human malignant tumors. However, the influence of CELF1 in CRC is unclear. V-ets erythroblastosis virus E26 oncogene homologue 2 (ETS2) is an evolutionarily conserved proto-oncogene known to be overexpressed in a variety of human cancers including CRC. In thespresent tudy, we investigated the association between CELF1 and ETS2 in CRC tumorigenesis and oxaliplatin (L-OHP) resistance. We found a positive correlation between the elevated expression of CELF1 and ETS2 in human CRC tissues. Overexpression of CELF1 increased CRC cell proliferation, migration, and invasion in vitro and in a xenograft tumor growth model in vivo, and induced resistance to L-OHP. In contrast, CELF1 knockdown improved the response of CRC cells to L-OHP. Overexpression of ETS2 increased the malignant behavior of CRC cells (growth, migration, and invasion) and L-OHP resistance in vitro. Moreover, L-OHP resistance induced by CELF1 overexpression was reversed by ETS2 knockdown. The results of luciferase reporter and ribonucleoprotein immunoprecipitation assays indicated that CELF1 up-regulates ETS2 by binding to its 3'-UTR. Taken together, our findings have identified that CELF1 regulates ETS2 in a mechanism that results in CRC tumorigenesis and L-OHP resistance, and CELF1 may be a promising target for overcoming chemoresistance in CRC.

Radical excision versus local resection for primary rectal gastrointestinal stromal tumors. Cohort Study.

BACKGROUND: Rectal gastrointestinal stromal tumor (GIST) is a rare digestive disease that originates in mesenchymal tissues and has malignant tendencies. At present, no standard treatment has been developed, and surgical approaches and the resection scope for rectal GISTs are controversial. METHODS: The clinical, surgical, pathological and prognosis data of patients with primary rectal GIST in our center from January 2008 to January 2019 were retrospectively collected. The patients were divided into the radical excision (RE) and local resection (LR) groups. RESULTS: A total of 537 GIST cases were collected, and 64 patients with primary rectal GIST were included in this study, including 25 cases in the RE group and 39 cases in the LR group. Tumor size (p = 0.013), distance from the anus (p = 0.038), National Institutes of Health (NIH) criteria (p = 0.001), preoperative adjuvant therapy (p = 0.016), postoperative adjuvant therapy (p = 0.028), blood loss (p = 0.048), operative time (p = 0.020) and the duration of hospitalization (p = 0.021) were statistically different between these 2 groups. The mean overall follow-up time was 46 months (range, 1-122 months). Disease recurrence was observed in 12 patients. No statistical differences were observed in 5-year disease-free survival (DFS) (93.3% vs 92.6%, p = 0.952) or overall survival (OS) (90.0% vs 91.6%, p = 0.832) between the RE group and the LR group. CONCLUSION: Our study showed that LR has a similar prognosis to that of RE with respect to DFS and OS. For appropriate cases, LR has the advantages of a short operative time, less bleeding, and a quick recovery. Especially when combined with neoadjuvant therapy, LR can also achieve better perioperative efficacy. Therefore, LR is an effective method for resection of rectal GISTs and warrants clinical endorsement.

A Biomimetic Biphasic Osteochondral Scaffold with Layer-Specific Release of Stem Cell Differentiation Inducers for the Reconstruction of Osteochondral Defects.

There is a great challenge in regenerating osteochondral defects because they involve lesions of both cartilage and subchondral bone, which have remarkable differences in their chemical compositions and biological lineages. Thus, considering the complicated requirements in osteochondral reconstruction, a biomimetic biphasic osteochondral scaffold (BBOS) with the layer-specific release of stem cell differentiation inducers are developed. The cartilage regeneration layer (cartilage scaffold, CS) in the BBOS contains a hyaluronic acid hydrogel to mimic the composition of cartilage, which is mechanically enhanced by host-guest supramolecular units to control the release of kartogenin (KGN). Additionally, a 3D-printed hydroxyapatite (HAp) scaffold releasing alendronate (ALN) is employed as the bone-regeneration layer (bone scaffold, BS). The two layers are bound by semi-immersion and could regulate the hierarchical targeted differentiation behavior of the stem cells. Compared to the drug-free scaffold, the MSCs in the BBOS could be promoted to differentiate into both chondrocytes and osteoblasts. The in vivo results demonstrate the strong promotion of cartilage or bone regeneration in their respective layers. It is expected that this BBOS with layer-specific inducer release can become a new strategy for osteochondral regeneration.

In Situ Formation of Hexagon-like Column Array Hydroxyapatite on 3D-Plotted Hydroxyapatite Scaffolds by Hydrothermal Method and Its Effect on Osteogenic Differentiation.

In the preparation of bioactive bone graft materials, surface topography is essential for the ultimate stem cell response. However, the tunable fabrication of surface topography for 3D bioceramic scaffolds is still a technical problem because of the low processability and high brittleness of bioceramics. In this study, an evenly spaced hexagon-like column array surface was fabricated in situ via a hydrothermal method on 3D plotted hydroxyapatite scaffolds. Compared with the Control scaffolds, hydroxyapatite scaffolds with a hexagon-like column array topography possessed a higher crystal orientation degree and specific surface area, which further enhanced fibronectin adsorption. The array topography on the hydroxyapatite scaffolds also showed good biocompatibility with human adipose-derived stem cells (ADSCs). More importantly, the Array scaffolds significantly promoted the expression levels of osteogenic-related genes and proteins compared with the Control scaffolds. The results suggested that the construction of hexagon-like column array topography might be critical for the design of bone regeneration scaffolds with spontaneous stimulation capacity.

MXene Composite Nanofibers for Cell Culture and Tissue Engineering.

MXenes are very promising emerging materials for diverse applications because of their outstanding properties. However, the effect of MXene on cell growth and differentiation had barely been studied. Here, we fabricated titanium carbide (Ti3C2) MXene composite nanofibers as smart biomaterials for cell culture and tissue engineering. The composite nanofibers were fabricated by electrospinning and doping and displayed excellent hydrophilicity because of a large number of introduced functional hydrophilic groups. The nanosurface and functional groups of MXene composite nanofibers provide a good microenvironment for cellular growth. Bone marrow-derived mesenchymal stem cells (BMSCs) were applied to assess their biochemical properties. The cell test outcome demonstrated that the obtained MXene composite nanofibers had good biocompatibility and greatly improved cellular activity. These composite nanofibers enhanced BMSC's differentiation to osteoblasts. The excellent biocompatibility combined with the nanoeffect of MXene suggested that this novel class of biomaterials has the potential to bridge the translational gap in materials sciences and stem cell-based tissue therapies and future multitask biomedical therapies based on MXene's unique advantages.

Substrate stiffness affects the immunosuppressive and trophic function of hMSCs via modulating cytoskeletal polymerization and tension.

Mesenchymal stem cells (MSCs) have broad therapeutic potential due to their ability to secrete bioactive factors that are immunomodulatory and trophic (regenerative). In this study, polyacrylamide (PAAm) hydrogels with different stiffness are used as a model to explore the effects of substrate stiffness on the paracrine function of human mesenchymal stem cells (hMSCs). Human MSCs cultured on soft substrates produced significantly higher levels of immunomodulatory and trophic factors compared with hMSCs cultured on rigid substrates. The enhanced paracrine function of hMSCs is further confirmed by the M2 phenotypic polarization observed in macrophages, as well as the accelerated chemotactic migration and angiogenesis capacity observed in human umbilical vein endothelial cells (HUVECs) after treatment with conditioned media (CM) collected from hMSCs cultured on soft substrates. Furthermore, the inhibited secretion of immunosuppressive and trophic factors by hMSCs cultured on rigid substrates is largely rescued by treatment with Lat.A, a cytoskeletal polymerization inhibitor. Similar results are observed after treatment with either myosin (Blebbi) or ROCK (Y27632) inhibitors. These results demonstrate that substrate stiffness is a key modulator of the paracrine function of hMSCs and highlight the potential utility of promoting tissue repair through stiffness-regulated paracrine signaling in MSCs.