An enzyme-responsive hydrogel of ferrocene-grafted carboxymethyl chitosan as a soft electrochemical sensor for MMP-9 detection.

Matrix metalloproteinase 9 (MMP-9) plays an important role in wound healing. However, overexpression of MMP-9 leads to the degradation of the newly formed extracellular matrix, which delays wound healing, ultimately leading to chronic wounds. Therefore, timely monitoring of the MMP-9 activity using simple, cost-effective methods is important to prevent the formation of chronic wounds. In this work, ferrocene-modified MMP-9 cleavage peptide (Fc-MG) modified carboxymethyl chitosan hydrogels were prepared as electrochemical biosensors. In the presence of MMP-9, the peptide chain is sheared, and the electrochemically active ferrocene segment is released. Therefore, analyzing the electrochemical activity of hydrogels using differential pulse voltammetry (DPV) can be used to determine MMP-9 activity. The results showed that the DPV peaks were correlated with the MMP-9 concentration in phosphate-buffered saline (PBS, pH 7.4) and Dulbecco's modified Eagle's medium (DMEM). Specifically, the corresponding coefficient of determination (R2) were 0.918 and 0.993. The limit of detections were 73.08 ng/mL and 131.71 ng/mL, respectively. Compared with the enzyme-linked immunosorbent assay, the hydrogel biosensor determined the concentration of MMP-9 in solution with simpler steps. This study demonstrates a novel strategy based on Fc-MG-modified hydrogels to monitor MMP-9 activity in cell secretion samples and shows the potential application in chronic wounds.

Minimally invasive delivery of human umbilical cord-derived mesenchymal stem cells by an injectable hydrogel via Diels-Alder click reaction for the treatment of intrauterine adhesions.

Intrauterine adhesions (IUA) are the most common cause of uterine infertility, and conventional treatments have not consistently achieved satisfactory pregnancy rates. Stem cell therapy shows promising potential for the clinical treatment of IUA. Although various advanced biomaterials have been designed for delivering stem cells to the uterine cavity, there remain significant challenges, particularly in devising therapeutic strategies for clinical application that minimize surgical incisions and conform to the intricate structure of uterine cavity. Herein, an injectable hydrogel loaded with human umbilical cord-derived mesenchymal stem cells (UCMSCs) was synthesized via the Diels-Alder click reaction for endometrial regeneration and fertility restoration, exhibiting suitable mechanical properties, good biocompatibility, and desirable degradation properties. Notably, this hydrogel permitted minimally invasive administration and integrated seamlessly with surrounding tissue. Our study revealed that the UCMSCs-laden injectable hydrogel enhanced cell proliferation, migration, angiogenesis, and exhibited anti-fibrotic effects in vitro. The implantation of this hydrogel significantly facilitated endometrium regeneration and restored fertility in a rat endometrial damage model. Mechanistically, in vivo results indicated that the UCMSCs-laden injectable hydrogel effectively promoted macrophage recruitment and facilitated M2 phenotype polarization. Collectively, this hydrogel demonstrated efficacy in regenerating damaged endometrium, leading to the restoration of fertility. Consequently, it holds promise as a potential therapeutic strategy for endometrial damage and fertility decline arising from intrauterine adhesions. STATEMENT OF SIGNIFICANCE: Severe endometrial traumas frequently lead to intrauterine adhesions and subsequent infertility. Stem cell therapy shows promising potential for the clinical treatment of IUA; however, challenges remain, including low delivery efficiency and compromised stem cell activity during the delivery process. In this study, we fabricated an injectable hydrogel loaded with UCMSCs via the Diels-Alder click reaction, which exhibited unique bioorthogonality. The in situ-gelling hydrogels could be introduced through a minimally invasive procedure and adapt to the intricate anatomy of the uterus. The UCMSCs-laden injectable hydrogel promoted endometrial regeneration and fertility restoration in a rat endometrial damage model, efficaciously augmenting macrophage recruitment and promoting their polarization to the M2 phenotype. The administration of UCMSCs-laden injectable hydrogel presents a promising therapeutic strategy for patients with severe intrauterine adhesion.

A construct of adipose-derived mesenchymal stem cells-laden collagen scaffold for fertility restoration by inhibiting fibrosis in a rat model of endometrial injury.

Severe endometrium damage causes pathological conditions such as thin endometrium and intrauterine adhesion, resulting in uterine factor infertility. Mesenchymal stem cell (MSC) therapy is a promising strategy in endometrial repair; yet, exogenous MSCs still raise concerns for safety and ethical issues. Human adipose-derived mesenchymal stem cells (ADMSCs) residing in adipose tissue have high translational potentials due to their autologous origin. To harness the high translation potentials of ADMSC in clinical endometrium regeneration, here we constructed an ADMSCs composited porous scaffold (CS/ADMSC) and evaluated its effectiveness on endometrial regeneration in a rat endometrium-injury model. We found that CS/ADMSC intrauterine implantation (i) promoted endometrial thickness and gland number, (ii) enhanced tissue angiogenesis, (iii) reduced fibrosis and (iv) restored fertility. We ascertained the pro-proliferation, pro-angiogenesis, immunomodulating and anti-fibrotic effects of CS/ADMSC in vitro and revealed that the CS/ADMSC influenced extracellular matrix composition and organization by a transcriptomic analysis. Our results demonstrated the effectiveness of CS/ADMSC for endometrial regeneration and provided solid proof for our future clinical study.

Inflammatory environment-adaptive patterned surface for spatiotemporal immunomodulation of macrophages.

Designing biomaterials with precise immunomodulation can help to decipher the dynamic interactions between macrophages and biomaterials to match the tissue healing process. Although some advanced stimuli-responsive immunomodulatory biomaterials were reported for cell dynamic modulation, while most triggers need external stimuli by manual intervention, there would be the inevitable errors and uncertainties. Thus, developing immunomodulatory biomaterials with adaptive abilities, which can recognize the inflammation signals, change their properties spatiotemporally under the microenvironment triggers, and provide feedback to realize macrophages modulation in different healing stages, has become a promising strategy. In this work, we developed an inflammation-adaptive Arg-Gly-Asp (RGD) -patterned surface for spatiotemporal immunomodulation of macrophage. We fabricated a methacrylated hyaluronic acid (MA-HA) hydrogel with thiol-functionalized RGD-patterned surface by employing photolithography technology. Then, thiol-functionalized RGD contained ROS-cleavable linker was filled the remaining sites and consequently, a dynamic surface with temporary homogeneous RGD was obtained. Under the overproduction of ROS by the inflammation-activated macrophages, the linker was cleaved, and the homogeneous RGD surface was transformed to the RGD patterned surface, which triggered elongation of macrophages and consequently the upregulated expressions of arginase-1, IL-10 and TNF-ß1, indicating the polarization toward to anti-inflammatory phenotype. Developing inflammatory environment-adaptive surface for spatiotemporal modulation of macrophages polarization provides a precise and smart strategy for the healing-matched immunomodulation to facilitate healing outcomes. STATEMENT OF SIGNIFICANCE: Designing biomaterials with precise immunomodulation can help to decipher the dynamic interactions between macrophages and biomaterials to match tissue repair process. Some immunomodulatory biomaterials were reported for cell dynamic modulation, while most triggers need external manual intervention. Thus, we developed an immunomodulatory biomaterial with inflammation-adaptive patterned surface, which can recognize abnormal signals and change its properties spatiotemporally under the microenvironment triggers, and provide feedback to realize macrophages modulation in different stages. The dynamic surface can adapt to the changes of microenvironment and dynamically to match the cell behavior and tissue healing process on demand without external manual intervention. Additionally, the surface achieves the balance of macrophages with pro- and anti-inflammatory phenotypes in the tissue repair process.

An Acellular Scaffold Facilitates Endometrial Regeneration and Fertility Restoration via Recruiting Endogenous Mesenchymal Stem Cells.

Severe intrauterine adhesions (IUAs), characterized by inadequate endometrial repair and fibrosis, can lead to infertility. Stem cell-based therapies, which deliver mesenchymal stem cells (MSCs) to the wound site, hold a considerable promise for endometrium regeneration. However, some notable hurdles, such as stemness loss, immunogenicity, low retention and survival rate, limit their clinical application. Evidence shows a strategy of mobilizing endogenous MSCs recruitment can overcome the traditional limitations of exogenous stem cell-based therapies. Here, an acellular biomaterial named stromal derived factor-1 alpha (SDF-1α)/E7-modified collagen scaffold (CES) is explored. CES based on harnessing the innate regenerative potential of the body enables near-complete endometrium regeneration and fertility restoration both in a rat endometrium acute damage model and a rat IUA model. Mechanistically, the CES implantation promotes endogenous MSCs recruitment via a macrophage-coordinated strategy; then the homing MSCs exert the function of immunomodulation and altered local microenvironments toward regeneration. To conclude, CES, which can harness endogenous MSCs and overcome the traditional limitations of cell-based therapies, can serve as a clinically feasible and cell-free strategy with high therapeutic efficiency for IUA treatment.