Antimicrobial Peptide- and Dentin Matrix-Functionalized Hydrogel for Vital Pulp Therapy via Synergistic Bacteriostasis, Immunomodulation, and Dentinogenesis.

The preservation of vital pulps is crucial for maintaining the physiological functions of teeth; however, vital pulp therapy (VPT) of pulpitis teeth remains a substantial challenge due to uncontrolled infection, excessive inflammation, and limited regenerative potential. Current pulp capping agents have restricted effects in the infectious and inflammatory microenvironment. To address this, a multifunctional hydrogel (TGH/DM) with antibacterial, immunomodulatory, and mineralization-promoting effects is designed. The antimicrobial peptide (AMP) and demineralized dentin matrix are incorporated into the hydrogel, achieving sustainable delivery of AMP and a cocktail of growth factors. In vitro results show that TGH/DM could kill endodontic microbiota, ameliorate inflammatory responses of human dental pulp stem cells (hDPSCs), and prompt odontogenic differentiation of inflammatory hDPSCs via activation of peroxisome proliferator-activated receptor gamma. In vivo results suggest that TGH/DM is capable of inducing M2 phenotype transformation of macrophages in mice and fostering the regeneration of the dentin-pulp complex in inflamed pulps of beagle dogs. Overall, this study first proposes the synergistic regulation of AMP and tissue-specific extracellular matrix for the treatment of pulpitis, and the advanced hydrogel provides a facile and effective way for VPT.

Mechanical Stimulation of Anti-Inflammatory and Antioxidant Hydrogels for Rapid Re-Epithelialization.

The epithelium, an essential barrier to protect organisms against infection, exists in many organs. However, rapid re-epithelialization to restore tissue integrity and function in an adverse environment is challenging. In this work, a long-term anti-inflammatory and antioxidant hydrogel with mechanical stimulation for rapid re-epithelialization, mainly composed of the small molecule thioctic acid, biocompatible glycine, and γ-Fe2O3 nanoparticles is reported. Glycine-modified supramolecular thioctic acid is stable and possesses outstanding mechanical properties. The incorporating γ-Fe2O3 providing the potential contrast function for magnetic resonance imaging observation, can propel hydrogel reconfiguration to enhance the mechanical properties of the hydrogel underwater due to water-initiated release of Fe3+. In vitro experiments show that the hydrogels effectively reduced intracellular reactive oxygen species, guided macrophages toward M2 polarization, and alleviated inflammation. The effect of rapid re-epithelialization is ultimately demonstrated in a long urethral injury model in vivo, and the mechanical stimulation of hydrogels achieves effective functional replacement and ultimately accurate remodeling of the epithelium. Notably, the proposed strategy provides an advanced alternative treatment for patients in need of large-area epithelial reconstruction.

A sandwiched patch toward leakage-free and anti-postoperative tissue adhesion sealing of intestinal injuries.

Ideal repair of intestinal injury requires a combination of leakage-free sealing and postoperative antiadhesion. However, neither conventional hand-sewn closures nor existing bioglues/patches can achieve such a combination. To this end, we develop a sandwiched patch composed of an inner adhesive and an outer antiadhesive layer that are topologically linked together through a reinforced interlayer. The inner adhesive layer tightly and instantly adheres to the wound sites via -NHS chemistry; the outer antiadhesive layer can inhibit cell and protein fouling based on the zwitterion structure; and the interlayer enhances the bulk resilience of the patch under excessive deformation. This complementary trilayer patch (TLP) possesses a unique combination of instant wet adhesion, high mechanical strength, and biological inertness. Both rat and pig models demonstrate that the sandwiched TLP can effectively seal intestinal injuries and inhibit undesired postoperative tissue adhesion. The study provides valuable insight into the design of multifunctional bioadhesives to enhance the treatment efficacy of intestinal injuries.

Functional reconstruction of injured corpus cavernosa using 3D-printed hydrogel scaffolds seeded with HIF-1α-expressing stem cells.

Injury of corpus cavernosa results in erectile dysfunction, but its treatment has been very difficult. Here we construct heparin-coated 3D-printed hydrogel scaffolds seeded with hypoxia inducible factor-1α (HIF-1α)-mutated muscle-derived stem cells (MDSCs) to develop bioengineered vascularized corpora. HIF-1α-mutated MDSCs significantly secrete various angiogenic factors in MDSCs regardless of hypoxia or normoxia. The biodegradable scaffolds, along with MDSCs, are implanted into corpus cavernosa defects in a rabbit model to show good histocompatibility with no immunological rejection, support vascularized tissue ingrowth, and promote neovascularisation to repair the defects. Evaluation of morphology, intracavernosal pressure, elasticity and shrinkage of repaired cavernous tissue prove that the bioengineered corpora scaffolds repair the defects and recover penile erectile and ejaculation function successfully. The function recovery restores the reproductive capability of the injured male rabbits. Our work demonstrates that the 3D-printed hydrogels with angiogenic cells hold great promise for penile reconstruction to restore reproductive capability of males.

Wet-adhesive, haemostatic and antimicrobial bilayered composite nanosheets for sealing and healing soft-tissue bleeding wounds.

Healing soft-tissue wounds with an irregular, complicated topography in a bleeding environment demands the development of a dressing that is wet-adhesive, haemostatic, and antibacterial. To meet this unmet demand, we designed a flexible nanosheet (~77 nm thick) made of two layers, one is the antibacterial and haemostatic gelatin modified with dopamine (DA) and antimicrobial peptide (AMP) and mixed with Ca2+ ions as coagulation factors, and another is the mechanically strong polycaprolactone (PCL). This flexible nanosheet exhibited robust mechanical strength, continuous and effective adhesion to a topographically irregular tissue surface under a wet condition, and a high platelet adhesion capacity. Moreover, the nanosheet presented a significantly reduced clotting time of 4 min and a high bactericidal rate of nearly 100%. An in vivo evaluation of the nanosheet using both murine dorsal skin and liver models further revealed that the nanosheet could successfully seal and heal the wounds in a bleeding environment, efficiently control haemorrhaging, and exert an excellent antibacterial effect in two weeks. Our work suggests that this nanosheet holds great promise in healing the bleeding soft-tissue wounds for treating acute trauma.

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.

Molecular recognition-directed site-specific release of stem cell differentiation inducers for enhanced joint repair.

The remarkable difference in cell type and matrix composition between two connected parts of a joint (cartilage and subchondral bone) makes it challenging to simultaneously regenerate both parts for joint repair. Thus we chemically designed a biphasic hydrogel made of two well-bonded shape-tunable hydrogel phases, termed bone-regenerating hydrogel (BRH) and cartilage-regenerating hydrogel (CRH). The BRH and CRH, encapsulating stem cells, were produced by photo-crosslinking bone and cartilage matrix-mimicking biopolymers and a nanobox (ß-cyclodextrin) in situ in the subchondral bone defect and cartilage defect, respectively. The nanoboxes in BRH and CRH were loaded with osteogenic and chondrogenic differentiation inducers (melatonin and kartogenin) by host-guest interactions, respectively. Such interactions directed the sustained phase- and defect site-specific release of the inducers and subsequent site-specific stem cell differentiation into cartilage and bone forming cells for joint repair. The strategy opens up a new chemical approach to biomaterials with phase-specific drug release for tissue repair.

Di-n-butyl phthalate exposure negatively influences structural and functional neuroplasticity via Rho-GTPase signaling pathways.

Di-n-butyl phthalate (DBP) has been reported to cause disruptions in hippocampal plasticity, but its specific mechanism has not yet been ascertained. In this research, a mouse model of chronic DBP exposure was generated by intragastric administration of DBP (10, 50, or 250°mg/kg/d) for 5 weeks. Chronic exposure to high concentrations of DBP (250°mg/kg/d) induced a spatial learning deficit in the Morris water maze in male mice. By determining the activity of Rho-GTPase signaling pathways in the hippocampal tissues, we found that DBP exposure inhibited the activity of Rac1/PAK1/LIMK1 but activated RhoA/ROCK/LIMK2 signaling and eventually suppressed cofilin activity by phosphorylation. Consistent with this, the differential activation was also observed in the acute exposure model of neuronal cells generated by incubation with DBP (100°ng/ml, 1, 10, or 100°µg/ml) for 72 hours. Moreover, acute exposure to high concentrations of DBP (100°µg/ml) altered cell morphology by inhibiting neurite outgrowth. A ROCK inhibitor, but not inhibitors of Rac1 or PAK1, reversed the inhibition of DBP to the activity of cofilin and neurite outgrowth in cells. These findings provide the first evidence that DBP exposure results in impairment of neuroplasticity by differential regulation of Rho-GTPase signaling pathways.