Highlights d Heterogeneity and plasticity of non-parenchymal cells in healthy and NASH liver d Landscape of intrahepatic ligand-receptor signaling at single-cell resolution d Emergence of Trem2+ NASH-associated macrophages (NAMs) in mouse and human NASH d Stellakine secretion and contractile response to vasoactive hormones by HSCs

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Periodontitis is a prevalent chronic, destructive inflammatory disease affecting tooth-supporting tissues in humans. Guided tissue regeneration strategies are widely utilized for periodontal tissue regeneration generally by using a periodontal membrane. The main role of these membranes is to establish a mechanical barrier that prevents the apical migration of the gingival epithelium and hence allowing the growth of periodontal ligament and bone tissue to selectively repopulate the root surface. Currently available membranes have limited bioactivity and regeneration potential. To address such challenges, an osteoconductive, antibacterial, and flexible poly(caprolactone) (PCL) composite membrane containing zinc oxide (ZnO) nanoparticles is developed. The membranes are fabricated through electrospinning of PCL and ZnO particles. The physical properties, mechanical characteristics, and in vitro degradation of the engineered membrane are studied in detail. Also, the osteoconductivity and antibacterial properties of the developed membrane are analyzed in vitro. Moreover, the functionality of the membrane is evaluated with a rat periodontal defect model. The results confirmed that the engineered membrane exerts both osteoconductive and antibacterial properties, demonstrating its great potential for periodontal tissue engineering.

Cell-laden hydrogels are widely used in tissue engineering and regenerative medicine. However, many of these hydrogels are not optimized for use in the oral environment, where they are exposed to blood and saliva. To address these challenges, we engineered an alginate-based adhesive, photocrosslinkable, and osteoconductive hydrogel biomaterial (AdhHG) with tunable mechanical properties. The engineered hydrogel was used as an injectable mesenchymal stem cell (MSC) delivery vehicle for craniofacial bone tissue engineering applications. Subcutaneous implantation in mice confirmed the biodegradability, biocompatibility, and osteoconductivity of the hydrogel. In a well-established rat peri-implantitis model, application of the adhesive hydrogel encapsulating gingival mesenchymal stem cells (GMSCs) resulted in complete bone regeneration around ailing dental implants with peri-implant bone loss. Together, we have developed a distinct bioinspired adhesive hydrogel with tunable mechanical properties and biodegradability that effectively delivers patient-derived dental-derived MSCs. The hydrogel is photocrosslinkable and, due to the presence of MSC aggregates and hydroxyapatite microparticles, promotes bone regeneration for craniofacial tissue engineering applications.

Mesenchymal stem cells (MSCs) provide an advantageous alternative therapeutic option for bone regeneration in comparison to current treatment modalities. However, delivering MSCs to the defect site while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated bone regeneration. Here, we tested the bone regeneration capacity of periodontal ligament stem cells (PDLSCs) and gingival mesenchymal stem cells (GMSCs) encapsulated in a novel RGD-(arginine-glycine-aspartic acid tripeptide) coupled alginate microencapsulation system in vitro and in vivo. Five-millimeter-diameter critical-size calvarial defects were created in immunocompromised mice and PDLSCs and GMSCs encapsulated in RGD-modified alginate microspheres were transplanted into the defect sites. New bone formation was assessed using microcomputed tomography and histological analyses 8 weeks after transplantation. Results confirmed that our microencapsulation system significantly enhanced MSC viability and osteogenic differentiation in vitro compared with non-RGD-containing alginate hydrogel microspheres with larger diameters. Results confirmed that PDLSCs were able to repair the calvarial defects by promoting the formation of mineralized tissue, while GMSCs showed significantly lower osteogenic differentiation capability. Further, results revealed that RGD-coupled alginate scaffold facilitated the differentiation of oral MSCs toward an osteoblast lineage in vitro and in vivo, as assessed by expression of osteogenic markers Runx2, ALP, and osteocalcin. In conclusion, these results for the first time demonstrated that MSCs derived from orofacial tissue encapsulated in RGD-modified alginate scaffold show promise for craniofacial bone regeneration. This treatment modality has many potential dental and orthopedic applications.

The objectives of this study were to: (1) develop an injectable and biodegradable scaffold based on oxidized alginate microbeads encapsulating periodontal ligament (PDLSCs) and gingival mesenchymal stem cells (GMSCs); and (2) investigate the stem cell viability, and osteogenic differentiation of the stem cells in vitro. Stem cells were encapsulated using alginate hydrogel. The stem cell viability, proliferation and differentiation to adipogenic and osteogenic tissues were studied. To investigate the expression of both adipogenesis and ontogenesis related genes, the RNA was extracted and RT-PCR was performed. The degradation behavior of hydrogel based on oxidized sodium alginate with different degrees of oxidation was studied in PBS at 37 °C as a function of time by monitoring the changes in weight loss. The swelling kinetics of alginate hydrogel was also investigated. The results showed that alginate is a promising candidate as a non-toxic scaffold for PDLSCs and GMSCs. It also has the ability to direct the differentiation of these stem cells to osteogenic and adipogenic tissues as compared to the control group in vitro. The encapsulated stem cells remained viable in vitro and both osteo-differentiated and adipo-differentiated after 4 weeks of culturing in the induction media. It was found that the degradation profile and swelling kinetics of alginate hydrogel strongly depends on the degree of oxidation showing its tunable chemistry and degradation rate. These findings demonstrate for the first time that immobilization of PDLSCs and GMSCs in the alginate microspheres provides a promising strategy for bone tissue engineering.

Dental-derived mesenchymal stem cells (MSCs) provide an advantageous therapeutic option for tissue engineering due to their high accessibility and bioavailability. However, delivering MSCs to defect sites while maintaining a high MSC survival rate is still a critical challenge in MSC-mediated tissue regeneration. Here, we tested the osteogenic and adipogenic differentiation capacity of dental pulp stem cells (DPSCs) in a thermoreversible Pluronic F127 hydrogel scaffold encapsulation system in vitro. DPSCs were encapsulated in Pluronic® F-127 hydrogel and stem cell viability, proliferation and differentiation into adipogenic and osteogenic tissues were evaluated. The degradation profile and swelling kinetics of the hydrogel were also analyzed. Our results confirmed that Pluronic F-127 is a promising and non-toxic scaffold for encapsulation of DPSCs as well as control human bone marrow MSCs (hBMMSCs), yielding high stem cell viability and proliferation. Moreover, after 2 weeks of differentiation in vitro, DPSCs as well as hBMMSCs exhibited high levels of mRNA expression for osteogenic and adipogenic gene markers via PCR analysis. Our histochemical staining further confirmed the ability of Pluronic F-127 to direct the differentiation of these stem cells into osteogenic and adipogenic tissues. Furthermore, our results revealed that Pluronic F-127 has a dense tubular and reticular network morphology, which contributes to its high permeability and solubility, consistent with its high degradability in the tested conditions. Altogether, our findings demonstrate that Pluronic F-127 is a promising scaffold for encapsulation of DPSCs and can be considered for cell delivery purposes in tissue engineering.

Periodontitis is a common chronic inflammatory disease that affects tooth-supporting tissues. We engineer a multifunctional periodontal membrane for the guided tissue regeneration of lost periodontal tissues. The major drawback of current periodontal membranes is the lack of tissue regeneration properties. Here, a series of nanofibrous membranes based on poly­(ε-caprolactone) with tunable biochemical and biophysical properties were developed for periodontal tissue regeneration. The engineered membranes were surface coated using biomimetic polydopamine to promote the adhesion of therapeutic proteins and cells. We demonstrate successful cellular localization on the surface of the engineered membrane by morphological patterning. Polydopamine accelerates osteogenic differentiation of dental-derived stem cells by promoting hydroxyapatite mineralization. Such multiscale designs can mimic the complex extracellular environment of periodontal tissue and serve as functional tissue constructs for periodontal regeneration. In a periodontal defect model in rats, our engineered periodontal membrane successfully promoted the regeneration of periodontal tissue and bone repair. Altogether, our data demonstrate that our biomimetic membranes have potential as protein/cell delivery platforms for periodontal tissue engineering.