Osteogenic differentiation of adipose tissue-derived mesenchymal stem cells on fibrin glue- or fibronectin-coated Ceraform®

Fibronectin Functionalization: A Way to Enhance Dynamic Cell Culture on Alginate/Hydroxyapatite Scaffolds

Bone defects are a global health concern; bone tissue engineering (BTE) is the most promising alternative to reduce patient morbidity and overcome the inherent drawbacks of autograft and allograft bone. Three-dimensional scaffolds are pivotal in this field due to their potential to provide structural support and mimic the natural bone microenvironment. Following an already published protocol, a 3D porous structure consisting of alginate and hydroxyapatite was prepared after a gelation step and a freezing-drying step. Despite the frequent use of alginate in tissue regeneration, the biological inertness of this polysaccharide hampers proper cell colonization and proliferation. Therefore, the purpose of this work was to enhance the biological properties by promoting the interaction and adhesion between cells and biomaterial with the use of Fibronectin. This extracellular matrix protein was physically adsorbed on the scaffold, and its presence was evaluated with environmental scanning electron microscopy (eSEM) and the Micro-Bicinchoninic Acid (μBCA) protein assay. The MG-63 cell line was used for both static and dynamic (i.e., in bioreactor) 3D cell culturing on the scaffolds. The use of the bioreactor allowed for a better exchange of nutrients and oxygen and a better removal of cell catabolites from the inner portion of the construct, mimicking the physiological environment. The functionalized scaffolds showed an improvement in cell proliferation and colonization compared to non-functionalized ones; the effect of the addition of Fibronectin was more evident in the dynamic culturing conditions, where the cells clearly adhered on the surface of functionalized scaffolds.

Biocompatibility and interaction of porous alumina-zirconia scaffolds with adipose-derived mesenchymal stem cells for bone tissue regeneration

Replacement of bone defects with bone graft or implant is an important therapeutic strategy that has been used in routine practice. However, the identification of biomaterials that can mimic natural bone properties and serve as bone substitutes remains a major challenge. In this context, alumina-zirconia (Al2O3/ZrO2) nanocomposites emerge as potential alternatives for biomedical applications, owing to their high mechanical strength, wear resistance, and biocompatibility. In this sense, in this study, we prepared porous Al2O3/ZrO2 nanocomposites (scaffolds) using the gelcasting method and biomimetically coated them with calcium phosphate (CaP). We evaluated the biocompatibility of the scaffolds using the quantitative MTT cytotoxicity test in L929 cells. Moreover, rabbit adipose-derived mesenchymal stem cells (rADMSCs) were seeded with CaP-containing and CaP-free porous samples to evaluate cell proliferation and cell-scaffold interaction in vitro. Our results showed that the Al2O3/ZrO2 scaffolds were non-cytotoxic, and there were no significant differences between CaP-containing and CaP-free scaffolds in terms of cell growth and adhesion. In contrast, when co-cultured with rADMSCs, the scaffolds enhanced cell proliferation and cell adhesion. The rADMSCs adhered and migrated through the pores of the scaffold and anchored to different poles with differentiated elongated structures. These results suggest osteogenic differentiation of rADMSCs in response to mechanical loading of Al2O3/ZrO2 scaffolds. Therefore, we conclude that Al2O3/ZrO2 scaffolds have demonstrated significant implications in bone tissue engineering and are valuable biomaterials for bone replacement.

Up-to-date meta-analysis of long-term evaluations of mesenchymal stem cell therapy for complex perianal fistula

BACKGROUND

Local mesenchymal stem cell (MSC) therapy for complex perianal fistulas (PFs) has shown considerable promise. But, the long-term safety and efficacy of MSC therapy in complex PFs remain unknown.

AIM

To explore the long-term effectiveness and safety of local MSC therapy for complex PFs.

METHODS

Sources included the PubMed, EMBASE, and Cochrane Library databases. A standard meta-analysis was performed using RevMan 5.3.

RESULTS

After screening, 6 studies met the inclusion criteria. MSC therapy was associated with an improved long-term healing rate (HR) compared with the control condition [odds ratio (OR) = 2.13; 95% confidence interval (95%CI): 1.34 to 3.38; P = 0.001]. Compared with fibrin glue (FG) therapy alone, MSC plus FG therapy was associated with an improved long-term HR (OR = 2.30; 95%CI: 1.21 to 4.36; P = 0.01). When magnetic resonance imaging was used to evaluate fistula healing, MSC therapy was found to achieve a higher long-term HR than the control treatment (OR = 2.79; 95%CI: 1.37 to 5.67; P = 0.005). There were no significant differences in long-term safety (OR = 0.77; 95%CI: 0.27 to 2.24; P = 0.64).

CONCLUSION

Our study indicated that local MSC therapy promotes long-term and sustained healing of complex PFs and that this method is safe.

Plasma fibrin membranes loaded with bone marrow mesenchymal stem cells and corneal epithelial cells promote corneal injury healing via attenuating inflammation and fibrosis after corneal burns

The shortage of corneal donors has prompted the development of tissue-engineered corneal grafts as an alternative solution. Currently, amniotic membranes with good biocompatibility are widely used as scaffolds for loading stem cells in the treatment of corneal injury. However, this approach has its limitations. In this study, BMSCs were induced to differentiate into corneal epithelial cells via direct contact co-culture, and platelet-poor plasma was used to prepare fibrin gels, which were compressed to remove excess liquid and then lyophilized to obtain plasma fibrin membranes (PFMs). A tissue-engineered corneal implant with PFMs as a scaffold loaded with BMSCs and corneal epithelial cells was designed and obtained. Scanning electron microscopy showed that PFMs have a uniformly distributed microporous surface that facilitates cell attachment and nutrient transport. The rheological results showed that the freeze-dried and rehydrated PFMs were more rigid than fresh membranes, which makes it easier to use them for transplantation after cell loading. The experimental results of a rat alkali burn cornea injury model showed that PFMs effectively reduced the inflammatory reaction, inhibited fibrosis, and accelerated the healing of corneal wounds. It was also found that some of the BMSCs were successfully implanted into the corneal injury site in rats and differentiated into corneal epithelial cells. These results demonstrate the potential of tissue-engineered corneal implants using BMSCs and corneal epithelial cells and PFMs as scaffolds as a new treatment option for corneal injury.

Effects of Therapy with Fibrin Glue combined with Mesenchymal Stem Cells (MSCs) on Bone Regeneration: A Systematic Review

Cell therapy strategies using mesenchymal stem cells (MSCs) carried in fibrin glue have shown promising results in regenerative medicine. MSCs are crucial for tissue healing because they have angiogenic, anti-apoptotic and immunomodulatory properties, in addition to the ability to differentiate into several specialized cell lines. Fibrin sealant or fibrin glue is a natural polymer involved in the coagulation process. Fibrin glue provides a temporary structure that favors angiogenesis, extracellular matrix deposition and cell-matrix interactions. Additionally, fibrin glue maintains the local and paracrine functions of MSCs, providing tissue regeneration through less invasive clinical procedures. Thus, the objective of this systematic review was to assess the potential of fibrin glue combined with MSCs in bone or cartilage regeneration. The bibliographic search was performed in the PubMed/MEDLINE, LILACS and Embase databases, using the descriptors (“fibrin sealant” OR “fibrin glue”) AND “stem cells” AND “bone regeneration”, considering articles published until 2021. In this case, 12 preclinical and five clinical studies were selected to compose this review, according to the eligibility criteria. In preclinical studies, fibrin glue loaded with MSCs, alone or associated with bone substitute, significantly favored bone defects regeneration compared to scaffold without cells. Similarly, fibrin glue loaded with MSCs presented considerable potential to regenerate joint cartilage injuries and multiple bone fractures, with significant improvement in clinical parameters and absence of postoperative complications. Therefore, there is clear evidence in the literature that fibrin glue loaded with MSCs, alone or combined with bone substitute, is a promising strategy for treating lesions in bone or cartilaginous tissue.

Hydrogel mechanics are a key driver of bone formation by mesenchymal stromal cell spheroids

Mesenchymal stromal cells (MSCs) can promote tissue repair in regenerative medicine, and their therapeutic potential is further enhanced via spheroid formation. Stress relaxation of hydrogels has emerged as a potent stimulus to enhance MSC spreading and osteogenic differentiation, but the effect of hydrogel viscoelasticity on MSC spheroids has not been reported. Herein, we describe a materials-based approach to augment the osteogenic potential of entrapped MSC spheroids by leveraging the mechanical properties of alginate hydrogels. Compared to spheroids entrapped in covalently crosslinked elastic alginate, calcium deposition of MSC spheroids was consistently increased in ionically crosslinked, viscoelastic hydrogels. We previously demonstrated that intraspheroidal presentation of Bone Morphogenetic Protein-2 (BMP-2) on hydroxyapatite (HA) nanoparticles resulted in more spatially uniform MSC osteodifferentiation, providing a method to internally influence spheroid phenotype. In these studies, we observed significant increases in calcium deposition by MSC spheroids loaded with BMP-2-HA in viscoelastic gels compared to soluble BMP-2, which was greater than spheroids entrapped in all elastic alginate gels. Upon implantation in critically sized calvarial bone defects, bone formation was greater in all animals treated with viscoelastic hydrogels. Increases in bone formation were evident in viscoelastic gels, regardless of the mode of presentation of BMP-2 (i.e., soluble delivery or HA nanoparticles). These studies demonstrate that the dynamic mechanical properties of viscoelastic alginate are an effective strategy to enhance the therapeutic potential of MSC spheroids for bone formation and repair.

Synthesis and characterization of multifunctional organic-inorganic composite hydrogel formed with tissue-adhesive property and inhibiting infection

Organic-inorganic composite hydrogel materials have been widely studied. In order to expand the application of organic-inorganic composite hydrogel materials, in this work, we prepared a viscous hydrogel with antibacterial properties (OSA-GelDA@ACP/DA/Ag). First, we used polydopamine coating to deposit elemental silver on the surface of amorphous calcium phosphate (ACP) particles to prepare ACP/DA/Ag particles. Next, dopamine was grafted on the gelatin molecular chain by EDC/NHS to activate the carboxyl group to obtain dopamine-modified gelatin (GelDA). The content of DA in GelDA is about 14.09% by standard curve method. Then, the Schiff base reaction took place between the amino group on the GelDA molecular chain and the aldehyde group on the OSA molecular chain, and an OSA-GelDA viscous hydrogel was prepared. Finally, by changing the content of ACP/DA/Ag3 particles added to the OSA-GelDA gel, the corresponding performance of material was investigated. The results show that the introduction of dopamine provides wet viscosity for the hydrogel, and the ACP/DA/Ag3 particles introduced in the viscous hydrogel provide antibacterial properties. This hydrogel with antibacterial and wet viscosity is expected to become an injectable bone repair material for clinical use.

Use of Tisseel, a Fibrin Sealant, for Particulate Graft Stabilization

One clinical problem when augmenting a narrow or vertically deficient ridge is maintenance of the graft position during the immediate healing phase and preservation of the augmentation over time. The use of Tisseel (Baxter, Deerfield, IL), a fibrin sealant product, to stabilize particulate grafts, has been reported, and we have reviewed its use. Fibrinogen is converted to fibrin and forms a fibular network that binds the particulate graft. A protease inhibitor is included, which prevents lysis of the coagulum for at least 2 weeks and allows for fibrous ingrowth and graft stabilization. We have reviewed the reported data and included 2 case reports to demonstrate the use of Tisseel.