Gelatin-poly(lactic-co-glycolic acid) scaffolds with oriented pore channel architecture — From in vitro to in vivo testing

Orthobiologics: a review

PURPOSE

The use of biologic materials in orthopaedics (orthobiologics) has gained significant attention over the past years. To enhance the body of the related literature, this review article is aimed at summarizing these novel biologic therapies in orthopaedics and at discussing their multiple clinical implementations and outcomes.

METHODS

This review of the literature presents the methods, clinical applications, impact, cost-effectiveness, and outcomes, as well as the current indications and future perspectives of orthobiologics, namely, platelet-rich plasma, mesenchymal stem cells, bone marrow aspirate concentrate, growth factors, and tissue engineering.

RESULTS

Currently available studies have used variable methods of research including biologic materials as well as patient populations and outcome measurements, therefore making comparison of studies difficult. Key features for the study and use of orthobiologics include minimal invasiveness, great healing potential, and reasonable cost as a nonoperative treatment option. Their clinical applications have been described for common orthopaedic pathologies such as osteoarthritis, articular cartilage defects, bone defects and fracture nonunions, ligament injuries, and tendinopathies.

CONCLUSIONS

Orthobiologics-based therapies have shown noticeable clinical results at the short- and mid-term. It is crucial that these therapies remain effective and stable in the long term. The optimal design for a successful scaffold remains to be further determined.

Functional Biomolecule Delivery Systems and Bioengineering in Cartilage Regeneration

Osteoarthritis (OA) is a common degenerative disease which involves articular cartilage, and leads to total joint disability in the advanced stages. Due to its avascular and aneural nature, damaged cartilage cannot regenerate itself. Stem cell therapy and tissue engineering represent a promising route in OA therapy, in which cooperation of mesenchymal stem cells (MSCs) and three-dimensional (3D) scaffolds contribute to cartilage regeneration. However, this approach still presents some limits such as poor mechanical properties of the engineered cartilage. The natural dynamic environment of the tissue repair process involves a collaboration of several signals expressed in the biological system in response to injury. For this reason, tissue engineering involving exogenous "influencers" such as mechanostimulation and functional biomolecule delivery systems (BDS), represent a promising innovative approach to improve the regeneration process. BDS provide a controlled release of biomolecules able to interact between them and with the injured tissue. Nano-dimensional BDS is the future hope for the design of personalized scaffolds, able to overcome the delivery problems. MSC-derived extracellular vesicles (EVs) represent an attractive alternative to BDS, due to their innate targeting abilities, immunomodulatory potential and biocompatibility. Future advances in cartilage regeneration should focus on multidisciplinary strategies such as modular assembly strategies, EVs, nanotechnology, 3D biomaterials, BDS, mechanobiology aimed at constructing the functional scaffolds for actively targeted biomolecule delivery. The aim of this review is to run through the different approaches adopted for cartilage regeneration, with a special focus on biomaterials, BDS and EVs explored in terms of their delivery potential, healing capabilities and mechanical features.

Influence of the PLGA/gelatin ratio on the physical, chemical and biological properties of electrospun scaffolds for wound dressings

Chronic wounds are a global health problem, and their treatments are difficult and long lasting. The development of medical devices through tissue engineering has been conducted to heal this type of wound. In this study, it was demonstrated that the combination of natural and synthetic polymers, such as poly (D-L lactide-co-glycolide) (PLGA) and gelatin (Ge), were useful for constructing scaffolds for wound healing. The aim of this study was to evaluate the influence of different PLGA/gelatin ratios (9:1, 7:3 and 5:5 (v/v)) on the physical, chemical and biological properties of electrospun scaffolds for wound dressings. These PLGA/Ge scaffolds had randomly oriented fibers with smooth surfaces and exhibited distances between fibers of less than 10 μm. The 7:3 and 5:5 PLGA/Ge scaffolds showed higher swelling, hydrophilicity and degradation rates than pure PLGA and 9:1 (v/v) PLGA/Ge scaffolds. Young's moduli of the scaffolds were 72 ± 10, 48 ± 6, 58 ± 6 and 6 ± 1 MPa for the pure PLGA scaffold and the 9:1, 7:3 and 5:5 (v/v) PLGA/Ge scaffolds, respectively. Mesenchymal stem cells (MSCs) seeded on all the PLGA/Ge scaffolds were viable, and the cells were attached to the fibers at the different analyzed timepoints. The most significant proliferation rate was observed for cells on the 7:3 PLGA/Ge scaffolds. Biocompatibility analysis showed that all the scaffolds produced inflammation at the first week postimplantation; however, the 7:3 and 5:5 (v/v) PLGA/Ge scaffolds were degraded completely, and there was no inflammatory reaction observed at the fourth week after implantation. In contrast, the 9:1 PLGA/Ge scaffolds persisted in the tissue for more than four weeks; however, at the eighth week, no traces of the scaffolds were found. In conclusion, the scaffolds with the 7:3 PLGA/Ge ratio showed suitable physical, chemical and biological properties for applications in chronic wound treatments.

Enhanced chondrogenic differentiation of bone marrow mesenchymal stem cells on gelatin/glycosaminoglycan electrospun nanofibers with different amount of glycosaminoglycan

Tissue engineering is a new technique to help damaged cartilage treatment using cells and scaffolds. In this study we tried to evaluate electrospun scaffolds composed of gelatin/glycosaminoglycan (G/GAG) blend nanofibers in chondrogenesis of bone marrow-derived mesenchymal stem cells (BMMSCs). Scaffolds were fabricated by electrospinning technique with different concentration of glycosaminoglycan (0%, 5%, 10%, and 15%) in gelatin matrix. BMMSCs were cultured on the scaffolds for chondrogenesis process. MTT assay was done for scaffold's biocompatibility and cells viability evaluation. Alcian blue staining was carried out to determine the release of GAG and reverse transcription polymerase chain reaction (RT-PCR) was done for expression of COL2A1 and also immunocytochemistry assay were used to confirm expression of type II collagen. Scaffold with 15% GAG showed better result for biocompatibility (p =0.02). Scanning electron microscopy (SEM) micrographs showed that MSCs have good attachment to the scaffolds. Alcian blue staining result confirmed that cells produce GAG during differentiation time different from GAG in the scaffolds. Also the results for RT-PCR showed the expression of COL2A1 marker. Immunocytochemistry assay for type II collagen confirm that this protein expressed. Scaffold comprising 15% GAG is better results for chondrogenesis and it can be a good applicant for cartilage tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 38-48, 2019.

Current Therapeutic Strategies for Stem Cell-Based Cartilage Regeneration

The process of cartilage destruction in the diarthrodial joint is progressive and irreversible. This destruction is extremely difficult to manage and frustrates researchers, clinicians, and patients. Patients often take medication to control their pain. Surgery is usually performed when pain becomes uncontrollable or joint function completely fails. There is an unmet clinical need for a regenerative strategy to treat cartilage defect without surgery due to the lack of a suitable regenerative strategy. Clinicians and scientists have tried to address this using stem cells, which have a regenerative potential in various tissues. Cartilage may be an ideal target for stem cell treatment because it has a notoriously poor regenerative potential. In this review, we describe past, present, and future strategies to regenerate cartilage in patients. Specifically, this review compares a surgical regenerative technique (microfracture) and cell therapy, cell therapy with and without a scaffold, and therapy with nonaggregated and aggregated cells. We also review the chondrogenic potential of cells according to their origin, including autologous chondrocytes, mesenchymal stem cells, and induced pluripotent stem cells.

Recent strategies in cartilage repair: A systemic review of the scaffold development and tissue engineering

Osteoarthritis results in irreparable loss of articular cartilage. Due to its avascular nature and low mitotic activity, cartilage has little intrinsic capacity for repair. Cartilage loss leads to pain, physical disability, movement restriction, and morbidity. Various treatment strategies have been proposed for cartilage regeneration, but the optimum treatment is yet to be defined. Tissue engineering with engineered constructs aimed towards developing a suitable substrate may help in cartilage regeneration by providing the mechanical, biological and chemical support to the cells. The use of scaffold as a substrate to support the progenitor cells or autologous chondrocytes has given promising results. Leakage of cells, poor cell survival, poor cell differentiation, inadequate integration into the host tissue, incorrect distribution of cells, and dedifferentiation of the normal cartilage are the common problems in tissue engineering. Current research is focused on improving mechanical and biochemical properties of scaffold to make it more efficient. The aim of this review is to provide a critical discussion on existing challenges, scaffold type and properties, and an update on ongoing recent developments in the architecture and composition of scaffold to enhance the proliferation and viability of mesenchymal stem cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2343-2354, 2017.

Strontium doped poly-ε-caprolactone composite scaffolds made by reactive foaming

In the reconstruction and regeneration of bone tissue, a primary goal is to initiate bone growth and to stabilize the surrounding bone. In this regard, a potentially useful component in biomaterials for bone tissue engineering is strontium, which acts as cationic active agent, triggering certain intracellular pathways and acting as so called dual action bone agent which inhibits bone resorption while stimulating bone regeneration. In this study we established a novel processing for the foaming of a polymer (poly-ε-caprolactone) and simultaneous chemical reaction of a mixture of calcium and strontium hydroxides to the respective carbonates using supercritical carbon dioxide. The resultant porous composite scaffold was optimized in composition and strontium content and was characterized via different spectroscopic (infrared and Raman spectroscopy, energy dispersive X-ray spectroscopy), imaging (SEM, μCT), mechanical testing and in vitro methods (fluorescence vital staining, MTT-assay). As a result, the composite scaffold showed good in vitro biocompatibility with partly open pore structure and the expected chemistry. First mechanical testing results indicate sufficient mechanical stability to support future in vivo applications.