Preparation and characterization of small intestine submucosa powder impregnated poly(L-lactide) scaffolds: the application for tissue engineered bone and cartilage

Injectable biomimetic hydrogel based on modified chitosan and silk fibroin with decellularized cartilage extracellular matrix for cartilage repair and regeneration

Cartilage defect repair remains a challenge for clinicians due to the limited self-healing capabilities of cartilage. Microenvironment-specific biomimetic hydrogels have shown great potential in cartilage regeneration because of their excellent biological properties. In this study, a hydrogel system consisting of p-hydroxybenzene propanoic acid-modified chitosan (PC), silk fibroin (SF) and decellularized cartilage extracellular matrix (DCM) was prepared. Under the catalysis of horseradish peroxidase (HRP), the phenol hydroxyl groups on PC and SF were crosslinked to form a hydrogel. DCM incorporation into the hydrogel facilitated an emulation of the natural cartilage extracellular matrix. The synthesized injectable hydrogels could fill irregular defects and formed network structures that promoted cell adhesion and proliferation. In vitro experiments demonstrated that the hydrogels had biocompatibility and promoted chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). The DCM-derived hydrogel exhibited low immunogenicity in vivo, and in the treatment of both rabbit trochlear groove cartilage defects and goat femoral condyle cartilage defects, the hydrogel accelerated the cartilage regeneration. In summary, our developed composite hydrogel system in the study offers a potential strategy for the effective repair of cartilage defects.

Decellularization of Small Intestinal Submucosa

Small intestinal submucosa (SIS) is the most studied extracellular matrix (ECM) for repair and regeneration of different organs and tissues. Promising results of SIS-ECM as a vascular graft, led scientists to examine its applicability for repairing other tissues. Overall results indicated that SIS grafts induce tissue regeneration and remodeling to almost native condition. Investigating immunomodulatory effects of SIS is another interesting field of research. SIS can be utilized in different forms for multiple clinical and experimental studies. The aim of this chapter is to investigate the decellularization process of SIS and its common clinical application.

Applications of decellularized materials in tissue engineering: advantages, drawbacks and current improvements, and future perspectives

Decellularized materials (DMs) are attracting more and more attention because of their native structures, comparatively high bioactivity, low immunogenicity and good biodegradability, which are difficult to be imitated by synthetic materials. Recently, DMs have been demonstrated to possess great potential to overcome the disadvantages of autografts and have become a kind of promising material for tissue engineering. In this systematic review, we aimed to not only provide a quick access for understanding DMs, but also bring new ideas to utilize them more appropriately in tissue engineering. Firstly, the preparation of DMs was introduced. Then, the updated applications of DMs derived from different tissues and organs in tissue engineering were comprehensively summarized. In particular, their advantages, drawbacks and current improvements were emphasized. Moreover, we analyzed and proposed future perspectives.

Providing direction improves function: Comparison of a radial pore-orientated acellular collagen scaffold to clinical alternatives in a surgically induced rabbit diaphragmatic tissue defect model

Gore-Tex® is a widely used durable patch for repair of congenital diaphragmatic defects yet may result in complications. We compared Gore-Tex with a composite of a radial pore-orientated collagen scaffold (RP-Composite) and clinically used porcine small intestinal submucosa (SIS; Surgisis®) in a rabbit model for diaphragmatic hernia. The growing rabbit mimics the rapid rib cage growth and reherniation rates seen in children. We created and immediately repaired left hemidiaphragmatic defects in 6-week-old rabbits with Gore-Tex, SIS, and an RP-Composite scaffold. An additional group of rabbits had a sham operation. At 90 days, survivors more than doubled in weight. We observed few reherniations or eventrations in Gore-Tex (17%) and RP-Composite (22%) implanted animals. However, SIS failed in all rabbits. Maximum transdiaphragmatic pressure was lower in Gore-Tex (71%) than RP-Composite implanted animals (112%) or sham (134%). Gore-Tex repairs were less compliant than RP-Composite, which behaved as sham diaphragm (p < 0.01). RP-Composite induced less foreign body giant cell reaction than Gore-Tex (p < 0.05) with more collagen deposition (p < 0.001), although there was a tendency for the scaffold to calcify. Unlike Gore-Tex, the compliance of diaphragms reconstructed with RP-Composite scaffolds were comparable with native diaphragm, whereas reherniation rates and transdiaphragmatic pressure measurements were similar.

Collagen nanofibril self-assembly on a natural polymeric material for the osteoinduction of stem cells in vitro and biocompatibility in vivo

This manuscript reports the characterization of molecularly self-assembled collagen nanofibers on a natural polymeric microporous structure and their ability to support stem cell differentiation in vitro and host tissue response in vivo.

ATTACHMENT AND PROLIFERATION OF RETINAL PIGMENT EPITHELIAL CELLS ON SMALL INTESTINE SUBMUCOSA POWDER IMPREGNATED POLY(L-LACTIDE-CO-GLYCOLIDE) FILM

The retinal pigment epithelium (RPE) closely interacts with photoreceptors in the maintenance of visual function. The native RPEs exist as a monolayer structure and have a mottled brown color due to the presence of melanin and other pigments including lipofuscin granules, which accumulate with age. In age-related macular degeneration (AMD), RPE's dysfunction and changes in Bruch's membrane occur. Thus, small intestine submucosa/poly(lactic-co-glycolic acid) (SIS/PLGA) film is a biomimetic transplant consisting of a layer of healthy RPE cells cultured on a support membrane. The goals of this study were to evaluate the effects of attachment and proliferation of RPEs on SIS/PLGA films. Porcine SIS is an acellular tissue and widely used as a biomaterial without immunorejection responses, whereas PLGA is a biodegradable synthetic polymer with acceptable mechanical strength and well-controlled degradation rate. We fabricated SIS/PLGA films using 20 wt% of SIS. We measured MTT to confirm cellular adhesion of cell number attached on film at 1, 3, 5, and 7 days. Morphology of cellular adhesion on films was confirmed by scanning electron microscopy at 1, 3, and 7 days. Further, reverse transcription polymerase chain reaction (RT-PCR) was conducted to confirm messenger RNA expression of RPE65 as RPE's marker and expression of cytokeratin, and RPE65 were determined by AEC immunocytochemical staining. These results suggest that SIS provides suitable surface to RPEs.

Human extracellular matrix (ECM) powders for injectable cell delivery and adipose tissue engineering

Here, we present extracellular matrix (ECM) powders derived from human adipose tissue as injectable cell delivery carriers for adipose tissue engineering. We postulate that human adipose tissue may provide an ideal biomaterial because it contains large amounts of ECM components including collagen. Fresh human adipose tissue was obtained by a simple surgical operation (liposuction). After removing blood and oil components, the tissue was homogenized, centrifuged, freeze-dried, and ground to powders by milling. In an in vitro study, the human ECM powders were highly effective for promotion of cell attachment and proliferation for three-dimensional (3D) cell culture. In in vivo studies, suspensions of human ECM powders containing human adipose-derived stem cells (hASCs) were subcutaneously injected into nude mice. At eight weeks post-injection, numerous blood vessels were observed and the newly formed tissue exhibited adipogenesis with accumulated intracellular small lipid droplets. Overall, the grafts showed well-organized adipose tissue constructs without any signs of tissue necrosis, cystic spaces, or fibrosis. We believe that human ECM powders could act as efficient injectable biomaterials for tissue engineering and have great potential for meeting clinical challenges in regenerative medicine, particularly in relation to adipose tissue engineering.

Promotion of cell affinity of porous PLLA scaffolds by immobilization of RGD peptides via plasma treatment

In the present work, RGDS (Arg-Gly-Asp-Ser) was immobilized on PLLA scaffolds with plasma treatment. The amount of immobilization, determined by HPLC, was confirmed to be in the effective order. Results from the culture of rat osteosarcoma (ROS), osteoblastic-like cells, demonstrate that the immobilization of RGDS could effectively enhance the attachment of ROS cells on PLLA and increase the cell density in PLLA scaffolds. In addition, experiments of in vitro mineralization indicate that there were more cells and mineralization focci in the RGDS-immobilized scaffolds, suggesting a tendency to form bone-like tissues, compared with the unmodified PLLA scaffold. On the other hand, the PLLA scaffolds immobilized with RGES (Arg-Gly-Glu-Ser) were much less effective in promotion of ROS attachment, suggesting that the enhancement on cell attachment was mainly due to the recognition of RGDS by the adhesion receptors on the cell membrane. The results presented in this work demonstrate that RGDS could be successfully immobilized on PLLA scaffolds with plasma treatment and such modification can make PLLA scaffolds more suitable for culture of osteoblast-like cells and for generation of bone-like tissues.