Creating artificial perichondrium by polymer complex membrane macroencapsulation: immune protection and stabilization of subcutaneously transplanted tissue-engineered cartilage

Perichondrium directed cartilage formation in silk fibroin and chitosan blend scaffolds for tracheal transplantation

The purpose of this study was to investigate the potential of silk fibroin and chitosan blend (SFCS) biological scaffolds for the purpose of cartilage tissue engineering with applications in tracheal tissue reconstruction. The capability of these scaffolds as cell carrier systems for chondrocytes was determined in vitro and cartilage generation in vivo on engineered chondrocyte-scaffold constructs with and without a perichondrium wrapping was tested in an in vivo nude mouse model. SFCS scaffolds supported chondrocyte adhesion, proliferation, and differentiation, determined as features of the cells based on the spherical cell morphology, increased accumulation of glycosaminoglycans, and increased collagen type II deposition with time within the scaffold framework. Perichondrium wrapping significantly (P<0.001) improved chondrogenesis within the cell-scaffold constructs in vivo. In vivo implantation for 6weeks did not generate cartilage structures resembling native trachea, although cartilage-like structures were present. The mechanical properties of the regenerated tissue increased due to the deposition of chondrogenic matrix within the SFCS scaffold structural framework of the trachea. The support of chondrogenesis by the SFCS tubular scaffold construct resulted in a mechanically sound structure and thus is a step towards an engineered trachea that could potentially support the growth of an epithelial lining resulting in a tracheal transplant with properties resembling those of the fully functional native trachea.

Tissue-engineered larynx using perfusion-decellularized technique and mesenchymal stem cells in a rabbit model

CONCLUSION

Reseeding mesenchymal stem cells (MSCs) into the decellularized laryngeal muscle matrix for construction of a tissue-engineered larynx is feasible. This in vivo maturation in the omentum could be the first step before in situ implantation of the construct. This construct could facilitate a tissue-engineered method for laryngeal reconstruction.

OBJECTIVES

The extracellular matrix (ECM) and MSCs have been widely used for organ reconstruction. Our study aimed to prepare a soft tissue decellularized laryngeal scaffold with intact laryngeal cartilages utilizing a perfusion-decellularized technique, reseeding cells on it, and then construct a recellularized larynx.

METHODS

Perfusion-decellularized larynges were obtained from 20 rabbits by perfusion of the common carotid arteries with detergents. Twelve perfused larynges were observed by macroscopic visualization, histological examination, scanning electron microscopy (SEM), and cartilage viability. The remaining eight perfusion constructs were reseeded with induced MSCs aspirated from eight receptor rabbits. Composites were transferred into greater omentums of receptor rabbits after adherence for 1 day in vitro. Rabbit larynges were harvested after 4 weeks and 8 weeks, respectively. Macroscopic visualization, histological examination, and immunohistochemistry were performed.

RESULTS

Larynges perfused by sodium dodecyl sulfate became transparent after 2 h of perfusion. Histology and SEM indicated that the perfusion method showed a better decullularized effect. Almost no intact cells or nuclei were found, while more pores and collagen fibers were retained in the decellularized matrix. The chondrocyte vitality assay indicated that chondrocyte vitality was high. Vascularization was clearly seen by 4 weeks and relatively integrated cartilage frameworks remained by 8 weeks. Histological and immunohistochemical examinations clearly showed muscle bundles and vessels.

Common skeletal growth retardation disorders resulting from abnormalities within the mesenchymal stem cells reservoirs in the epiphyseal organs pertaining to the long bones

Among the objectives in writing the current chapter were the curiosity and the interest in allocating the sites and routes of migration of the reservoirs of the mesenchymal precartilaginous stem cells of the developing limbs in health and in disease. We chose to emphasize the events believed to initiate in these regions of stem cells, which may lead to growth retardation disorders. Thus, this narrow niche touches an enlarged scope of developmental biology angles and fields. The enclosed coverage sheds light on part of the musculoskeletal system, skeletogenesis, organogenesis of mobile structures and organs, the limbs, joints and digits (arthrology). It appears that the key role of the cartilage-bone regions is their responsibility to replenish the physis with committed chondrocytes, during the developmental, maturation and puberty periods. We shall start by outlining the framework of normal limb formation, the modalities, signals and the agents participating in this biological creation and regulation, illustrating potential sites that might deviate from normal development during the growth periods.

Tissue engineered prefabricated vascularized flaps

BACKGROUND.: Microvascular free tissue transfer has become increasingly popular in the reconstruction of head and neck defects, but it also has its disadvantages. Tissue engineering allows the generation of neo-tissue for implantation, but these tissues are often avascular. We propose to combine tissue-engineering techniques together with flap prefabrication techniques to generate a prefabricated vascularized soft tissue flap.

METHODS

Human dermal fibroblasts (HDFs) labeled with fluorescein diacetate were static seeded onto polylactic-co-glycolic acid-collagen (PLGA-c) mesh. Controls were plain PLGA-c mesh. The femoral artery and vein of the nude rat was ligated and used as a vascular carrier for the constructs. After 4 weeks of implantation, the constructs were assessed by gross morphology, routine histology, Masson trichrome, and cell viability determined by green fluorescence.

RESULTS

All the constructs maintained their initial shape and dimensions. Angiogenesis was evident in all the constructs with neo-capillary formation within the PLGA-c mesh seen. HDFs proliferated and filled the interyarn spaces of the PLGA-c mesh, while unseeded PLGA-c mesh remained relatively acellular. Cell tracer study indicated that the seeded HDFs remained viable and closely associated to remaining PLGA-c fibers. Collagen formation was more abundant in the constructs seeded with HDFs.

CONCLUSIONS

PLGA-c, enveloped by a cell sheet composed of fibroblasts, can serve as a suitable scaffold for generation of a soft tissue flap. A ligated arteriovenous pedicle can serve as a vascular carrier for the generation of a tissue engineered vascularized flap.