Generation and Evaluation of Novel Biomaterials Based on Decellularized Sturgeon Cartilage for Use in Tissue Engineering

Decellularization of fish tissues for tissue engineering and regenerative medicine applications

Decellularization is the process of obtaining acellular tissues with low immunogenic cellular components from animals or plants while maximizing the retention of the native extracellular matrix structure, mechanical integrity and bioactivity. The decellularized tissue obtained through the tissue decellularization technique retains the structure and bioactive components of its native tissue; it not only exhibits comparatively strong mechanical properties, low immunogenicity and good biocompatibility but also stimulates in situ neovascularization at the implantation site and regulates the polarization process of recruited macrophages, thereby promoting the regeneration of damaged tissue. Consequently, many commercial products have been developed as promising therapeutic strategies for the treatment of different tissue defects and lesions, such as wounds, dura, bone and cartilage defects, nerve injuries, myocardial infarction, urethral strictures, corneal blindness and other orthopedic applications. Recently, there has been a growing interest in the decellularization of fish tissues because of the abundance of sources, less religious constraints and risks of zoonosis transmission between mammals. In this review, we provide a complete overview of the state-of-the-art decellularization of fish tissues, including the organs and methods used to prepare acellular tissues. We enumerated common decellularized fish tissues from various fish organs, such as skin, scale, bladder, cartilage, heart and brain, and elaborated their different processing methods and tissue engineering applications. Furthermore, we presented the perspectives of (i) the future development direction of fish tissue decellularization technology, (ii) expanding the sources of decellularized tissue and (iii) innovating decellularized tissue bio-inks for 3D bioprinting to unleash the great potential of decellularized tissue in tissue engineering and regenerative medicine applications.

Spatiotemporal characterization of extracellular matrix maturation in human artificial stromal-epithelial tissue substitutes

BACKGROUND

Tissue engineering techniques offer new strategies to understand complex processes in a controlled and reproducible system. In this study, we generated bilayered human tissue substitutes consisting of a cellular connective tissue with a suprajacent epithelium (full-thickness stromal-epithelial substitutes or SESS) and human tissue substitutes with an epithelial layer generated on top of an acellular biomaterial (epithelial substitutes or ESS). Both types of artificial tissues were studied at sequential time periods to analyze the maturation process of the extracellular matrix.

RESULTS

Regarding epithelial layer, ESS cells showed active proliferation, positive expression of cytokeratin 5, and low expression of differentiation markers, whereas SESS epithelium showed higher differentiation levels, with a progressive positive expression of cytokeratin 10 and claudin. Stromal cells in SESS tended to accumulate and actively synthetize extracellular matrix components such as collagens and proteoglycans in the stromal area in direct contact with the epithelium (zone 1), whereas these components were very scarce in ESS. Regarding the basement membrane, ESS showed a partially differentiated structure containing fibronectin-1 and perlecan. However, SESS showed higher basement membrane differentiation, with positive expression of fibronectin 1, perlecan, nidogen 1, chondroitin-6-sulfate proteoglycans, agrin, and collagens types IV and VII, although this structure was negative for lumican. Finally, both ESS and SESS proved to be useful tools for studying metabolic pathway regulation, revealing differential activation and upregulation of the transforming growth factor-β pathway in ESS and SESS.

CONCLUSIONS

These results confirm the relevance of epithelial-stromal interaction for extracellular matrix development and differentiation, especially regarding basement membrane components, and suggest the usefulness of bilayered artificial tissue substitutes to reproduce ex vivo the extracellular matrix maturation and development process of human tissues.

Preliminary evaluation of fish cartilage as a promising biomaterial in cartilage tissue engineering

Fish cartilage is known as a valuable source of natural biomaterials due to its unique composition and properties. It contains a variety of bioactive components that contribute to its potential applications in different domains such as tissue engineering. The present work aimed to consider the properties of backbone cartilage from fish with a cartilaginous skeleton, including elasmobranch (reticulate whipray: Himantura uarnak and milk shark: Rhizoprionodon acutus) and sturgeon (beluga: Huso huso). The histomorphometric findings showed that the number of chondrocytes was significantly higher in reticulate whipray and milk shark compared to beluga (p < 0.05). The highest GAGs content was recorded in reticulate whipray cartilage compared to the other two species (p < 0.05). The cartilage from reticulate whipray and beluga showed higher collagen content than milk shark cartilage (p < 0.05), and the immunohistochemical assay for type II collagen (Col II) showed higher amounts of this component in reticulate whipray compared to the other two species. Young's modulus of the cartilage from reticulate whipray was significantly higher than that of milk shark and beluga (p < 0.05), while no significant difference was recorded between Young's modulus of the cartilage from milk shark and beluga. The gene expression of ACAN, Col II, and Sox9 showed that the cartilage-ECM from three species was able to induce chondrocyte differentiation from human adipose tissue-derived stem cells (hASCs). From these results, it can be concluded that the cartilage from three species, especially reticulate whipray, enjoys the appropriate biological properties and provides a basis for promoting its applications in the field of cartilage tissue engineering.

Natural based hydrogels promote chondrogenic differentiation of human mesenchymal stem cells

Background: The cartilage tissue lacks blood vessels, which is composed of chondrocytes and ECM. Due to this vessel-less structure, it is difficult to repair cartilage tissue damages. One of the new methods to repair cartilage damage is to use tissue engineering. In the present study, it was attempted to simulate a three-dimensional environment similar to the natural ECM of cartilage tissue by using hydrogels made of natural materials, including Chitosan and different ratios of Alginate. Material and methods: Chitosan, alginate and Chitosan/Alginate hydrogels were fabricated. Fourier Transform Infrared, XRD, swelling ratio, porosity measurement and degradation tests were applied to scaffolds characterization. After that, human adipose derived-mesenchymal stem cells (hADMSCs) were cultured on the hydrogels and then their viability and chondrogenic differentiation capacity were studied. Safranin O and Alcian blue staining, immunofluorescence staining and real time RT-PCR were used as analytical methods for chondrogenic differentiation potential evaluation of hADMSCs when cultured on the hydrogels. Results: The highest degradation rate was detected in Chitosan/Alginate (1:0.5) group The scaffold biocompatibility results revealed that the viability of the cells cultured on the hydrogels groups was not significantly different with the cells cultured in the control group. Safranin O staining, Alcian blue staining, immunofluorescence staining and real time PCR results revealed that the chondrogenic differentiation potential of the hADMSCs when grown on the Chitosan/Alginate hydrogel (1:0.5) was significantly higher than those cell grown on the other groups. Conclusion: Taken together, these results suggest that Chitosan/Alginate hydrogel (1:0.5) could be a promising candidate for cartilage tissue engineering applications.

Histological characterization of the human scapholunate ligament

The scapholunate interosseous ligament (SLIL) plays a fundamental role in stabilizing the wrist bones, and its disruption is a frequent cause of wrist arthrosis and disfunction. Traditionally, this structure is considered to be a variety of fibrocartilaginous tissue and consists of three regions: dorsal, membranous and palmar. Despite its functional relevance, the exact composition of the human SLIL is not well understood. In the present work, we have analyzed the human SLIL and control tissues from the human hand using an array of histological, histochemical and immunohistochemical methods to characterize each region of this structure. Results reveal that the SLIL is heterogeneous, and each region can be subdivided in two zones that are histologically different to the other zones. Analysis of collagen and elastic fibers, and several proteoglycans, glycoproteins and glycosaminoglycans confirmed that the different regions can be subdivided in two zones that have their own structure and composition. In general, all parts of the SLIL resemble the histological structure of the control articular cartilage, especially the first part of the membranous region (zone M1). Cells showing a chondrocyte-like phenotype as determined by S100 were more abundant in M1, whereas the zone containing more CD73-positive stem cells was D2. These results confirm the heterogeneity of the human SLIL and could contribute to explain why certain zones of this structure are more prone to structural damage and why other zones have specific regeneration potential. RESEARCH HIGHLIGHTS: Application of an array of histological analysis methods allowed us to demonstrate that the human scapholunate ligament is heterogeneous and consists of at least six different regions sharing similarities with the human cartilage, ligament and other anatomical structures.

Histological characterization of the human masticatory oral mucosa. A histochemical and immunohistochemical study

BACKGROUND

Histology of human oral mucosa is closely related with its function and anatomical location, and a proper characterization of the human masticatory oral mucosa could be very useful in periodontal pathology.

OBJECTIVE

In the present work, we have carried out a comprehensive study in order to determine the main histological features of parakeratinized (POM) and orthokeratinized (OOM) masticatory human oral mucosa using light and electron microscopy.

METHODS

To perform this, we have used several histological, histochemical and immunohistochemical methods to detect key markets at the epithelial, basement membrane and connective tissue levels.

RESULTS

Our results demonstrated that POM and OOM share many histological similarities, as expected. However, important differences were observed at the epithelial layer of POM, that was significantly thicker than the epithelial layer found in OOM, especially due to a higher number of cells at the stratum spinosum. The expression pattern of CK10 and filaggrin revealed intense signal expression in OOM as compared to POM. Collagen and proteoglycans were more abundant in OOM stroma than in POM. No differences were found for blood vessels and basement membrane.

CONCLUSION

These results may contribute to a better understanding of the pathological conditions affecting the human masticatory oral mucosa. In addition, these findings could be useful for the generation of different types of oral mucosa by tissue engineering techniques.

RESEARCH HIGHLIGHTS

Microscopical features of parakeratinized and orthokeratinized masticatory human oral mucosa showed important differences at both, epithelial and stromal levels. Parakeratinized masticatory human oral mucosa exert thicker epithelial layer, especially, at the stratum spinosum in comparison to orthokeratinized human oral mucosa. Cytokeratin 10 and filaggrin human epithelial markers were intensively expressed in orthokeratinized masticatory human oral mucosa in comparison to parakeratinized masticatory human oral mucosa. At the stromal level, orthokeratinized masticatory human oral mucosa exhibit higher levels of collagen and proteoglycans than parakeratinized masticatory oral mucosa. The deep knowledge of histological features of masticatory oral mucosa could lead to a better understanding of oral mucosa pathology and advanced treatments.

Optical Behavior of Human Skin Substitutes: Absorbance in the 200-400 nm UV Range

The most recent generation of bioengineered human skin allows for the efficient treatment of patients with severe skin defects. Despite UV sunlight can seriously affect human skin, the optical behavior in the UV range of skin models is still unexplored. In the present study, absorbance and transmittance of the UGRSKIN bioartificial skin substitute generated with human skin cells combined with fibrin-agarose biomaterials were evaluated for: UV-C (200−280 nm), -B (280−315 nm), and -A (315−400 nm) spectral range after 7, 14, 21 and 28 days of ex vivo development. The epidermis of the bioartificial skin substitute was able to mature and differentiate in a time-dependent manner, expressing relevant molecules able to absorb most of the incoming UV radiation. Absorbance spectral behavior of the skin substitutes showed similar patterns to control native skin (VAF > 99.4%), with values 0.85−0.90 times lower than control values at 7 and 14- days and 1.05−1.10 times the control values at 21- and 28-days. UV absorbance increased, and UV transmission decreased with culture time, and comparable results to the control were found at 21 and 28 days. These findings support the use of samples corresponding to 21 or 28 days of development for clinical purposes due to their higher histological similarities with native skin, but also because of their absorbance of UV radiation.