Informatics challenges in tissue engineering and biomaterials

Discussing the final size and shape of the reconstructed tissues in tissue engineering

Tissue engineering (TE) has made a revolution in repairing, replacing, or regenerating tissues or organs, but it has still a long way ahead. The mechanical properties along with suitable physicochemical and biological characteristics are the initial criteria for scaffolds in TE that should be fulfilled. This research will provide another point of view toward TE challenges concerning the morphological and geometrical aspects of the reconstructed tissue and which parameters may affect it. Based on our survey, there is a high possibility that the final reconstructed tissue may be different in size and shape compared to the original design scaffold. Thereby, the 3D-printed scaffold might not guarantee an accurate tissue reconstruction. The main justification for this is the unpredicted behavior of cells, specifically in the outer layer of the scaffold. It can also be a concern when the scaffold is implanted while cell migration cannot be controlled through the in vivo signaling pathways, which might cause cancer challenges. To sum up, it is concluded that more studies are necessary to focus on the size and geometry of the final reconstructed tissue.

Comparative assessment of bone regeneration by histometry and a histological scoring system / Evaluarea comparativă a regenerării osoase utilizând histometria și un scor de vindecare histologică

Objective: The aim of this research is to evaluate the value of the histological score based on a histological record compared to the histometry for monitoring cranial bone defect healing. Methods: We designed a case -control study with a control and a study group. For a number of 60 CD1 mice representing the study group, a bone defect in the cranial bone was surgically induced and grafted with bone grafts obtained by tissue engineering. Bone grafts were obtained using embryonic stem cells seeded on a scaffold obtained from the red deer antler, and osteogenic basal and complex medium was used as differentiation medium. For other 30 CD1 mice representing the control group, a bone defect in the cranial bone was induced and left to heal without grafts. The regeneration process was assessed after 2 and 4 months using the histological healing scoring system and histometry. Results: The healing score was statistically significantly correlated with the defect size obtained by means of histometry (p<0.001). The evaluation of the parameters comprised in the healing score shows that regeneration of the bone diastasis was the most advanced in the group sacrificed at 4 months after plasty, which employed embryonic stem cells, a complex osteogenic differentiation medium and deer antler as scaffold. Conclusion: histological method based on a histological score is a valuable quantification system of bone regeneration comparable to histometry. Clinical Relevance: This study proves that the presented histological score can help the clinician in the process of bone regeneration evaluation.

EVA-enhanced embedding medium for histological analysis of 3D porous scaffold material

When sectioning a 3D porous scaffold made of a soft elastomeric material embedded in paraffin medium, it is not easy to obtain a section because of the different mechanical properties of the paraffin and tissue/scaffold. We describe a new embedding material for histological analysis of various biomaterials that is composed of paraffin and ethylene vinyl acetate (EVA) resin (0, 3, 7, and 13 wt.%). 3D porous poly(L-lactide-epsilon-caprolactone) (PLCL) and chitosan scaffolds were fabricated to test the sectioning efficiency of the paraffin/EVA embedding material. The new embedding material was characterized by rheological analysis and solvent solubility testing in xylene and n-hexane. The hydrophilicity of the new material was assessed by contact angle measurement and its surface roughness was measured using AFM analysis. The staining efficiency of sections embedded in a paraffin/EVA mixture was determined by eosin staining of the chitosan scaffold and chitosan/collagen hybrid scaffold using a fluorescently labeled collagen. Section roughness decreased with increasing EVA content. The softening temperature of the paraffin/EVA mixture was similar to that of paraffin (50-60 degrees C by rheometer). The paraffin/EVA mixture dissolved completely in xylene after 30min at 50 degrees C, and after 30min in n-hexane at 60 degrees C. Therefore, the new embedding medium can be used for histological analysis of various biomaterials and natural tissues.

Biocompatibility and the efficacy of medical implants

Biocompatibility is key to the performance of any material in a biological environment. This review outlines current opinion on the factors that lead to biocompatibility and focuses on the interactions that occur at the interface between material and environment. The sequence of events, from protein adsorption, cell attachment and behavior, to biocompatibility, is traced. Although these processes are studied and reported widely, there is, as yet, little published evidence that implant biocompatibility can be enhanced in the long term by surface engineering. This lack of evidence does not necessarily imply a lack of effect, but may be ascribed to a lack of robust characterization and poor modeling of the implant environment.