Development of a Two-Layer Porous Scaffold Based on Porcine Nasal Septal Cartilage for Orthopedics.

The aim of the study was to design a construct based on a nasal septal cartilage plate providing required cell differentiation in different layers to replace a deep osteochondral defect and develop an algorithm of chemical and physical effect sequence to create non-immunogenic two-layer porous structure with requisite elasto-mechanical properties.

Materials and methods: The plates derived from porcine nasal septal hyaline cartilage covered by perichondrium were multi-stage treated including freezing, equilibrating in a hypotonic saline solution (type I specimens); trypsinization, point IR-laser effect, re-trypsinization (type II specimens); a stabilizing effect of crosslinking agents - glyceraldehyde/ribose in an acidic medium - washing (type III specimens).For all type specimens:there were established stability parameters (collagen denaturation temperature using a thermal analysis; and Young's modulus using a mechanical analysis);there were determined morphological characteristics using light and polarization microscopy with classical staining and nonlinear optical microscopy in second-harmonic generation mode.

Results: Thermal, mechanical, and morphological properties in type I specimens slightly differed from those of the initial nasoseptal system. A considerable part of cells had destroyed membranes.In type II specimens, thermal stability of collagen frame was significantly lower; Young's modulus decreased more than fourfold compared to type I specimens. Collagen structure of hyaline cartilage appeared to be disarranged, although the morphological differences of the hyaline part and perichondrium preserved. The construct matrix was almost completely decellularized. Successive exposure to laser radiation and trypsin resulted in the formation of partial holes in the matrix, ~100 μm in diameter.In type III specimens, both the thermal stability of the collagen frame and Young's modulus (E) increased. Glyceraldehyde was more effective than ribose, E having reached the value typical for intact hyaline cartilage. Collagen fibers in type III specimens were thicker than in type I and II specimens. The morphological differences of the hyaline part and perichondrium and partial holes were preserved.

Conclusion: Due to sequential treatment by salts, trypsin, IR-laser radiation, and nontoxic crosslinking agents, nasal septal cartilage plate forms porous acellular construction consisting of two layers formed by type I (from perichondrium) and type II (from hyaline part) collagen fibers. In the present construction, stability, mechanical properties, and size of the partial holes can be assigned for cell colonization. It enables to use the construction to replace articular cartilage defects.