Viability and Biomechanics of Bare Diced Cartilage Grafts in Experimental Study:

Mechanical properties of extensive calcified costal cartilage: An experimental study

Background

Autologous costal cartilage is widely used as nasal augmentation or nasal reconstruction material. However, no study has focused on the mechanical difference between no calcified costal cartilage and extensive calcified costal cartilage at present. Our study aims to study the loading behavior of calcified costal cartilage under tensile and compressive stress.

Method

Human costal cartilage specimen was obtained from five extensive calcified costal cartilage patients and classified into four groups (group A: no calcified costal cartilage; group B: calcified costal cartilage; group C: no calcified costal cartilage after transplantation in BALB/c nude mice for half a year; group D: calcified costal cartilage after transplantation in BALB/c nude mice for half a year). Young's modulus, stress relaxation slope, and relaxation amount were analyzed through tensile and compressive tests using a material testing machine.

Results

We included five female patients with extensive calcified costal cartilage. Group B exhibited significantly higher Young's modulus in both the tensile and compressive tests (p < 0.05 in tensile test, p < 0.01 in compressive test), higher relaxation slope (P < 0.01) and higher relaxation amount (p < 0.05 in compression test). After transplantation, the Young's modulus of calcified and non-calcified costal cartilage decreased, except that the calcified costal cartilage increased slightly in the tensile test. The final relaxation slope and relaxation amount had increased at different degrees, but the changes did not change significantly before and after transplantation (P > 0.05).

Conclusion

Our results showed that the stiffness of calcified cartilage would increase 30.06% under tension and 126.31% under compression. This study may provide new insights to researchers focusing on extensive calcified costal cartilage can be used for autologous graft material.

Effect of Stromal Vascular Fractions on Angiogenesis of Injected Diced Cartilage

Objectives:

This study explored the effect of adipose-derived stromal vascular fractions (SVFs) on angiogenesis in injected autologous diced cartilage.

Methods:

Stromal vascular fractions were extracted by enzymatic digestion. Cartilage grafts were harvested from 1 side of the auricular cartilage of New Zealand rabbit and then diced to a size of 1.0 mm³. The grafts were divided into 2 groups. The control group was diced cartilage mixed with culture medium, and the experimental group was diced cartilage mixed with SVFs. The 2 groups of composite grafts were subcutaneously implanted on both sides of the back of each rabbit. After 4, 12 and 24 weeks, the tissue structure, number of blood vessels, and angiogenic factors in the grafts were observed.

Results:

The SVFs conformed to the current standard of the biological evaluation. Under an inverted microscope, the number of layers of chondrocytes in the experimental group was higher than that in the control group at 4 weeks. A small number of inflammatory cells and blood vessels were observed around the cartilage grafts. At 12 and 24 weeks, the volume of tissue was increased gradually by general observation. And a large number of chondrocytes were observed microscopically, whereas the number of inflammatory cells decreased. And meanwhile additional new blood vessels were observed. Immunohistochemical analysis of CD31 showed that the number of capillaries in the control group was significantly lower than that in the experimental group at 4, 12 and 24 weeks. Further, the expression of Hypoxia inducible factor-1 (HIF-1) and vascular endothelial growth factor (VEGF) mRNA and protein were measured by RT-PCR and Western bloting, respectively. The results showed that the mRNA expression of VEGF and HIF-1α in the experimental group was increased. The mRNA level remained higher than that of the control group at 24 weeks (P < 0.05). And the relative expression levels of VEGF and HIF-1α protein in the experimental group were higher than those in the control group at 4, 12 and 24 weeks (P < 0.05).

Conclusion:

Autologous diced cartilage mixed with adipose-derived SVFs can promote angiogenesis when transplanted by injection. Further research showed that SVFs could increase the expression levels of VEGF and HIF-1α in the grafts, which may be part of the mechanism that SVFs promoted the angiogenesis of diced cartilage.

Effects of Esterified Hyaluronic Acid, Adipose Tissue, and Blood Glue on Survival of Diced Cartilage Grafts

OBJECTIVES

Diced cartilage grafts are used for correcting nasal dorsal deformities and irregularities. However, cartilage resorption is among most common problems after rhinoplasty. The purpose of this experimental study was to investigate the effects of esterified hyaluronic acid, adipose tissue, and blood glue on the viability of diced cartilage grafts.

METHODS

A total of 24 Wistar albino rats were used for the study. Cartilage grafts were obtained from 1 side ear and diced. The rats were divided into 4 groups (6 in each group): bare diced cartilage (group 1), diced cartilage wrapped with adipose tissue (group 2), diced cartilage blended with blood glue (group 3), and diced cartilage wrapped with esterified hyaluronic acid (group 4). The grafts were inserted into the subcutaneous pockets of the back of same rat. After 2 months follow-up specimens were harvested for histopathological and dimensional examination. The sections were stained with Hematoxylin and Eosin, Masson-Trichrome, and Elastic Van-Gieson. Chronic inflammation, loss of chondrocyte nucleus, vascularization, foreign body reaction, collagen content of matrix, and extent of elastic fiber were assessed under light microscopy.

RESULTS

Foreign body reaction in adipose tissue and blood group was significantly higher than bare cartilage and esterified hyaluronic acid group (P = 0.001). With respect to loss of chondrocyte nucleus esterified hyaluronic acid group had significant higher rate of nucleus loss than other groups (P = 0.002).

CONCLUSIONS

This study suggests that blood glue, esterified hyaluronic acid and autologous adipose tissue have not beneficial effects in improving viability of diced cartilage grafts.

Long-Term Complications from Diced Cartilage in Rhinoplasty: A Meta-analysis

Objective: To analyze the incidences of long-term complications and revision surgery associated with diced cartilage grafts in dorsal augmentation rhinoplasty. Methods: The PubMed, MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases were searched for clinical studies on the use of diced cartilage for dorsal augmentation published. A meta-analysis was conducted to pool the estimated rates of infection, overcorrection, visible irregularity, absorption, and revision surgery. Result: A total of 14 studies involving 2380 patients were included in the systematic review. The combined rates were 11.5% for overall complications and 5.3% for revision surgery. The rates of the most frequently reported complications were 4.5% for infection, 5.3% for visible irregularity, 0.7% for overcorrection, and 0.5% for absorption. There was no significant difference in the rates of visible irregularity (p = 0.23) and revision surgery (p = 0.71) among the wrapped diced cartilage, glued diced cartilage, and free diced cartilage groups. Conclusion: This meta-analysis presents the first comprehensive and quantitative report of long-term complications associated with diced cartilage in dorsal augmentation rhinoplasty. Infection and visible irregularity were the most frequently reported complications. The rates of irregularity and revision surgery were not correlated with the diced cartilage packing methods.

The Effect of Perichondrium on Biological and Biomechanical Properties of Molded Diced Cartilage Grafts

BACKGROUND

Diced cartilage is a significant alternative approach to cartilage grafting. However, the viability and biomechanical properties of diced cartilage grafts remain to be improved, and the role of perichondrium is largely neglected. This study aimed to evaluate the histological and biomechanical effects of perichondrium on custom-shaped diced cartilage grafts constructed via a high-density porous polyethylene mold.

METHODS

Seven New Zealand rabbits were used. Unilateral auricular cartilage was harvested and divided into 2 parts, with or without perichondrium, diced into 1 × 1 × 0.5 mm cubical pieces, and filled into high-density porous polyethylene molds. Three grafts with the perichondrium removed and 3 with the perichondrium preserved were implanted subcutaneously at the dorsum. The grafts underwent biomechanical and histological tests 4, 8, and 12 weeks after the implantation.

RESULTS

The diced cartilage merged into integrated blocks without observable resorption in both groups at each time point. Additionally, the retention rate of weight was higher in the perichondrium-preserved group (P < 0.05). We observed regenerated cartilage that stained positively for type II collagen and glial fibrillary acidic protein (GFAP). A greater area of regenerated cartilage and higher scores of GFAP staining were observed in the perichondrium-preserved group (P < 0.05). The yield stress and modulus of elasticity were also higher in the perichondrium-preserved grafts from week 8 after implantation (P < 0.05).

CONCLUSIONS

Diced cartilage grafts with a custom shape can be constructed using a high-density porous polyethylene mold. The preservation of perichondrium can improve graft viability and biomechanical properties.

LEVEL OF EVIDENCE

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266.

Auricle shaping using 3D printing and autologous diced cartilage

OBJECTIVE

To reconstruct the auricle using a porous, hollow, three-dimensional (3D)-printed mold and autologous diced cartilage mixed with platelet-rich plasma (PRP).

METHODS

Materialise Magics v20.03 was used to design a 3D, porous, hollow auricle mold. Ten molds were printed by selective laser sintering with polyamide. Cartilage grafts were harvested from one ear of a New Zealand rabbit, and PRP was prepared using 10 mL of auricular blood from the same animal. Ear cartilage was diced into 0.5- to 2.0-mm pieces, weighed, mixed with PRP, and then placed inside the hollow mold. Composite grafts were then implanted into the backs of respective rabbits (n = 10) for 4 months. The shape and composition of the diced cartilage were assessed histologically, and biomechanical testing was used to determine stiffness.

RESULTS

The 3D-printed auricle molds were 0.6-mm thick and showed connectivity between the internal and external surfaces, with round pores of 0.1 to 0.3 cm. After 4 months, the diced cartilage pieces had fused into an auricular shape with high fidelity to the anthropotomy. The weight of the diced cartilage was 5.157 ± 0.230 g (P > 0.05, compared with preoperative). Histological staining showed high chondrocyte viability and the production of collagen II, glycosaminoglycans, and other cartilaginous matrix components. In unrestricted compression tests, auricle stiffness was 0.158 ± 0.187 N/mm, similar to that in humans.

CONCLUSION

Auricle grafts were constructed successfully through packing a 3D-printed, porous, hollow auricle mold with diced cartilage mixed with PRP. The auricle cartilage contained viable chondrocytes, appropriate extracellular matrix components, and good mechanical properties.

LEVELS OF EVIDENCE

NA. Laryngoscope, 129:2467-2474, 2019.