Engineering cartilage tissues with the shape of human nasal alar by using chondrocyte macroaggregate--Experiment study in rabbit model

Cartilage Tissue Engineering for Nasal Alar and Auricular Reconstruction: A Critical Review of the Literature and Implications for Practice in Dermatologic Surgery

BACKGROUND

Reconstructing defects requiring replacement of nasal or auricular cartilage after Mohs micrographic surgery can at times be challenging. While autologous cartilage grafting is considered the mainstay for repair, it may be limited by cartilage quality/quantity, donor site availability/morbidity, and surgical complications. Tissue-engineered cartilage has recently shown promise for repairing properly selected facial defects.

OBJECTIVE

To (1) provide a comprehensive overview of the literature on the use of tissue-engineered cartilage for nasal alar and auricular defects, and (2) discuss this technology's advantages and future implications for dermatologic surgery.

MATERIALS AND METHODS

A literature search was performed using PubMed/MEDLINE and Google Scholar databases. Studies discussing nasal alar or auricular cartilage tissue engineering were included.

RESULTS

Twenty-seven studies were included. Using minimal donor tissue, tissue-engineered cartilage can create patient-specific, three-dimensional constructs that are biomechanically and histologically similar to human cartilage. The constructs maintain their shape and structural integrity after implantation into animal and human models.

CONCLUSION

Tissue-engineered cartilage may be able to replace native cartilage in reconstructing nasal alar and auricular defects given its ability to overcome several limitations of autologous cartilage grafting. Although further research is necessary, dermatologic surgeons should be aware of this innovative technique and its future implications.

[Scanning electron microscope of the human nasal septum]

Objective:Explore the significance of ultrastructural differences in tissue engineering, 3D printing, and rhinoplasty. Methods: 32 specimens （8 vomers, 8 perpendicular plates of ethmoid bone, 8 maxillary nasal crests, and 8 septal cartilage） of the nasal septum from patients with a nasal deviated septum and chronic sinusitis undergoing septoplasty were selected and examined using scanning electron microscopy. Results: The nasal septum of patients of different ages behaves similarly under the scanning electron microscope, and the bones of different parts of the nasal septum have similarities and differences. Conclusion:By observing the scanning electron micrograph of the nasal septum and analyzing the surface ultrastructure, it provides important information for the development of tissue engineering, assists in the refined modeling of 3D printing technology, and provides more ideal restoration materials for clinical operations.

Will Tissue-Engineering Strategies Bring New Hope for the Reconstruction of Nasal Septal Cartilage?

The nasal septal cartilage plays an important role in the growth of midface and as a vertical strut preventing the collapse of the nasal bones. The repair of nasal cartilage defects remains a major challenge in reconstructive surgery. The tissue engineering strategy in the development of tissue has opened a new perspective to generate functional tissue for transplantation. Given the poor regenerative properties of cartilage and a limited amount of autologous cartilage availability, intense interest has evoked for tissue engineering approaches for cartilage development to provide better outcomes for patients who require nasal septal reconstruction. Despite numerous attempts to substitute the shapely hyaline cartilage in the nasal cartilages, many significant challenges remained unanswered. The aim of this research was to carry out a critical review of the literature on research work carried out on the development of septal cartilage using a tissue engineering approach, concerning different cell sources, scaffolds and growth factors, as well as its clinical pathway and trials have already been carried out.

Model to Estimate Threshold Mechanical Stability of Lower Lateral Cartilage

IMPORTANCE

In rhinoplasty, techniques used to alter the shape of the nasal tip often compromise the structural stability of the cartilage framework in the nose. Determining the minimum threshold level of cartilage stiffness required to maintain long-term structural stability is a critical aspect in performing these surgical maneuvers.

OBJECTIVE

To quantify the minimum threshold mechanical stability (elastic modulus) of lower lateral cartilage (LLC) according to expert opinion.

METHODS

Five anatomically correct LLC phantoms were made from urethane via a 3-dimensional computer modeling and injection molding process. All 5 had identical geometry but varied in stiffness along the intermediate crural region (0.63-30.6 MPa).

DESIGN, SETTING, AND PARTICIPANTS

A focus group of experienced rhinoplasty surgeons (n = 33) was surveyed at a regional professional meeting on October 25, 2013. Each survey participant was presented the 5 phantoms in a random order and asked to arrange the phantoms in order of increasing stiffness based on their sense of touch. Then, they were asked to select a single phantom out of the set that they believed to have the minimum acceptable mechanical stability for LLC to maintain proper form and function.

MAIN OUTCOMES AND MEASURES

A binary logistic regression was performed to calculate the probability of mechanical acceptability as a function of the elastic modulus of the LLC based on survey data. A Hosmer-Lemeshow test was performed to measure the goodness of fit between the logistic regression and survey data. The minimum threshold mechanical stability for LLC was taken at a 50% acceptability rating.

RESULTS

Phantom 4 was selected most frequently by the participants as having the minimum acceptable stiffness for LLC intermediate care. The minimum threshold mechanical stability for LLC was determined to be 3.65 MPa. The Hosmer-Lemeshow test revealed good fit between the logistic regression and survey data (χ23 = 0.92, P = .82).

CONCLUSIONS AND RELEVANCE

This study presents a novel method of modeling anatomical structures and quantifying the mechanical properties of nasal cartilage. Quantifying these parameters is an important step in guiding surgical maneuvers performed in rhinoplasty.

LEVEL OF EVIDENCE

5.

Prefabricated, ear-shaped cartilage tissue engineering by scaffold-free porcine chondrocyte membrane

BACKGROUND

Ear defects caused by traumatic injury, tumor ablation, and congenital deficiency are still challenging problems for the plastic and reconstructive surgeon. The authors developed a scaffold-free, ear-shaped cartilage by tailoring a multilayered chondrocyte membrane on an ear-shaped titanium alloy model and investigated the possibility of long-term ear-shaped maintenance in nude mice.

METHODS

High-density chondrocytes (approximately 30 × 10 cells) were seeded to produce chondrocyte membranes after cultivation under chondrogenic medium for 2 weeks. Then, three-layer chondrocyte membranes were tailored on the ear-shaped titanium mold and fixed by 6-0 nylon. The constructs were implanted onto the dorsal pockets of nude mice for 8 and 24 weeks. The chondrocyte membrane, 8- and 24-week implants were analyzed by safranin O, toluidine blue, elastica van Gieson, and collagen type II immunohistochemistry stains and quantitative measurement of glycosaminoglycan and total collagen compared with native cartilage. Mechanical strength was compared by compressive Young's modulus.

RESULTS

Results showed that the chondrocyte membrane was durable and nonfragile and easily manipulated by forceps. The composite of chondrocyte membrane and titanium alloy maintained the stable ear-like shape after 8 and 24 weeks of subcutaneous implantation. Histologic examination verified that the newly formed tissue at the implant construct was elastic cartilage at both 8 and 24 weeks by safranin O, toluidine blue, elastica van Gieson, and collagen type II immunohistochemistry stains. The Young's modulus was only half of and similar to normal cartilage in 8- and 24-week implants, respectively.

CONCLUSION

This study demonstrated that an ear-shaped elastic cartilage could be regenerated by a scaffold-free chondrocyte membrane shaped by a prefabricated, three-dimensional, ear-shaped titanium mold.

Tissue engineering of human nasal alar cartilage precisely by using three-dimensional printing

BACKGROUND

Tissue engineering strategies hold promise for the restoration of damaged cartilage. However, the results of most studies report irregularly shaped beads of cartilage, which are not precise enough. Thus, a precise shape of cartilage graft must be taken into consideration. The goal of this study was to develop a simple method of creating a precisely predetermined nasal alar shape with the aid of three-dimensional printing.

METHODS

Lower lateral cartilage from cadavers was observed and scanned by computed tomography. Molds of the lower lateral cartilage were achieved by using three-dimensional printing. Human nasal cartilage was obtained and chondrocytes were harvested. Then, the mixture of cells and poly(glycolic acid)/poly-L-lactic acid was cultured in vitro and implanted into the subcutaneous tissue of nude mice.

RESULTS

After subcutaneous implantation, the length and width of the samples were measured, and the results were not statistically significantly different from the native lower lateral cartilage (p > 0.05). Their thickness was measured and the results were statistically different from the native lower lateral cartilage (p < 0.05). Histologic examination of the engineered constructs revealed that both the cell and tissue morphologic features of engineered cartilage were similar to those of native lower lateral cartilage. The biomechanical properties of the engineered cartilage exceeded those of native cartilage.

CONCLUSIONS

This study demonstrates that three-dimensional printing-aided tissue engineering can achieve precise three-dimensional shapes of human nasal alar cartilage. To our knowledge, this is the first reported creation of a precise nasal alar cartilage with a tissue-engineering strategy and three-dimensional printing technique.

Cell bricks-enriched platelet-rich plasma gel for injectable cartilage engineering - an in vivo experiment in nude mice

Clinical application of platelet-rich plasma (PRP)-based injectable tissue engineering is limited by weak mechanical properties and a rapid fibrinolytic rate. We proposed a new strategy, a cell bricks-stabilized PRP injectable system, to engineer and regenerate cartilage with stable morphology and structure in vivo. Chondrocytes from the auricular cartilage of rabbits were isolated and cultured to form cell bricks (fragmented cell sheet) or cell expansions. Fifteen nude mice were divided evenly (n = 5) into cells-PRP (C-P), cell bricks-PRP (CB-P) and cell bricks-cells-PRP (CB-C-P) groups. Cells, cell bricks or a cell bricks/cells mixture were suspended in PRP and were injected subcutaneously in animals. After 8 weeks, all the constructs were replaced by white resilient tissue; however, specimens from the CB-P and CB-C-P groups were well maintained in shape, while the C-P group appeared distorted, with a compressed outline. Histologically, all groups presented lacuna-like structures, glycosaminoglycan-enriched matrices and positive immunostaining of collagen type II. Different from the uniform structure presented in CB-C-P samples, CB-P presented interrupted, island-like chondrogenesis and contracted structure; fibrous interruption was shown in the C-P group. The highest percentage of matrix was presented in CB-C-P samples. Collagen and sGAG quantification confirmed that the CB-C-P constructs had statistically higher amounts than the C-P and CB-P groups; statistical differences were also found among the groups in terms of biomechanical properties and gene expression. We concluded that cell bricks-enriched PRP gel sufficiently enhanced the morphological stability of the constructs, maintained chondrocyte phenotypes and favoured chondrogenesis in vivo, which suggests that such an injectable, completely biological system is a suitable cell carrier for cell-based cartilage repair.

Model for estimating the threshold mechanical stability of structural cartilage grafts used in rhinoplasty

OBJECTIVES/HYPOTHESIS

Characterizing the mechanical properties of structural cartilage grafts used in rhinoplasty is valuable because softer engineered tissues are more time- and cost-efficient to manufacture. The aim of this study is to quantitatively identify the threshold mechanical stability (e.g., Young's modulus) of columellar, L-strut, and alar cartilage replacement grafts.

STUDY DESIGN

Descriptive, focus group survey.

METHODS

Ten mechanical phantoms of identical size (5 x 20 x 2.3 mm) and varying stiffness (0.360 to 0.85 MPa in 0.05 MPa increments) were made from urethane. A focus group of experienced rhinoplasty surgeons (n = 25, 5 to 30 years in practice) were asked to arrange the phantoms in order of increasing stiffness. Then, they were asked to identify the minimum acceptable stiffness that would still result in favorable surgical outcomes for three clinical applications: columellar, L-strut, and lateral crural replacement grafts. Available surgeons were tested again after 1 week to evaluate intra-rater consistency.

RESULTS

For each surgeon, the threshold stiffness for each clinical application differed from the threshold values derived by logistic regression by no more than 0.05 MPa (accuracy to within 10%). Specific thresholds were 0.56, 0.59, and 0.49 MPa for columellar, L-strut, and alar grafts, respectively. For comparison, human nasal septal cartilage is approximately 0.8 MPa.

CONCLUSIONS

There was little inter- and intra-rater variation of the identified threshold values for adequate graft stiffness. The identified threshold values will be useful for the design of tissue-engineered or semisynthetic cartilage grafts for use in structural nasal surgery.

Novel approach to engineer implantable nasal alar cartilage employing marrow precursor cell sheet and biodegradable scaffold

PURPOSE

Repair of nasal and auricular malformation remains an obstacle for clinicians because of poor regenerative capacity of cartilage and limitation of donor sites. In the current study, we developed a novel approach to regenerate implantable nasal alar cartilage by using marrow precursor cell (MPC) sheet and biodegradable scaffold of polylactic acid-polyglycolic acid copolymer (PLGA).

MATERIALS AND METHODS

Rabbit MPCs were expanded and induced by transforming growth factor-beta to improve chondrocyte phenotype. MPC sheets were obtained by continuous culture and used to wrap PLGA scaffold in the shape of the human nasal alar. The constructs were incubated in a spinner flask for 4 weeks, and cartilage formation was investigated by gross inspection and histological examination. The constructs were then implanted subcutaneously into a nude mouse. Specimens were harvested and analyzed 4 weeks after implantation.

RESULTS

The results showed that cartilaginous tissue formed and PLGA absorbed during in vitro incubation. Histological analysis showed engineered cartilage consisted of evenly spaced lacunae embedded in a matrix rich in proteoglycans, and kept the initial shape of the nasal alar. Based on this "MPC sheet combining polymer strategy," implantable nasal alar could be successfully regenerated.

CONCLUSION

This strategy has the advantage of high cell transplantation efficiency and great potential for clinical application.

Vitalisation of tubular coral scaffolds with cell sheets for regeneration of long bones: a preliminary study in nude mice

In this study, cell sheets comprising multilayered living bone marrow stromal cells and extracellular matrix were assembled with tubular coral scaffolds for long bone regeneration. Cell sheet with visible mineralized nodules was harvested and wrapped against tubular coral scaffolds with 5mm diameter and 1.5mm wall thickness. New bone formation was investigated by CT scan and histological observation 8 and 12 weeks after implantation of cell sheet/scaffold. The results showed that cortical bone formed within the constructs for both groups. New bone composed 25.75% of the graft in 8 weeks group, compared to that of 40.01% in 12 weeks group. Histological examination showed that new bone formation was in the manner of endochondral osteogenesis, with woven bone matrix subsequently maturing into fully mineralized compact bone. These findings demonstrated that osteogenic cell sheet could vitalize tubulate coral scaffolds to regenerate bone graft with similar shape and structure to native bone.