&NA; This study evaluates the feasibility of growing tissue‐engineered cartilage in the shape of a human ear using chondrocytes seeded onto a synthetic biodegradable polymer fashioned in the shape of a 3‐year‐old child's auricle. A polymer template was formed in the shape of a human auricle using a nonwoven mesh of polyglycolic acid molded after being immersed in a 1% solution of polylactic acid. Each polyglycolic acid‐polylactic acid template was seeded with chondrocytes isolated from bovine articular cartilage and then implanted into subcutaneous pockets on the dorsa of 10 athymic mice. The three‐dimensional structure was well maintained after removal of an external stent that had been applied for 4 weeks. Specimens harvested 12 weeks after implantation and subjected to gross morphologic and histologic analysis demonstrated new cartilage formation. The overall geometry of the experimental specimens closely resembled the complex structure of the child's auricle. These findings demonstrate that polyglycolic acid‐polylactic acid constructs can be fabricated in a very intricate configuration and seeded with chondrocytes to generate new cartilage that would be useful in plastic and reconstructive surgery. (Plast. Reconstr. Surg. 100: 297, 1997.)

Transplantation of chondrocytes utilizing a polymer-cell construct to produce tissue-engineered cartilage in the shape of a human ear

During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Three-dimensional (3D) printing refers to a number of manufacturing technologies that generate a physical model from digital information. Medical 3D printing was once an ambitious pipe dream. However, time and investment made it real. Nowadays, the 3D printing technology represents a big opportunity to help pharmaceutical and medical companies to create more specific drugs, enabling a rapid production of medical implants, and changing the way that doctors and surgeons plan procedures. Patient-specific 3D-printed anatomical models are becoming increasingly useful tools in today's practice of precision medicine and for personalized treatments. In the future, 3D-printed implantable organs will probably be available, reducing the waiting lists and increasing the number of lives saved. Additive manufacturing for healthcare is still very much a work in progress, but it is already applied in many different ways in medical field that, already reeling under immense pressure with regards to optimal performance and reduced costs, will stand to gain unprecedented benefits from this good-as-gold technology. The goal of this analysis is to demonstrate by a deep research of the 3D-printing applications in medical field the usefulness and drawbacks and how powerful technology it is.

/pdf/the-role-of-3d-printing-in-medical-applications-a-state-of-2diagvr4s5.pdf

The Role of 3D Printing in Medical Applications: A State of the Art

Microtia is a congenital anomaly of the ear that ranges in severity from mild structural abnormalities to complete absence of the ear, and can occur as an isolated birth defect or as part of a spectrum of anomalies or a syndrome. Microtia is often associated with hearing loss and patients typically require treatment for hearing impairment and surgical ear reconstruction. The reported prevalence varies among regions, from 0.83 to 17.4 per 10,000 births and the prevalence is considered to be higher in Hispanics, Asians, Native Americans, and Andeans. The etiology of microtia and the cause of this wide variability in prevalence are poorly understood. Strong evidence supports the role of environmental and genetic causes for microtia. Although some studies have identified candidate genetic variants for microtia, no causal genetic mutation has been confirmed. The application of novel strategies in developmental biology and genetics has facilitated elucidation of mechanisms controlling craniofacial development. In this paper we review current knowledge of the epidemiology and genetics of microtia, including potential candidate genes supported by evidence from human syndromes and animal models. We also discuss the possible etiopathogenesis in light of the hypotheses formulated to date: neural crest cells disturbance, vascular disruption and altitude.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ajmg.a.34352

Microtia: Epidemiology and genetics

Skeletal muscle tissue engineering (SMTE) aims at repairing defective skeletal muscles. Until now, numerous developments are made in SMTE; however, it is still challenging to recapitulate the complexity of muscles with current methods of fabrication. Here, after a brief description of the anatomy of skeletal muscle and a short state-of-the-art on developments made in SMTE with "conventional methods," the use of 3D bioprinting as a new tool for SMTE is in focus. The current bioprinting methods are discussed, and an overview of the bioink formulations and properties used in 3D bioprinting is provided. Finally, different advances made in SMTE by 3D bioprinting are highlighted, and future needs and a short perspective are provided.

/pdf/3d-bioprinting-in-skeletal-muscle-tissue-engineering-lhrfhk6mcn.pdf

3D Bioprinting in Skeletal Muscle Tissue Engineering.

In Vitro Regeneration of Patient-specific Ear-shaped Cartilage and Its First Clinical Application for Auricular Reconstruction.

Summary Objective To investigate relative indications for three different surgical techniques used in total ear reconstruction. Methods A total of 1864 cases requiring complete ear reconstruction were performed. In 1485 cases reconstruction was effected by skin expansion and subsequent grafting of autogenous rib cartilage frameworks. In 355 cases skin expansion was followed by insertion of a Medpor ® framework. Twenty-four cases were repaired with titanium dowel retained prosthesis. Clinical results of these three surgical techniques were evaluated. Results All three methods were successfully used in total ear reconstruction and showed a satisfactory appearance. For patients less than 30 years old and with intact mastoid skin, the rib cartilage grafting methods were preferred. A Medpor ® framework was suitable for cases over 30 years old, despite the appearance of mild inflammation in the skin flap. We resorted to a prosthetic reconstruction in patients whose mastoid skin was seriously damaged when they were unwilling to accept more complex methods of ear reconstruction. Conclusions The three methods described provide satisfactory clinical results and are each indicated for specific patient cohorts.

https://www.jprasurg.com/article/S1748-6815(08)00792-4/pdf

Clinical evaluation of three total ear reconstruction methods

Summary Background During microtia reconstruction, the intraoperative design of the cartilage framework is important for the appearance and symmetry of the bilateral auricles. Templates (traditionally, the X-ray film template) are usually utilized to complete the task, which can provide cues regarding size, cranioauricular angle and positioning to the surgeons. With a combination of three-dimensional (3D) scanning and additive manufacturing (AM) techniques, we utilized two different ear-shaped templates (sheet moulding and 3D templates) during the fabrication of 3D-customized autologous cartilage frameworks for auricle reconstruction. Methods Forty unilateral microtia patients were included in the study. All the patients underwent auricle reconstruction using the tissue-expanding technique assisted by the new AM templates. Images were processed using computer-aided design software and exported to print two different AM ear-shaped templates: sheet moulding and 3D. Both templates were assisted by the 3D framework fabrication. The 3D images of each patient's head were captured preoperatively using a 3D scanner. X-ray film templates were also made for the patients. The lengths and widths of the contralateral auricles, X-ray film and sheet moulding templates were measured in triplicate. The error of the template and the contralateral auricle were used to compare the accuracy between the two templates. Results Between January and May 2014, 40 unilateral microtia patients aged 6–29 years were included in this study. All patients underwent auricle reconstruction using autogenous costal cartilage. The sterilized AM templates were used to assist in the framework fabrication. The operative time was decreased by an average of 15 min compared with the method assisted by the X-ray film template. Postoperative appearance evaluation (based on five indexes: symmetry, length, width, cranioauricular angle and the substructure of the reconstructed ear) was performed by both the doctors and the patients (or their parents). Follow-up (ranging from 9 to 18 months) showed that all of the patients obtained satisfactory results with life-like 3D configuration and symmetric cranioauricular angle. The follow-up showed that no surgery-related complications occurred. Comparing the accuracy of the X-ray film and sheet moulding templates, the average errors of length were 1.8 mm ± 1.44 mm and 0.39 mm ± 0.35 mm, respectively, and the average width errors were 1.32 mm ± 0.88 mm and 0.3 mm ± 0.47 mm, respectively. The new sheet moulding template was more accurate than the X-ray template. Conclusions The new sheet-moulding template is much more accurate than the traditional X-ray film template. Framework fabrication assisted by accurate 3D and informative AM templates contributed to individualized cartilage framework fabrication and satisfactory results.

Three-dimensional autologous cartilage framework fabrication assisted by new additive manufactured ear-shaped templates for microtia reconstruction

OBJECTIVE To explore surgical procedure of congenital microtia METHODS Ear reconstruction was made using soft tissue skin expander and autogenous rib cartilage framework RESULTS Long time follow-up showed that the flap of reconstructed ear was ruddy, soft, with normal sensory function; cartilage framework had no degeneration, absorption and deformation In addition, the reconstructed ears were coincidence with the normal side on location, form and dimension CONCLUSIONS It was a good method for congenital microtia to use soft tissue skin expander together with autogenous rib cartilage framework at present time

Ear reconstruction using soft tissue expander in the treatment of congenital microtia

Summary Background Polyotia is an extremely rare type of congenital external ear malformation, which is defined as an accessory ear that is large enough to resemble an additional pinna. The terms 'mirror ear' or 'accessory ear' are sometime used. We present our methods in correcting this malformation and summarise the aetiology. Methods The posterior part of the polyotia may presents with a normal ear, a constricted ear or a microtic ear. Free auricular composite tissue transplantation was used to correct the constricted ear. Ear reconstruction was applied in cases of microtia. The anterior auricle was mainly used to form the tragus. Results 7 cases polyotia were treated between 2004 and 2008. After free auricular composite tissue transplantation the size of the constricted ear and the contralateral ear was similar. In microtia cases the reconstructed ears were natural looking and had a satisfactory three-dimensional contour. The extra tissue of the anterior ear was excised and the tragus was reconstructed. Conclusions Through operative intervention tailored to the individual case natural-looking and symmetric ears were acquired. The aetiology of polyotia probably relates to abnormal migration of neural crest cell.

https://www.jprasurg.com/article/S1748-6815(09)00503-8/pdf

Bo Pan

Papers

In Vitro Regeneration of Patient-specific Ear-shaped Cartilage and Its First Clinical Application for Auricular Reconstruction.

Clinical evaluation of three total ear reconstruction methods

Three-dimensional autologous cartilage framework fabrication assisted by new additive manufactured ear-shaped templates for microtia reconstruction

Ear reconstruction using soft tissue expander in the treatment of congenital microtia

Surgical management of polyotia.