Bioresorbable airway splint created with a three-dimensional printer

Preparation and Stability Study of an Injectable Hydrogel for Artificial Intraocular Lenses

Currently available intraocular lenses (IOLs) on the market often differ significantly in elastic modulus compared to the natural human lens, which impairs their ability to respond effectively to the tension of the ciliary muscles for focal adjustment after implantation. In this study, we synthesized a polyacrylamide-sodium acrylate hydrogel (PAH) through the cross-linking polymerization of acrylamide and sodium acrylate. This hydrogel possesses excellent biocompatibility and exhibits several favorable properties. Notably, the hydrogel demonstrates high transparency (94%) and a refractive index (1.41 ± 0.07) that closely matches that of the human lens (1.42). Additionally, it shows strong compressive strength (14.00 kPa), good extensibility (1400%), and an appropriate swelling ratio (50 ± 2.5%). Crucially, the tensile modulus of the hydrogel is 2.07 kPa, which closely aligns with the elastic modulus of the human lens (1.70-2.10 kPa), enabling continuous focal adjustment under the tension exerted by the ciliary muscles.

Patient, parent and professional expert perspectives on personalized regenerative implants: a qualitative focus group study

Background: Perspectives of patients, parents and professional experts on personalized regenerative implants for regenerative medicine purposes are largely unknown.Method: To better understand these perspectives, we conducted four focus groups with professional experts of mixed European nationality (n = 8), Dutch patients with regular implants (n = 8), Dutch and Belgian (n = 5) and Spanish (n = 8) parents of children with cleft palate.Results: Two overarching themes were identified: 'patient-centered research and care' and 'ambivalent attitudes toward personalized regenerative implants'.Discussion: The results reveal that stakeholders should adopt a participatory rather than an impairment discourse and address the ambivalence among professional experts, patients and parents.Conclusion: Considering stakeholder perspectives facilitates ethical and responsible development and use of personalized regenerative implants.

Challenges and Opportunities in Developing Tracheal Substitutes for the Recovery of Long-Segment Defects

Tracheal resection and reconstruction procedures are necessary when stenosis, tracheomalacia, tumors, vascular lesions, or tracheal injury cause a tracheal blockage. Replacement with a tracheal substitute is often recommended when the trauma exceeds 50% of the total length of the trachea in adults and 30% in children. Recently, tissue engineering and other advanced techniques have shown promise in fabricating biocompatible tracheal substitutes with physical, morphological, biomechanical, and biological characteristics similar to native trachea. Different polymers and biometals are explored. Even with limited success with tissue-engineered grafts in clinical settings, complete healing of tracheal defects remains a substantial challenge due to low mechanical strength and durability of the graft materials, inadequate re-epithelialization and vascularization, and restenosis. This review has covered a range of reconstructive and regenerative techniques, design criteria, the use of bioprostheses and synthetic grafts for the recovery of tracheal defects, as well as the traditional and cutting-edge methods of their fabrication, surface modification for increased immuno- or biocompatibility, and associated challenges.

Tissue-engineered tracheal implants: Advancements, challenges, and clinical considerations

Restoration of extensive tracheal damage remains a significant challenge in respiratory medicine, particularly in instances stemming from conditions like infection, congenital anomalies, or stenosis. The trachea, an essential element of the lower respiratory tract, constitutes a fibrocartilaginous tube spanning approximately 10-12 cm in length. It is characterized by 18 ± 2 tracheal cartilages distributed anterolaterally with the dynamic trachealis muscle located posteriorly. While tracheotomy is a common approach for patients with short-length defects, situations requiring replacement arise when the extent of lesion exceeds 1/2 of the length in adults (or 1/3 in children). Tissue engineering (TE) holds promise in developing biocompatible airway grafts for addressing challenges in tracheal regeneration. Despite the potential, the extensive clinical application of tissue-engineered tracheal substitutes encounters obstacles, including insufficient revascularization, inadequate re-epithelialization, suboptimal mechanical properties, and insufficient durability. These limitations have led to limited success in implementing tissue-engineered tracheal implants in clinical settings. This review provides a comprehensive exploration of historical attempts and lessons learned in the field of tracheal TE, contextualizing the clinical prerequisites and vital criteria for effective tracheal grafts. The manufacturing approaches employed in TE, along with the clinical application of both tissue-engineered and non-tissue-engineered approaches for tracheal reconstruction, are discussed in detail. By offering a holistic view on TE substitutes and their implications for the clinical management of long-segment tracheal lesions, this review aims to contribute to the understanding and advancement of strategies in this critical area of respiratory medicine.

3D printing modality effect: Distinct printing outcomes dependent on selective laser sintering (SLS) and melt extrusion

A direct and comprehensive comparative study on different 3D printing modalities was performed. We employed two representative 3D printing modalities, laser- and extrusion-based, which are currently used to produce patient-specific medical implants for clinical translation, to assess how these two different 3D printing modalities affect printing outcomes. The same solid and porous constructs were created from the same biomaterial, a blend of 96% poly-ε-caprolactone (PCL) and 4% hydroxyapatite (HA), using two different 3D printing modalities. Constructs were analyzed to assess their printing characteristics, including morphological, mechanical, and biological properties. We also performed an in vitro accelerated degradation study to compare their degradation behaviors. Despite the same input material, the 3D constructs created from different 3D printing modalities showed distinct differences in morphology, surface roughness and internal void fraction, which resulted in different mechanical properties and cell responses. In addition, the constructs exhibited different degradation rates depending on the 3D printing modalities. Given that each 3D printing modality has inherent characteristics that impact printing outcomes and ultimately implant performance, understanding the characteristics is crucial in selecting the 3D printing modality to create reliable biomedical implants.

Advancing cardiac regeneration through 3D bioprinting: methods, applications, and future directions

Cardiovascular diseases (CVDs) represent a paramount global mortality concern, and their prevalence is on a relentless ascent. Despite the effectiveness of contemporary medical interventions in mitigating CVD-related fatality rates and complications, their efficacy remains curtailed by an array of limitations. These include the suboptimal efficiency of direct cell injection and an inherent disequilibrium between the demand and availability of heart transplantations. Consequently, the imperative to formulate innovative strategies for cardiac regeneration therapy becomes unmistakable. Within this context, 3D bioprinting technology emerges as a vanguard contender, occupying a pivotal niche in the realm of tissue engineering and regenerative medicine. This state-of-the-art methodology holds the potential to fabricate intricate heart tissues endowed with multifaceted structures and functionalities, thereby engendering substantial promise. By harnessing the prowess of 3D bioprinting, it becomes plausible to synthesize functional cardiac architectures seamlessly enmeshed with the host tissue, affording a viable avenue for the restitution of infarcted domains and, by extension, mitigating the onerous yoke of CVDs. In this review, we encapsulate the myriad applications of 3D bioprinting technology in the domain of heart tissue regeneration. Furthermore, we usher in the latest advancements in printing methodologies and bioinks, culminating in an exploration of the extant challenges and the vista of possibilities inherent to a diverse array of approaches.

Recent development and future application of biodegradable ureteral stents

Ureteral stenting is a common clinical procedure for the treatment of upper urinary tract disorders, including conditions such as urinary tract infections, tumors, stones, and inflammation. Maintaining normal renal function by preventing and treating ureteral obstruction is the primary goal of this procedure. However, the use of ureteral stents is associated with adverse effects, including surface crusting, bacterial adhesion, and lower urinary tract symptoms (LUTS) after implantation. Recognizing the need to reduce the complications associated with permanent ureteral stent placement, there is a growing interest among both physicians and patients in the use of biodegradable ureteral stents (BUS). The evolution of stent materials and the exploration of different stent coatings have given these devices different roles tailored to different clinical needs, including anticolithic, antibacterial, antitumor, antinociceptive, and others. This review examines recent advances in BUS within the last 5 years, providing an in-depth analysis of their characteristics and performance. In addition, we present prospective insights into the future applications of BUS in clinical settings.

Management Strategies for Congenital Heart Disease Comorbid with Airway Anomalies in Children

OBJECTIVE

To assess management strategies for pediatric patients with the challenging combination of congenital heart diseases (CHDs) and airway anomalies.

STUDY DESIGN

Patients diagnosed with CHD and airway anomalies in the Pediatric Cardiac Surgery Centre of Fuwai Hospital from January 2016 to December 2020 were included in this retrospective study. Patients were divided into three groups based on different management, including the conservative group, the slide group (slide tracheoplasty), and the suspension group (suspension with external stenting). Patients' data and computed tomography measurements from medical records were reviewed.

RESULTS

A total of 139 patients were included in the cohort; 107 had conservative airway treatment (conservative group), 15 had slide tracheoplasty (slide group), and 17 had tracheal suspension operation (suspension group). The top three associated intracardiac anomalies were ventricular septal defect (n = 34, 24%), pulmonary artery sling (n = 22, 16%), and tetralogy of Fallot (n = 15, 11%). Compared with patients with conservative airway management (100 minutes [median], 62-152 [IQR]), the extra airway procedure prolonged cardiopulmonary bypass duration, with 202 minutes (IQR, 119-220) for the slide group and 150 minutes (IQR, 125-161) for the suspension group. Patients who underwent slide tracheoplasty required prolonged mechanical ventilation (129 minutes [median], 56-328 [IQR]). Of the total cohort, 6 in-hospital deaths, all in the conservative group, and 8 mid-to long-term deaths, with 6 in the conservative group, occurred.

CONCLUSIONS

Both conservative and surgical management of CHD patients with airway anomalies have promising outcomes. Extra tracheobronchial procedures, especially the slide tracheoplasty, significantly prolonged cardiopulmonary bypass duration. Based on multidisciplinary team assessment, individualized management strategies should be developed for these patients.

Personalized 3D printed scaffolds: The ethical aspects

Personalized 3D printed scaffolds are a new generation of implants for tissue engineering and regenerative medicine purposes. Scaffolds support cell growth, providing an artificial extracellular matrix for tissue repair and regeneration and can biodegrade once cells have assumed their physiological and structural roles. The ethical challenges and opportunities of these implants should be mapped in parallel with the life cycle of the scaffold to assist their development and implementation in a responsible, safe, and ethically sound manner. This article provides an overview of these relevant ethical aspects. We identified nine themes which were linked to three stages of the life cycle of the scaffold: the development process, clinical testing, and the implementation process. The described ethical issues are related to good research and clinical practices, such as privacy issues concerning digitalization, first-in-human trials, responsibility and commercialization. At the same time, this article also creates awareness for underexplored ethical issues, such as irreversibility, embodiment and the ontological status of these scaffolds. Moreover, it exemplifies how to include gender in the ethical assessment of new technologies. These issues are important for responsible development and implementation of personalized 3D printed scaffolds and in need of more attention within the additive manufacturing and tissue engineering field. Moreover, the insights of this review reveal unresolved qualitative empirical and normative questions that could further deepen the understanding and co-creation of the ethical implications of this new generation of implants.

Surgical Innovations in Tracheal Reconstruction: A Review on Synthetic Material Fabrication

Background and Objectives: The aim of this review is to explore the recent surgical innovations in tracheal reconstruction by evaluating the uses of synthetic material fabrication when dealing with tracheomalacia or stenotic pathologies, then discussing the challenges holding back these innovations. Materials and Methods: A targeted non-systematic review of published literature relating to tracheal reconstruction was performed within the PubMed database to help identify how synthetic materials are utilised to innovate tracheal reconstruction. Results: The advancements in 3D printing to aid synthetic material fabrication have unveiled promising alternatives to conventional approaches. Achieving successful tracheal reconstruction through this technology demands that the 3D models exhibit biocompatibility with neighbouring tracheal elements by encompassing vasculature, chondral foundation, and immunocompatibility. Tracheal reconstruction has employed grafts and scaffolds, showing a promising beginning in vivo. Concurrently, the integration of resorbable models and stem cell therapy serves to underscore their viability and application in the context of tracheal pathologies. Despite this, certain barriers hinder its advancement in surgery. The intricate tracheal structure has posed a challenge for researchers seeking novel approaches to support its growth and regeneration. Conclusions: The potential of synthetic material fabrication has shown promising outcomes in initial studies involving smaller animals. Yet, to fully realise the applicability of these innovative developments, research must progress toward clinical trials. These trials would ascertain the anatomical and physiological effects on the human body, enabling a thorough evaluation of post-operative outcomes and any potential complications linked to the materials or cells implanted in the trachea.

Synergistic Effect of Physical and Chemical Cross-Linkers Enhances Shape Fidelity and Mechanical Properties of 3D Printable Low-Modulus Polyesters

Three-dimensional (3D) printing is becoming increasingly prevalent in tissue engineering, driving the demand for low-modulus, high-performance, biodegradable, and biocompatible polymers. Extrusion-based direct-write (EDW) 3D printing enables printing and customization of low-modulus materials, ranging from cell-free printing to cell-laden bioinks that closely resemble natural tissue. While EDW holds promise, the requirement for soft materials with excellent printability and shape fidelity postprinting remains unmet. The development of new synthetic materials for 3D printing applications has been relatively slow, and only a small polymer library is available for tissue engineering applications. Furthermore, most of these polymers require high temperature (FDM) or additives and solvents (DLP/SLA) to enable printability. In this study, we present low-modulus 3D printable polyester inks that enable low-temperature printing without the need for solvents or additives. To maintain shape fidelity, we incorporate physical and chemical cross-linkers. These 3D printable polyester inks contain pendant amide groups as the physical cross-linker and coumarin pendant groups as the photochemical cross-linker. Molecular dynamics simulations further confirm the presence of physical interactions between different pendants, including hydrogen bonding and hydrophobic interactions. The combination of the two types of cross-linkers enhances the zero-shear viscosity and hence provides good printability and shape fidelity.

Assessment of Staphylococcus Aureus growth on biocompatible 3D printed materials

The customizability of 3D printing allows for the manufacturing of personalized medical devices such as laryngectomy tubes, but it is vital to establish the biocompatibility of printing materials to ensure that they are safe and durable. The goal of this study was to assess the presence of S. aureus biofilms on a variety of 3D printed materials (two surgical guide resins, a photopolymer, an elastomer, and a thermoplastic elastomer filament) as compared to standard, commercially available laryngectomy tubes.C-shaped discs (15 mm in height, 20 mm in diameter, and 3 mm in thickness) were printed with five different biocompatible 3D printing materials and S. aureus growth was compared to Shiley™ laryngectomy tubes made from polyvinyl chloride. Discs of each material were inoculated with S. aureus cultures and incubated overnight. All materials were then removed from solution, washed in phosphate-buffered saline to remove planktonic bacteria, and sonicated to detach biofilms. Some solution from each disc was plated and colony-forming units were manually counted the following day. The resulting data was analyzed using a Kruskal-Wallis and Wilcoxon Rank Sum test to determine pairwise significance between the laryngectomy tube material and the 3D printed materials.The Shiley™ tube grew a median of 320 colonies (IQR 140-520), one surgical guide resin grew a median of 640 colonies (IQR 356-920), the photopolymer grew a median of 340 colonies (IQR 95.5-739), the other surgical guide resin grew a median of 431 colonies (IQR 266.5-735), the thermoplastic elastomer filament grew a median of 188 colonies (IQR 113.5-335), and the elastomer grew a median of 478 colonies (IQR 271-630). Using the Wilcoxon Rank Sum test, manual quantification showed a significant difference between biofilm formation only between the Shiley™ tube and a surgical guide resin (p = 0.018).This preliminary study demonstrates that bacterial colonization was comparable among most 3D printed materials as compared to the conventionally manufactured device. Continuation of this work with increased replicates will be necessary to determine which 3D printing materials optimally resist biofilm formation.

Biomaterials-based additive manufacturing for customized bioengineering in management of otolaryngology: a comprehensive review

Three-dimensional (3D)/four-dimensional (4D) printing, also known as additive manufacturing or fast prototyping, is a manufacturing technique that uses a digital model to generate a 3D/4D solid product. The usage of biomaterials with 3D/4D printers in the pharma and healthcare industries is gaining significant popularity. 3D printing has mostly been employed in the domain of otolaryngology to build portable anatomical models, personalized patient-centric implants, biologic tissue scaffolds, surgical planning in individuals with challenging conditions, and surgical training. Although identical to 3D printing technology in this application, 4D printing technology comprises a fourth dimension of time. With the use of 4D printing, a printed structure may alter over time under various stimuli. Smart polymeric materials are also generally denoted as bioinks are frequently employed in tissue engineering applications of 3D/4D printing. In general, 4D printing could significantly improve the safety and efficacy of otolaryngology therapies. The use of bioprinting in otolaryngology has an opportunity to transform the treatment of diseases influencing the ear, nose, and throat as well as the field of tissue regeneration. The present review briefs on polymeric material including biomaterials and cells used in the manufacturing of patient centric 3D/4D bio-printed products utilized in management of otolaryngology.

3D Printed Larynx as a Novel Simulation Tool for Window Elaboration in Medialization Laryngoplasty

OBJECTIVE

Surgical simulation training in residents has declined due to the limited exposure to cadaveric specimens. Three-dimensional (3D)-printing technology is rapidly taking an important role in different medical areas, especially in surgical specialties. It provides an alternative for resident simulation practices and for developing surgical skills before exposure to real settings. The elaboration of the thyroid window in the medialization laryngoplasty procedure requires high technical precision and experience for better outcomes.

METHODS

The computer-based 3D reconstruction model was created using computed tomograph scan images from a standard larynx. The final model was created using a deposition modeling 3D printing technique with polylactic acid filament. The model was tested for surgical simulation practice in three otolaryngology residency programs in Bogotá, Colombia.

RESULTS

The model had similar anatomic detail and it was considered very useful, safe, and relevant for surgical simulation.

CONCLUSIONS

3D printed models are a cost-effective alternative for resident training.

Application of aortic allograft in trachea transplantation

BACKGROUND

The use of tracheal implants for tracheal reconstruction remains a challenge in thoracic medicine due to the complex structure of the trachea in mammalian organisms, including smooth muscles, cartilage, mucosa, blood vessels, cilia, and other tissues, and the difficulty in achieving tracheal regeneration using implants from either allografts or synthetic biomaterials.

METHODS

This project used the Lee-Sung strain pig, a swine breed local to Taiwan, as the experimental subject. The aorta of the pig was harvested, decellularized to form the scaffold, and transplanted into the trachea of allogeneic pigs together with growth factors. Postoperative physiological function and tissue changes were observed. The postoperative physiological parameters of the LSP were monitored, and they were sacrificed after a certain period to observe the pathological changes in the tracheal epithelial cells and cartilages.

RESULTS

Overall, six LSP tracheal transplantations were performed between March 4, 2020, and March 10, 2021. These included aortic patch anastomosis for pig 1 and aortic segmental anastomosis for pigs 2-6. The shortest and longest survival periods were 1 day and 147 days, respectively. Excluding the pig that survived for only 1 day due to a ruptured graft anastomosis, all other subjects survived for over 1 month on average.

CONCLUSION

In this study, we grafted a decellularized porcine aorta into a recipient pig with a tracheal defect. We found cryopreservation of the allogeneic aorta transplantation was a feasible and safe method for the management of airway disease, and immunosuppressants were unnecessary during the treatment course.

3D Bioprinting in Otolaryngology: A Review

The evolution of tissue engineering and 3D bioprinting has allowed for increased opportunities to generate musculoskeletal tissue grafts that can enhance functional and aesthetic outcomes in otolaryngology-head and neck surgery. Despite literature reporting successes in the fabrication of cartilage and bone scaffolds for applications in the head and neck, the full potential of this technology has yet to be realized. Otolaryngology as a field has always been at the forefront of new advancements and technology and is well poised to spearhead clinical application of these engineered tissues. In this review, current 3D bioprinting methods are described and an overview of potential cell types, bioinks, and bioactive factors available for musculoskeletal engineering using this technology is presented. The otologic, nasal, tracheal, and craniofacial bone applications of 3D bioprinting with a focus on engineered graft implantation in animal models to highlight the status of functional outcomes in vivo; a necessary step to future clinical translation are reviewed. Continued multidisciplinary efforts between material chemistry, biological sciences, and otolaryngologists will play a key role in the translation of engineered, 3D bioprinted constructs for head and neck surgery.

Advantages of FDM and gamma irradiation to manufacture personalized medical devices for airway obstructions

In the early childhood population, congenital airway conditions like bronchomalacia (BM) can pose a life-threatening threat. A breakthrough technology called additive manufacturing, or 3D printing, makes it feasible to create a biomedical device that aids in the treatment of airway obstruction. This article describes how a polycaprolactone (PCL) splint for the upper airways can be created using the fusion deposition technique (FDM) and sterilized using gamma radiation. It is presented as a simple, accessible, and cost-reduced alternative that complements other techniques using more expensive and sophisticated printing methods. Thermomechanical and morphological analysis proved that FDM and sterilizing by gamma irradiation are both appropriate methods for producing splints to treat life-threatening airway blockages. Additionally, the 3D-printed splints' effectiveness in treating a young patient with BM that was life-threatening was assessed by medical professionals. In this regard, the case report of a patient with 34 months of follow-up is presented. Splints manufactured by this affordable 3D printing method successfully surpass breathing arrest in life-threatening airway obstruction in pediatric patients. The success of this procedure represents a fundamental contribution to the treatment of the population in countries where access to expensive and complex technologies is not available.

Development of tissue-engineered tracheal scaffold with refined mechanical properties and vascularisation for tracheal regeneration

Introduction: Attempted tracheal replacement efforts thus far have had very little success. Major limiting factors have been the inability to efficiently re-vascularise and mimic the mechanical properties of native tissue. The major objective of this study was to optimise a previously developed collagen-hyaluronic acid scaffold (CHyA-B), which has shown to facilitate the growth of respiratory cells in distinct regions, as a potential tracheal replacement device. Methods: A biodegradable thermoplastic polymer was 3D-printed into different designs and underwent multi-modal mechanical assessment. The 3D-printed constructs were incorporated into the CHyA-B scaffolds and subjected to in vitro and ex vivo vascularisation. Results: The polymeric backbone provided sufficient strength to the CHyA-B scaffold, with yield loads of 1.31-5.17 N/mm and flexural moduli of 0.13-0.26 MPa. Angiogenic growth factor release (VEGF and bFGF) and angiogenic gene upregulation (KDR, TEK-2 and ANG-1) was detected in composite scaffolds and remained sustainable up to 14 days. Confocal microscopy and histological sectioning confirmed the presence of infiltrating blood vessel throughout composite scaffolds both in vitro and ex vivo. Discussion: By addressing both the mechanical and physiological requirements of tracheal scaffolds, this work has begun to pave the way for a new therapeutic option for large tracheal defects.

External airway splint placement for severe pediatric tracheobronchomalacia

OBJECTIVE

To present external airway splinting with bioabsorbable airway supportive devices (ASD) for severe, life-threatening cases of pediatric tracheomalacia (TM) or tracheobronchomalacia (TBM).

METHODS

A retrospective cohort was performed for 5 pediatric patients with severe TM or TBM who underwent ASD placement. Devices were designed and 3D-printed from a bioabsorbable material, polycaprolactone (PCL). Pre-operative planning included 3-dimensional airway modeling of tracheal collapse and tracheal suture placement using nonlinear finite element (FE) methods. Pre-operative modeling revealed that triads along the ASD open edges and center were the most effective suture locations for optimizing airway patency. Pediatric cardiothoracic surgery and otolaryngology applied the ASDs by suspending the trachea to the ASD with synchronous bronchoscopy. Respiratory needs were trended for all cases. Data from pediatric patients with tracheostomy and diagnosis of TM or TBM, but without ASD, were included for discussion.

RESULTS

Five patients (2 Females, 3 Males, ages 2-9 months at time of ASD) were included. Three patients were unable to wean from respiratory support after vascular ring division; all three weaned to room air post-ASD. Two patients received tracheostomies prior to ASD placement, but continued to experience apparent life-threatening events (ALTE) and required ventilation with supraphysiologic ventilator settings. One patient weaned respiratory support successfully after ASD placement. The last patient died post-ASD due to significant respiratory co-morbidity.

CONCLUSION

ASD can significantly benefit patients with severe, unrelenting tracheomalacia or tracheobronchomalacia. Proper multidisciplinary case deliberation and selection are key to success with ASD. Pre-operative airway modeling allows proper suture placement to optimally address the underlying airway collapse.

Current Status and Future Outlook of Additive Manufacturing Technologies for the Reconstruction of the Trachea

Tracheal stenosis and defects occur congenitally and in patients who have undergone tracheal intubation and tracheostomy due to long-term intensive care. Such issues may also be observed during tracheal removal during malignant head and neck tumor resection. However, to date, no treatment method has been identified that can simultaneously restore the appearance of the tracheal skeleton while maintaining respiratory function in patients with tracheal defects. Therefore, there is an urgent need to develop a method that can maintain tracheal function while simultaneously reconstructing the skeletal structure of the trachea. Under such circumstances, the advent of additive manufacturing technology that can create customized structures using patient medical image data provides new possibilities for tracheal reconstruction surgery. In this study, the three-dimensional (3D) printing and bioprinting technologies used in tracheal reconstruction are summarized, and various research results related to the reconstruction of mucous membranes, cartilage, blood vessels, and muscle tissue, which are tissues required for tracheal reconstruction, are classified. The prospects for 3D-printed tracheas in clinical studies are also described. This review serves as a guide for the development of artificial tracheas and clinical trials using 3D printing and bioprinting.

Recent progress in the manipulation of biochemical and biophysical cues for engineering functional tissues

Tissue engineering (TE) is currently considered a cutting-edge discipline that offers the potential for developing treatments for health conditions that negatively affect the quality of life. This interdisciplinary field typically involves the combination of cells, scaffolds, and appropriate induction factors for the regeneration and repair of damaged tissue. Cell fate decisions, such as survival, proliferation, or differentiation, critically depend on various biochemical and biophysical factors provided by the extracellular environment during developmental, physiological, and pathological processes. Therefore, understanding the mechanisms of action of these factors is critical to accurately mimic the complex architecture of the extracellular environment of living tissues and improve the efficiency of TE approaches. In this review, we recapitulate the effects that biochemical and biophysical induction factors have on various aspects of cell fate. While the role of biochemical factors, such as growth factors, small molecules, extracellular matrix (ECM) components, and cytokines, has been extensively studied in the context of TE applications, it is only recently that we have begun to understand the effects of biophysical signals such as surface topography, mechanical, and electrical signals. These biophysical cues could provide a more robust set of stimuli to manipulate cell signaling pathways during the formation of the engineered tissue. Furthermore, the simultaneous application of different types of signals appears to elicit synergistic responses that are likely to improve functional outcomes, which could help translate results into successful clinical therapies in the future.

Use of 3-dimensional printing at the point-of-care to manage a complex wound in hemifacial necrotizing fasciitis: a case report

BACKGROUND

Complex facial wounds can be difficult to stabilize due to proximity of vital structures. We present a case in which a patient-specific wound splint was manufactured using computer assisted design and three-dimensional printing at the point-of-care to allow for wound stabilization in the setting of hemifacial necrotizing fasciitis. We also describe the process and implementation of the United States Food and Drug Administration Expanded Access for Medical Devices Emergency Use mechanism.

CASE PRESENTATION

A 58-year-old female presented with necrotizing fasciitis of the neck and hemiface. After multiple debridements, she remained critically ill with poor vascularity of tissue in the wound bed and no evidence of healthy granulation tissue and concern for additional breakdown towards the right orbit, mediastinum, and pretracheal soft tissues, precluding tracheostomy placement despite prolonged intubation. A negative pressure wound vacuum was considered for improved healing, but proximity to the eye raised concern for vision loss due to traction injury. As a solution, under the Food and Drug Administration's Expanded Access for Medical Devices Emergency Use mechanism, we designed a three-dimensional printed, patient-specific silicone wound splint from a CT scan, allowing the wound vacuum to be secured to the splint rather than the eyelid. After 5 days of splint-assisted vacuum therapy, the wound bed stabilized with no residual purulence and developed healthy granulation tissue, without injury to the eye or lower lid. With continued vacuum therapy, the wound contracted to allow for safe tracheostomy placement, ventilator liberation, oral intake, and hemifacial reconstruction with a myofascial pectoralis muscle flap and a paramedian forehead flap 1 month later. She was eventually decannulated and at six-month follow-up has excellent wound healing and periorbital function.

CONCLUSIONS

Patient-specific, three-dimensional printing is an innovative solution that can facilitate safe placement of negative pressure wound therapy adjacent to delicate structures. This report also demonstrates feasibility of point-of-care manufacturing of customized devices for optimizing complex wound management in the head and neck, and describes successful use of the United States Food and Drug Administration's Expanded Access for Medical Devices Emergency Use mechanism.

3D bioprinting and its innovative approach for biomedical applications

3D bioprinting or additive manufacturing is an emerging innovative technology revolutionizing the field of biomedical applications by combining engineering, manufacturing, art, education, and medicine. This process involved incorporating the cells with biocompatible materials to design the required tissue or organ model in situ for various in vivo applications. Conventional 3D printing is involved in constructing the model without incorporating any living components, thereby limiting its use in several recent biological applications. However, this uses additional biological complexities, including material choice, cell types, and their growth and differentiation factors. This state-of-the-art technology consciously summarizes different methods used in bioprinting and their importance and setbacks. It also elaborates on the concept of bioinks and their utility. Biomedical applications such as cancer therapy, tissue engineering, bone regeneration, and wound healing involving 3D printing have gained much attention in recent years. This article aims to provide a comprehensive review of all the aspects associated with 3D bioprinting, from material selection, technology, and fabrication to applications in the biomedical fields. Attempts have been made to highlight each element in detail, along with the associated available reports from recent literature. This review focuses on providing a single platform for cancer and tissue engineering applications associated with 3D bioprinting in the biomedical field.

Recent Developments in 3D Bio-Printing and Its Biomedical Applications

The fast-developing field of 3D bio-printing has been extensively used to improve the usability and performance of scaffolds filled with cells. Over the last few decades, a variety of tissues and organs including skin, blood vessels, and hearts, etc., have all been produced in large quantities via 3D bio-printing. These tissues and organs are not only able to serve as building blocks for the ultimate goal of repair and regeneration, but they can also be utilized as in vitro models for pharmacokinetics, drug screening, and other purposes. To further 3D-printing uses in tissue engineering, research on novel, suitable biomaterials with quick cross-linking capabilities is a prerequisite. A wider variety of acceptable 3D-printed materials are still needed, as well as better printing resolution (particularly at the nanoscale range), speed, and biomaterial compatibility. The aim of this study is to provide expertise in the most prevalent and new biomaterials used in 3D bio-printing as well as an introduction to the associated approaches that are frequently considered by researchers. Furthermore, an effort has been made to convey the most pertinent implementations of 3D bio-printing processes, such as tissue regeneration, etc., by providing the most significant research together with a comprehensive list of material selection guidelines, constraints, and future prospects.

Silk Fibroin Hybrids for Biological Scaffolds with Adhesive Surface and Adaptability to the Target Tissue Change

Background Regenerative Medicine (RM) is a branch of medicine that aims to regenerate tissues and organs to overcome the problems transplants entail (poor availability, risk of rejection and intense immunosuppression). To do this, RM makes use of tissue engineering (TE). This fundamental branch deals with creating biological scaffolds capable of performing the role that physiologically belongs to the extracellular matrix (ECM). In this review, we report how specific characteristics of the scaffolds (bio-compatibility, biodegradability and mechanical and conformal properties) can be obtained using 3D printing, which facilitates the emulation of physiological tissues and organs.

Purpose and scope This review reports recent advances in the fabrication method of bioactive scaffolds that can be used clinically, providing support for cell seeding and proliferation. To this end, silk fibroin, tannin and graphene were used to improve the scaffold’s electro-bio-mechanical properties. These materials in different compositions are studied to demonstrate their potential use as bio-ink in bioadhesives and cellularized and implantable 3D-printed scaffolds.

Summary of new synthesis and conclusions reached in the review Silk fibroin is a natural biopolymer; tannin, on the other hand, is a biological polyphenol, highly reactive with other molecules by nature and with promising antioxidant capabilities. Finally, graphene is nothing more than a monolayer of graphite that has been shown to implement the mechanics and electrical conductivity of the compounds in which it is inserted; it also has excellent biocompatibility and surface area, qualities that promote cell adhesion and growth.

Conclusion Polyphenols and graphene have been shown to work in synergy in improving the electro-mechanical properties of silk fibroin scaffolds. We reported optimal and potentially market-competitive bioadhesives, but above all, the proliferation of neuronal precursor cells in vitro was successfully demonstrated.

3D bioprinting of emulating homeostasis regulation for regenerative medicine applications

Homeostasis is the most fundamental mechanism of physiological processes, occurring simultaneously as the production and outcomes of pathological procedures. Accompanied by manufacture and maturation of intricate and highly hierarchical architecture obtained from 3D bioprinting (three-dimension bioprinting), homeostasis has substantially determined the quality of printed tissues and organs. Instead of only shape imitation that has been the remarkable advances, fabrication for functionality to make artificial tissues and organs that act as real ones in vivo has been accepted as the optimized strategy in 3D bioprinting for the next several years. Herein, this review aims to provide not only an overview of 3D bioprinting, but also the main strategies used for homeostasis bioprinting. This paper briefly introduces the principles of 3D bioprinting system applied in homeostasis regulations firstly, and then summarizes the specific strategies and potential trend of homeostasis regulations using multiple types of stimuli-response biomaterials to maintain auto regulation, specifically displaying a brilliant prospect in hormone regulation of homeostasis with the most recently outbreak of vasculature fabrication. Finally, we discuss challenges and future prospects of homeostasis fabrication based on 3D bioprinting in regenerative medicine, hoping to further inspire the development of functional fabrication in 3D bioprinting.

3D Printing in Otolaryngology Surgery: Descriptive Review of Literature to Define the State of the Art

BACKGROUND

Three-dimensional (3D) printing has allowed great progression in the medical field. In otolaryngology practice, 3D printing can be used for planning in case of malformation/complex surgery, for surgeon training, and for recreating missing tissues. This systematic review aimed to summarize the current benefits and the possible future application of 3D technologies in the otolaryngology field.

METHODS

A systematic review of articles that discuss the use of 3D printing in the otolaryngology field was performed. All publications without the restriction of time and that were published by December 2021 in the English language were included. Searches were performed in the PubMed, MEDLINE, Scopus, and Embase databases. Keywords used were: "3D printing", "bioprinting", "three-dimensional printing", "tissue engineering" in combination with the terms: "head and neck surgery", "head and neck reconstruction", "otology", "rhinology", "laryngology", and "otolaryngology".

RESULTS

Ninety-one articles were included in this systematic review. The articles describe the clinical application of 3D printing in different fields of otolaryngology, from otology to pediatric otolaryngology. The main uses of 3D printing technology discussed in the articles included in the review were surgical planning in temporal bone malformation, the reconstruction of missing body parts after oncologic surgery, allowing for medical training, and providing better information to patients.

CONCLUSION

The use of 3D printing in otolaryngology practice is constantly growing. However, available evidence is still limited, and further studies are needed to better evaluate the benefits of this technology.

Three-Dimensional Bioprinting with Alginate by Freeform Reversible Embedding of Suspended Hydrogels with Tunable Physical Properties and Cell Proliferation

Extrusion-based three-dimensional (3D) bioprinting is an emerging technology that allows for rapid bio-fabrication of scaffolds with live cells. Alginate is a soft biomaterial that has been studied extensively as a bio-ink to support cell growth in 3D constructs. However, native alginate is a bio-inert material that requires modifications to allow for cell adhesion and cell growth. Cells grown in modified alginates with the RGD (arginine-glycine-aspartate) motif, a naturally existing tripeptide sequence that is crucial to cell adhesion and proliferation, demonstrate enhanced cell adhesion, spreading, and differentiation. Recently, the bioprinting technique using freeform reversible embedding of suspended hydrogels (FRESH) has revolutionized 3D bioprinting, enabling the use of soft bio-inks that would otherwise collapse in air. However, the printability of RGD-modified alginates using the FRESH technique has not been evaluated. The associated physical properties and bioactivity of 3D bio-printed alginates after RGD modification remains unclear. In this study, we characterized the physical properties, printability, and cellular proliferation of native and RGD-modified alginate after extrusion-based 3D bioprinting in FRESH. We demonstrated tunable physical properties of native and RGD-modified alginates after FRESH 3D bioprinting. Sodium alginate with RGD modification, especially at a high concentration, was associated with greatly improved cell viability and integrin clustering, which further enhanced cell proliferation.

3D-Printed Pectin/Carboxymethyl Cellulose/ZnO Bio-Inks: Comparative Analysis with the Solution Casting Method

Bio-inks consisting of pectin (Pec), carboxymethyl cellulose (CMC), and ZnO nanoparticles (ZnO) were used to prepare films by solution casting and 3D-printing methods. Field emission scanning electron microscopy (FE-SEM) was conducted to observe that the surface of samples made by 3D bioprinter was denser and more compact than the solution cast samples. In addition, Pec/CMC/ZnO made by 3D-bioprinter (Pec/CMC/ZnO-3D) revealed enhanced water vapor barrier, hydrophobicity, and mechanical properties. Pec/CMC/ZnO-3D also showed strong antimicrobial activity within 12 h against S. aureus and E. coli O157: H7 bacterial strains compared to the solution cast films. Further, the nanocomposite bio-inks used for 3D printing did not show cytotoxicity towards normal human dermal fibroblast (NDFB) cells but enhanced the fibroblast proliferation with increasing exposure concentration of the sample. The study provided two important inferences. Firstly, the 3D bioprinting method can be an alternative, better, and more practical method for fabricating biopolymer film instead of solution casting, which is the main finding of this work defining its novelty. Secondly, the Pec/CMC/ZnO can potentially be used as 3D bio-inks to fabricate functional films or scaffolds and biomedical applications.

Clinical grade manufacture of 3D printed patient specific biodegradable devices for pediatric airway support

Implantable patient-specific devices are the next frontier of personalized medicine, positioned to improve the quality of care across multiple clinical disciplines. Translation of patient-specific devices requires time- and cost-effective processes to design, verify and validate in adherence to FDA guidance for medical device manufacture. In this study, we present a generalized strategy for selective laser sintering (SLS) of patient-specific medical devices following the prescribed guidance for additive manufacturing of medical devices issued by the FDA in 2018. We contextualize this process for manufacturing an Airway Support Device, a life-saving tracheal and bronchial implant restoring airway patency for pediatric patients diagnosed with tracheobronchomalacia and exhibiting partial or complete airway collapse. The process covers image-based modeling, design inputs, design verification, material inputs and verification, device verification, and device validation, including clinical results. We demonstrate how design and material assessment lead to verified Airway Support Devices that achieve desired airway patency and reduction in required Positive End-Expiratory Pressure (PEEP) after patient implantation. We propose this process as a template for general quality control of patient-specific, 3D printed implants.

The role of computer aided design/computer assisted manufacturing (CAD/CAM) and 3- dimensional printing in head and neck oncologic surgery: A review and future directions

Microvascular free flap reconstruction has remained the standard of care in reconstruction of large tissue defects following ablative head and neck oncologic surgery, especially for bony structures. Computer aided design/computer assisted manufacturing (CAD/CAM) and 3-dimensionally (3D) printed models and devices offer novel solutions for reconstruction of bony defects. Conventional free hand techniques have been enhanced using 3D printed anatomic models for reference and pre-bending of titanium reconstructive plates, which has dramatically improved intraoperative and microvascular ischemia times. Improvements led to current state of the art uses which include full virtual planning (VP), 3D printed osteotomy guides, and patient specific reconstructive plates, with advanced options incorporating dental rehabilitation and titanium bone replacements into the primary surgical plan through use of these tools. Limitations such as high costs and delays in device manufacturing may be mitigated with in house software and workflows. Future innovations still in development include printing custom prosthetics, 'bioprinting' of tissue engineered scaffolds, integration of therapeutic implants, and other possibilities as this technology continues to rapidly advance. This review summarizes the literature and serves as a summary guide to the historic, current, advanced, and future possibilities of 3D printing within head and neck oncologic surgery and bony reconstruction. This review serves as a summary guide to the historic, current, advanced, and future roles of CAD/CAM and 3D printing within the field of head and neck oncologic surgery and bony reconstruction.

Digital Light 3D Printed Bioresorbable and NIR-Responsive Devices with Photothermal and Shape-Memory Functions

Digital light processing (DLP) 3D printing is a promising technique for the rapid manufacturing of customized medical devices with high precision. To be successfully translated to a clinical setting, challenges in the development of suitable photopolymerizable materials have yet to be overcome. Besides biocompatibility, it is often desirable for the printed devices to be biodegradable, elastic, and with a therapeutic function. Here, a multifunctional DLP printed material system based on the composite of gold nanorods and polyester copolymer is reported. The material demonstrates robust near-infrared (NIR) responsiveness, allowing rapid and stable photothermal effect leading to the time-dependent cell death. NIR light-triggerable shape transformation is demonstrated, resulting in a facilitated insertion and expansion of DLP printed stent ex vivo. The proposed strategy opens a promising avenue for the design of multifunctional therapeutic devices based on nanoparticle-polymer composites.

Guide for starting or optimizing a 3D printing clinical service

Three-dimensional (3D) printing has applications in many fields and has gained substantial traction in medicine as a modality to transform two-dimensional scans into three-dimensional renderings. Patient-specific 3D printed models have direct patient care uses in surgical and procedural specialties, allowing for increased precision and accuracy in developing treatment plans and guiding surgeries. Medical applications include surgical planning, surgical guides, patient and trainee education, and implant fabrication. 3D printing workflow for a laboratory or clinical service that produces anatomic models and guides includes optimizing imaging acquisition and post-processing, segmenting the imaging, and printing the model. Quality assurance considerations include supervising medical imaging expert radiologists' guidance and self-implementing in-house quality control programs. The purpose of this review is to provide a workflow and guide for starting or optimizing laboratories and clinical services that 3D-print anatomic models or guides for clinical use.

Mathematical surface function-based design and 3D printing of airway stents

BACKGROUND

Three-dimensional (3D) printing is a method applied to build a 3D object of any shape from a digital model, and it provides crucial advantages especially for transferring patient-specific designs to clinical settings. The main purpose of this study is to introduce the newly designed complex airway stent models that are created through mathematical functions and manufactured with 3D printing for implementation in real life.

METHODS

A mathematical modeling software (MathMod) was used to design five different airway stents. The highly porous structures with designated scales were fabricated by utilizing a stereolithography-based 3D printing technology. The fine details in the microstructure of 3D printed parts were observed by a scanning electron microscope (SEM). The mechanical properties of airway stents with various designs and porosity were compared by compression test.

RESULTS

The outputs of the mathematical modeling software were successfully converted into 3D printable files and airway stents with a porosity of more than 85% were 3D printed. SEM images revealed the layered topography of high-resolution 3D printed parts. Compression tests have shown that the mathematical function-based design offers the opportunity to adjust the mechanical strength of airway stents without changing the material or manufacturing method.

CONCLUSIONS

A novel approach, which includes mathematical function-based design and 3D printing technology, is proposed in this study for the fabrication of airway stents as a promising tool for future treatments of central airway pathologies.

Advances in 3D bioprinting of tissues/organs for regenerative medicine and in-vitro models

Tissue/organ shortage is a major medical challenge due to donor scarcity and patient immune rejections. Furthermore, it is difficult to predict or mimic the human disease condition in animal models during preclinical studies because disease phenotype differs between humans and animals. Three-dimensional bioprinting (3DBP) is evolving into an unparalleled multidisciplinary technology for engineering three-dimensional (3D) biological tissue with complex architecture and composition. The technology has emerged as a key driver by precise deposition and assembly of biomaterials with patient's/donor cells. This advancement has aided in the successful fabrication of in vitro models, preclinical implants, and tissue/organs-like structures. Here, we critically reviewed the current state of 3D-bioprinting strategies for regenerative therapy in eight organ systems, including nervous, cardiovascular, skeletal, integumentary, endocrine and exocrine, gastrointestinal, respiratory, and urinary systems. We also focus on the application of 3D bioprinting to fabricated in vitro models to study cancer, infection, drug testing, and safety assessment. The concept of in situ 3D bioprinting is discussed, which is the direct printing of tissues at the injury or defect site for reparative and regenerative therapy. Finally, issues such as scalability, immune response, and regulatory approval are discussed, as well as recently developed tools and technologies such as four-dimensional and convergence bioprinting. In addition, information about clinical trials using 3D printing has been included.

Tracheobronchomalacia and Excessive Dynamic Airway Collapse: Current Concepts and Future Directions

Tracheobronchomalacia (TBM) and excessive dynamic airway collapse (EDAC) are airway abnormalities that share a common feature of expiratory narrowing but are distinct pathophysiologic entities. Both entities are collectively referred to as expiratory central airway collapse (ECAC). The malacia or weakness of cartilage that supports the tracheobronchial tree may occur only in the trachea (ie, tracheomalacia), in both the trachea and bronchi (TBM), or only in the bronchi (bronchomalacia). On the other hand, EDAC refers to excessive anterior bowing of the posterior membrane into the airway lumen with intact cartilage. Clinical diagnosis is often confounded by comorbidities including asthma, chronic obstructive pulmonary disease, obesity, hypoventilation syndrome, and gastroesophageal reflux disease. Additional challenges include the underrecognition of ECAC at imaging; the interchangeable use of the terms TBM and EDAC in the literature, which leads to confusion; and the lack of clear guidelines for diagnosis and treatment. The use of CT is growing for evaluation of the morphology of the airway, tracheobronchial collapsibility, and extrinsic disease processes that can narrow the trachea. MRI is an alternative tool, although it is not as widely available and is not used as frequently for this indication as is CT. Together, these tools not only enable diagnosis, but also provide a road map to clinicians and surgeons for planning treatment. In addition, CT datasets can be used for 3D printing of personalized medical devices such as stents and splints. An invited commentary by Brixey is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

Tissue-engineered composite tracheal grafts create mechanically stable and biocompatible airway replacements

We tested composite tracheal grafts (CTG) composed of a partially decellularized tracheal graft (PDTG) combined with a 3-dimensional (3D)-printed airway splint for use in long-segment airway reconstruction. CTG is designed to recapitulate the 3D extracellular matrix of the trachea with stable mechanical properties imparted from the extraluminal airway splint. We performed segmental orthotopic tracheal replacement in a mouse microsurgical model. MicroCT was used to measure graft patency. Tracheal neotissue formation was quantified histologically. Airflow dynamic properties were analyzed using computational fluid dynamics. We found that CTG are easily implanted and did not result in vascular erosion, tracheal injury, or inflammation. Graft epithelialization and endothelialization were comparable with CTG to control. Tracheal collapse was absent with CTG. Composite tracheal scaffolds combine biocompatible synthetic support with PDTG, supporting the regeneration of host epithelium while maintaining graft structure.

Development of a High-Fidelity, 3D Printed Otoplasty Surgical Simulator

IMPORTANCE

Prominotia has functional and esthetic impact for the child and family and proficiency in otoplasty requires experiential rehearsal.

OBJECTIVES

To design and validate an anatomically accurate, 3D printed prominotia simulator for rehearsal of otoplasties.

METHODS

A 3D prominotia model was designed from a computed tomographic (CT) scan and edited in 3-matic software. Negative molds were 3D printed and filled with silicone. Expert surgeons performed an otoplasty procedure on these simulators and provided Likert-based feedback.

RESULTS

Six expert surgeons with a mean of 14.3 years of practice evaluated physical qualities, realism, performance, and value of the simulator. The simulator was rated on a scale of 1 (no value) to 5 (great value) and scored 3.83 as a training tool, 3.83 as a competency evaluation tool, and 4 as a rehearsal tool.

CONCLUSIONS

Expert validation rated the otoplasty simulator highly in physical qualities, realism, performance, and value. With minor modifications, this model demonstrates valuable educational potential.

Biofabrication approaches and regulatory framework of metastatic tumor-on-a-chip models for precision oncology

The complexity of the tumor microenvironment (TME) together with the development of the metastatic process are the main reasons for the failure of conventional anticancer treatment. In recent years, there is an increasing need to advance toward advanced in vitro models of cancer mimicking TME and simulating metastasis to understand the associated mechanisms that are still unknown, and to be able to develop personalized therapy. In this review, the commonly used alternatives and latest advances in biofabrication of tumor‐on‐chips, which allow the generation of the most sophisticated and optimized models for recapitulating the tumor process, are presented. In addition, the advances that have allowed these new models in the area of metastasis, cancer stem cells, and angiogenesis are summarized, as well as the recent integration of multiorgan‐on‐a‐chip systems to recapitulate natural metastasis and pharmacological screening against it. We also analyze, for the first time in the literature, the normative and regulatory framework in which these models could potentially be found, as well as the requirements and processes that must be fulfilled to be commercially implemented as in vitro study model. Moreover, we are focused on the possible regulatory pathways for their clinical application in precision medicine and decision making through the generation of personalized models with patient samples. In conclusion, this review highlights the synergistic combination of three‐dimensional bioprinting systems with the novel tumor/metastasis/multiorgan‐on‐a‐chip systems to generate models for both basic research and clinical applications to have devices useful for personalized oncology.

Personalized 3D-Printed Bioresorbable Airway External Splint for Tracheomalacia Combined With Congenital Heart Disease

Severe tracheomalacia (TM) patients with respiratory symptoms need surgical intervention, including aortopexy, internal stents or external splint. While some patients continue to have respiratory symptoms after tracheal relief, and there is no evidence to support any one surgery therapy over another. Here we introduce a clinical safety and efficacy of the three-dimensional (3D)-printed bioresorbable airway external splints in treating congenital heart disease (CHD) patients with severe TM. From May 2019 to September 2020, nine patients with severe TM were enrolled. The median age was 5 months (range, 3–25 months), and the median weight was 7.5 kg (range, 3–15 kg). All patients had wheezing, and two patients were assisted by machine ventilation (MV) preoperatively. The median length of TM was 1.5 cm (range, 1.0–3.0 cm). All patients underwent suspension of a “C”-shaped lumen airway external splint, which were designed in SOLIDWORKS and made of polycaprolactone (PCL). The airway external splint could provided effective support for at least 6 months and was completely degraded into carbon dioxide and water within 2–3 years. The median time of postoperative machine assisted ventilation was 23.7 h (range, 3.3–223.4 h), and the median time of ICU stay was 9 days (range, 4–25 days). The median follow-up time was 18 months (range, 12–24 months). Respiratory symptoms were all relieved, and no external splint-associated complications occurred. The 3D computed tomography reconstruction showed no airway stenosis. Personalized 3D-printed bioresorbable airway external splint can not only limit external compression and prevent airway collapse but also ensure the growth potential of the airway, which is a safe, reliable and effective treatment for CHD with TM.

Novel vision restoration techniques: 3D bioprinting, gene and stem cell therapy, optogenetics, and the bionic eye

BACKGROUND

Vision restoration has been one of the most sought-after goals of ophthalmology because of its inception. Despite these problems being tackled from numerous different perspectives, a concrete solution has not yet been achieved. An optimal solution will have significant implications on the patient's quality of life, socioeconomic status, and mental health.

METHODS

This article will explore new and innovative approaches with one common aim-to restore functional vision for the visually impaired. These novel techniques include 3D bioprinting, stem cell therapy, gene therapy, implantable devices, and optogenetics.

RESULTS

While the techniques mentioned above show significant promise, they are currently in various stages of development ranging from clinical trials to commercial availability. Restoration of minimal vision in specific cases has already been achieved by the different methods but optimization of different parameters like biocompatibility, spatiotemporal resolution, and minimizing the costs are essential for widespread use.

CONCLUSION

The developments over the past decade have resulted in multiple milestones in each of the techniques with many solutions getting approved by the FDA. This article will compare these novel techniques and highlight the major advantages and drawbacks of each of them.

Starting a medical 3D printing lab for otolaryngology-head and neck surgery collaboration

OBJECTIVE

To evaluate the different strategies for developing and maintaining a 3-dimensional (3D) printing lab.

METHODS

We evaluated two printing labs and compared their structure, integration, and production.

RESULTS

While one lab was initiated by a clinician and the other by a technical expert, both labs followed a similar series of steps to develop their lab. Each identified a key clinical need, developed a collaborative team, found financial support, and discovered options for sustainability.

CONCLUSIONS

While there is no correct path for developing a 3D printing lab, depending on the existing infrastructure and the clinical need, one may choose a certain initial structure for a lab while following a list of common necessary steps.

Biomechanical properties of the ex vivo porcine trachea: A benchmark for three-dimensional bioprinted airway replacements

PURPOSE

Combining tissue engineering and three-dimensional (3D) printing may allow for the introduction of a living functional tracheal replacement graft. However, defining the biomechanical properties of the native trachea is a key prerequisite to clinical translation. To achieve this, we set out to define the rotation, axial stretch capacity, and positive intraluminal pressure capabilities for ex vivo porcine tracheas.

STUDY DESIGN

Animal study.

MATERIALS AND METHODS

Six full-length ex vivo porcine tracheas were bisected into 5.5 cm segments. Maximal positive intraluminal pressure was measured by sealing segment ends with custom designed 3D printed caps through which a pressure transducer was introduced. Axial stretch capacity and rotation were evaluated by stretching and rotating the segments along their axis between two clamps, respectively.

RESULTS

Six segments were tested for axial lengthening and the average post-stretch length percentage was 148.92% (range 136.81-163.48%, 95% CI 153-143%). The mean amount of length gain achieved per cartilaginous ring was 7.82% (range 4.71-10.95%, 95% CI 6.3-9.35%). Four tracheal segments were tested for maximal positive intraluminal pressure, which was over 400 mmHg. Degree of rotation testing found that the tracheal segments easily transformed 180° in anterior-posterior bending, lateral bending, and axial rotational twisting.

CONCLUSIONS

We define several biomechanical properties of the ex vivo porcine trachea by reporting the rotation, axial stretch capacity, and positive intraluminal pressure capabilities. We hope that this will aid future work in the clinical translation of 3D bioprinted airway replacement grafts and ensure their compatibility with native tracheal properties.