Evolution and Variations of the Ovine Model of Spina Bifida.

Spina bifida is the most common congenital anomaly of the central nervous system and the first non-fatal fetal lesions to be addressed by fetal intervention. While research in spina bifida has been performed in rodent, nonhuman primate, and canine models, sheep have been a model organism for the disease. This review summarizes the history of development of the ovine model of spina bifida, previous applications, and translation into clinical studies. Initially used by Meuli et al. [Nat Med. 1995;1(4):342-7], fetal myelomeningocele defect creation and in utero repair demonstrated motor function preservation. The addition of myelotomy in this model can reproduce hindbrain herniation malformations, which is the leading cause of mortality and morbidity in humans. Since inception, the ovine models have been validated numerous times as the ideal large animal model for fetal repair, with both locomotive scoring and spina bifida defect scoring adding to the rigor of this model. The ovine model has been used to study different methods of myelomeningocele defect repair, the application of various tissue engineering techniques for neuroprotection and bowel and bladder function. The results of these large animal studies have been translated into human clinical trials including Management of Meningocele Study (MOMS) trial that established current standard of care for prenatal repair of spina bifida defects, and the ongoing trials including the Cellular Therapy for In Utero Repair of Myelomeningocele (CuRe) trial using a stem cell patch for repair. The advancement of these life savings and life-altering therapies began in sheep models, and this notable model continues to be used to further the field including current work with stem cell therapy.

Percutaneous pelvic fixation model: an affordable and realistic simulator for pelvic trauma training.

PURPOSE: To describe the construction and use of a percutaneous pelvic fixation model, evaluate its translational validity among fellowship-trained orthopedic trauma surgeons, and investigate the importance of specific criteria for effective competency-based assessment of pelvic fixation techniques. METHODS: Five orthopedic trauma surgeons were asked to place percutaneous wires on a pelvic fixation model, including anterior column (antegrade/retrograde), posterior column (antegrade/retrograde), supra-acetabular, transsacral, and iliosacral. Evaluation criteria included successful wire placement, redirections, cortical breaches, procedure duration, radiation exposure, and quality of fluoroscopic views. Following completion, participants were provided a survey to rate the model. RESULTS: There were no differences between approaches on successful screw placement, wire redirections, or fluoroscopic quality. Antegrade approaches to the anterior and posterior columns took longer (p = 0.008) and used more radiation (p = 0.02). There was also a trend toward more cortical breaches with the antegrade anterior column approach (p = 0.07). Median ratings among surgeons were 4 out of 5 for their overall impression and its accuracy in tactile response, positioning constraints, and fluoroscopic projections. Learning parameters considered most important to the progression of trainees (most to least important) were successful screw placement, corridor breaches, wire redirections, quality of fluoroscopic views, radiation exposure, and procedure duration. CONCLUSION: In being affordable, accessible, and realistic, this percutaneous pelvic fixation model represents an opportunity to advance orthopedic surgery education globally. Future research is needed to validate the findings of this pilot study and to expand upon how trainees should be evaluated within simulations and the operating room to optimize skill progression.

Apple polyphenols exhibits chondroprotective changes of synovium and prevents knee osteoarthritis.

Apple polyphenols (AP) have strong antioxidant and anti-inflammatory properties. We examined the effects of AP on the progression of osteoarthritis (OA) AP was administered to surgically-induced OA model rats for 4 or 8 weeks. This treatment suppressed inflammation and oxidative stress in the synovium, resulting in a decrease in the OA severity score, and the expression of tumor necrosis factor (TNF)-α and matrix metalloproteinase (MMP)-13 in the synovium. It was suggested that long-term administration of AP may be effective for the treatment of OA. In addition, superoxide dismutase (SOD) activity was enhanced in serum samples by AP. AP or its constituent procyanidin B2 (PC) were added to HIG-82 synoviocytes. The results showed that AP enhanced cell proliferation and hyaluronan production. This indicates that AP may improve synovial conditions in OA and suppress OA progression. These effects may be attributed to the antioxidant and anti-inflammatory properties of AP.

A novel surgical model for the preclinical assessment of the osseointegration of dental implants: a surgical protocol and pilot study results.

BACKGROUND: Dental implants are considered the gold standard replacement for missing natural teeth. The successful clinical performance of dental implants is due to their ability to osseointegrate with the surrounding bone. Most dental implants are manufactured from Titanium and it alloys. Titanium does however have some shortcomings so alternative materials are frequently being investigated. Effective preclinical studies are essential to transfer the innovations from the benchtop to the patients. Many preclinical studies are carried out in the extra-oral bones of small animal models to assess the osseointegration of the newly developed materials. This does not simulate the oral environment where the dental implants are subjected to several factors that influence osseointegration; therefore, they can have limited clinical value. AIM: This study aimed to develop an appropriate in-vivo model for dental implant research that mimic the clinical setting. The study evaluated the applicability of the new model and investigated the impact of the surgical procedure on animal welfare. MATERIALS AND METHODS: The model was developed in male New Zealand white rabbits. The implants were inserted in the extraction sockets of the secondary incisors in the maxilla. The model allows a split-mouth comparative analysis. The implants' osseointegration was assessed clinically, radiographically using micro-computed tomography (µ-CT), and histologically. A randomised, controlled split-mouth design was conducted in 6 rabbits. A total of twelve implants were inserted. In each rabbit, two implants; one experimental implant on one side, and one control implant on the other side were applied. Screw-shaped implants were used with a length of 8 mm and a diameter of 2 mm. RESULTS: All the rabbits tolerated the surgical procedure well. The osseointegration was confirmed clinically, histologically and radiographically. Quantitative assessment of bone volume and mineral density was measured in the peri-implant bone tissues. The findings suggest that the new preclinical model is excellent, facilitating a comprehensive evaluation of osseointegration of dental implants in translational research pertaining to the human application. CONCLUSION: The presented model proved to be safe, reproducible and required basic surgical skills to perform.

Distal Pancreatic Resection with Splenectomy in the Rat: A Pancreatic Fistula Model to Investigate Postsurgical Damage?

BACKGROUND: Postoperative pancreatic fistula (POPF) is a major complication in pancreatic surgery and can cause considerable postoperative morbidity. Advanced surgical-technical approaches to prevent POPF did not yield a substantial improvement. To investigate innovative treatments, experimental animal models of distal pancreatic resection and pancreaticoduodenectomy are of fundamental importance. After a failed attempt to replicate a previously described rat model for pancreatic fistula induction, we proceeded to distal pancreatic resection with splenectomy to provoke pancreatic leakage and generate a suitable animal model. METHODS: Distal pancreatic resection with splenectomy was performed in 40 rats. The rats were sacrificed on postoperative day (POD) 1, 2, 4, 6, 8, or 10, and the abdominal cavity was explored. Ascites probes were collected pre- and postoperatively for the detection of pancreas amylase and lipase. Tissue samples from the naïve pancreas (POD 0) and the postoperatively harvested remnant were evaluated histologically. The extent of necrosis was determined, and samples were examined for neutrophil infiltration. TUNEL staining served for the verification of necrosis in distinct cases. Immunohistochemistry of Ki67, von Willebrand factor, and CD68 was performed to evaluate proliferation, blood-vessel sprouting, and macrophage invasion. RESULTS: The rats showed no clinical symptoms or severe complications in the postoperative course up to 10 days. Abdominal exploration revealed adhesions in the upper abdomen, but no intra-abdominal fluid accumulations were found. Signs of inflammation and tissue damage were evident at the pancreatic resection margin on histological examination whereas the naïve pancreatic tissue was widely unaffected. Statistically significant differences were seen between the preoperative and postoperative extent of necrosis, the presence of neutrophil infiltrate, and levels of ascitic amylase and lipase. Immunohistochemical staining on Ki67, von Willebrand factor, and CD68 did not reveal any workable results on nonstatistical examination, and it was therefore not considered for further analyses. CONCLUSION: Creating a functional animal model of pancreatic fistula that reflects the clinical and pathophysiological impact of pancreatic leakage in humans has not been achieved. Our approach of left pancreatic resection recapitulated inflammation and tissue damage, early events in the development of fistulas, and it could be suitable for the experimental testing of novel targeting methods.

Effect of Oral Branched-Chain Amino Acids and Glutamine Supplementation on Skeletal Muscle Atrophy After Total Gastrectomy in Rat Model.

BACKGROUND: Sarcopenia is closely related to short-term outcomes of surgery and long-term prognosis. After gastrectomy, a decrease in muscle strength occurs because of insufficient nutrient intake and disturbed digestive function. Branched-chain amino acids (BCAAs) and glutamine (Gln) play vital roles in the signaling pathways regulating protein synthesis and protein degradation. In this study, we investigated the effects of BCAA and Gln supplementation alone or in combination on skeletal muscle atrophy after total gastrectomy in a rat model. METHODS: Male Wistar rats were divided into five groups: (1) sham operation (n = 8); (2) total gastrectomized rats (TG [control group], n = 16); (3) TG with BCAA (TG-B, n = 16); (4) TG with Gln (TG-G, n = 16); and (5) TG with BCAA and Gln (TG-BG, n = 16). In all groups, body weight, muscle weight, and marker for muscle metabolism were examined. RESULTS: Weight gain was significantly greater in the TG-BG group (130.5%) than in the TG group (108.1%) at 15 wk (P < 0.05). The gastrocnemius muscle weight was significantly higher for TG-BG (2.84 g) than for TG (2.44 g) at 15 wk (P < 0.05). Western blotting indicated that atrogin-1 and MuRF1 levels were lower in the TG-BG group than in the TG group but were not suppressed in the TG-B or TG-G group. CONCLUSIONS: In a rodent sarcopenia model induced by TG, the administration of BCAA in combination with Gln more effectively inhibited muscle atrophy than the administration of BCAA or Gln alone.

"Barbed snore surgery" simulator: a low-cost surgical model.

BACKGROUND: "Barbed snore surgery" (BSS) represents one of the last innovation for obstructive sleep apnea syndrome (OSAS) surgical management. Although this technique represents an effective and minimally invasive surgery, it is not still widespread in many ENT centers. The aim of our study was to develop an inexpensive surgical simulator useful to expedite the surgical learning curve for BSS in untrained ENT surgeons. MODEL ASSEMBLY: The simulator is a simple model composed of a manually shaped silicone palate (3 × 4 × 1 cm) fixed on a resin skeleton (21 × 16 × 12 cm) using a transparent silicon rubber. The mandible is fixed bilaterally with the aid of two screws allowing for modular inter-incisive distance. SIMULATION: Barbed anterior pharyngoplasty (BAPh) was readily performed on the simulator to show the feasibility of this BSS model. All surgical steps were carried out determining a lift and a shortening of the palate as in real surgery. CONCLUSIONS: This is the first surgical model that provides a realistic, easily repeatable training in the performance of BSS. Our BSS surgical model is very inexpensive with a cost of approximately 19.25$ dollars and it is manufactured to facilitate a worldwide diffusion of this promising palatal surgery for OSAS.

Ex-vivo surgical model for "Barbed Snore Surgery": a feasibility study.

INTRODUCTION: The "Barbed Snore Surgery" is one of the last technical innovations in palatal surgery for Obstructive Sleep Apnea. The availability of a low-cost surgical model able to replicate tissue consistency and main anatomical structures could be fundamental for the spreading of this surgery. The aim of this study was to assess the feasibility of an ex-vivo ovine model in the surgical training of BSS. METHODS: After adequate preparation of adult lamb heads, a post-graduate student with no surgical expertise was guided by a skilled surgeon in the execution of two BSS procedures: "Barbed Roman Blinds Technique" and "Barbed Anterior Pharyngoplasty". Anatomical limitations and similarity with the human tissue were assessed and recorded during the simulation. RESULTS: All the procedures were successfully completed. Despite proportional differences, the palatal tissue was assessed as similar in consistency and thickness to the human tissue. The simulation was considered satisfactory and suitable for surgical training. CONCLUSION: This ex-vivo ovine surgical model could represent the right tool for BSS training thanks to readily available and inexpensive specimens. Moreover, it appears to present the realistic anatomy and tissue consistence essential for an adequate surgical simulation.

Evaluation of the effects of gastrectomy on the development of metabolic bone disease.

BACKGROUND: Metabolic bone disease after gastrectomy is one of the complications leading to deterioration in quality of life. The exact mechanism of the metabolic bone disease remains unclear. To clarify the cause of metabolic bone disease after gastrectomy, we evaluated the associations between the method of gastrectomy and the development of metabolic bone disease in a rat model. METHODS: Rats were assigned to four groups as follows: (1) sham operation (control group); (2) resection of the glandular stomach with Billroth I reconstruction (RGBI group); (3) Roux-en-Y anastomosis preserving the secretory function of the whole stomach (PSRY group); and (4) total gastrectomy with Roux-en-Y reconstruction (TGRY group). In all groups, body weight, serum biochemistry (total protein, albumin, calcium, phosphorus, tartrate-resistant acid phosphatase, and bone alkaline phosphatase), bone density, and bone breaking strength were measured. RESULTS: Body weights and serum calcium levels were significantly lower in the three operation groups compared with the control group. Bone density was significantly lower in the PSRY and TGRY groups compared with the control group. Bone breaking strength was significantly lower in the three operation groups compared with the control group. CONCLUSIONS: Surgical methods led to metabolic bone disease. However, exclusion of the duodenum from food passage had major influence to reduction in bone density and breaking strength. A stomach-preserving procedure and physiological reconstruction which enable food passage through duodenum and proximal jejunum contribute to mitigation of metabolic bone disease.

Transforming Growth Factor-ß3 Therapy Delays Postoperative Reossification and Improves Craniofacial Growth in Craniosynostotic Rabbits.

Postoperative reossification is a common clinical correlate following surgery. It has been suggested that an underexpression of transforming growth factor-ß3 (TGF-ß3) may be related to craniosynostosis and postoperative reossification. Adding TGF-ß3 may delay reossification and improve postoperative growth. The present study was designed to test this hypothesis. Thirty 10-day-old New Zealand white rabbits with hereditary coronal suture synostosis were divided into three groups: (1) suturectomy controls (n = 14), (2) suturectomy treated with bovine serum albumin (n = 8), and (3) suturectomy treated with TGF-ß3 protein (n = 8). At 10 days of age, a 3-mm × 15-mm coronal suturectomy was performed, and serial three-dimensional (3D) computed tomography (CT) scans and cephalographs were taken at 10, 25, 42, and 84 days of age. Calvaria were harvested at 84 days of age for histomorphometric analysis. Mean differences were analyzed using a group by age analysis of variance. Analysis of the 3D CT scan data revealed that sites treated with TGF-ß3 had significantly (P < .05) greater defect areas and significantly (P < .05) greater intracranial volumes through 84 days of age compared with controls. Histomorphometry showed that sites treated with TGF-ß3 had patent suturectomy sites and significantly (P < .001) less new bone in the suturectomy site compared with controls. Serial radiograph data revealed significant (P < .05) differences in craniofacial growth from 25 to 84 days in TGF-ß3-treated rabbits compared with controls. Data show that TGF-ß3 administration delayed reossification and improved craniofacial growth in this rabbit model. These findings also suggest that this molecular-based therapy may have potential clinical use.

Training Veterinary Students to Perform Ovariectomy Using theMOOSE Spay Model with Traditional Method versus the Dowling Spay Retractor.

Educators understand the importance of developing safe and effective methods to teach veterinary students basic surgical skills. Ovariectomy (OVE) is a procedure that employs many of the skills agreed to be vital for a newly graduated veterinarian. This study endeavored to compare two methods of teaching OVE on a model based on assessment of procedure time and skill performance scores. Students' opinions regarding their experience are also reported. Students performed the Dowling Spay Retractor (DSR) method more quickly (p<.001) but with performance scores similar to the traditional (T) method depicted in textbooks. Students responded positively when surveyed regarding their experience with the training and the DSR method.

The Effect of Preoperative Three Dimensional Modeling and Simulation on Outcome of Intracranial Aneursym Surgery.

OBJECTIVE: Three-dimensional (3D) printing in vascular surgery is trending and is useful for the visualisation of intracranial aneurysms for both surgeons and trainees. The 3D models give the surgeon time to practice before hand and plan the surgery accordingly. The aim of this study was to examine the effect of preoperative planning with 3D printing models of aneurysms in terms of surgical time and patient outcomes. METHODS: Forty patients were prospectively enrolled in this study and divided into two groups : groups I and II. In group I, only the angiograms were studied before surgery. Solid 3D modelling was performed only for group II before the operation and was studied accordingly. All surgeries were performed by the same senior vascular neurosurgeon. Demographic data, surgical data, both preoperative and postoperative modified Rankin scale (mRS) scores, and Glasgow outcome scores (GOS) were evaluated. RESULTS: The average time of surgery was shorter in group II, and the difference was statistically significant between the two groups (p<0.001). However, no major differences were found for the GOS, hospitalisation time, or mRS. CONCLUSION: This study is the first prospective study of the utility of 3D aneurysm models. We show that 3D models are useful in surgery preparation. In the near future, these models will be used widely to educate trainees and pre-plan surgical options for senior surgeons.

Cleft lip and palate surgery simulator: Open source simulation model.

Objective: Cleft lip and palate is the most common craniofacial birth anomaly and requires surgery in the first year of life. However, craniofacial surgery training opportunities are limited. The aim of this study was to present and evaluate an open-source cleft lip and palate hybrid (casting and three-dimensional (3D) printing) simulation model which can be replicated at low cost to facilitate the teaching and training of cleft surgery anatomy and techniques. Design: The soft tissue component of the cleft surgery training model was casted using a 3D printed 5-component mold and silicone. The bony structure was designed to simulate the facial anatomy and to hold the silicone soft tissue. Setting: Two groups, one group of trainees and one group of expert surgeons, at University Hospital Basel in Switzerland and Pontifical Catholic University of Chile in Santiago, Chile, tested the cleft lip and palate simulation model. Participants completed a Likert-based face and content validity questionnaire to assess the realism of the model and its usefulness in surgical training. Results: More than 70 % of the participants agreed that the model accurately simulated human tissues found in patients with unilateral cleft lip and palate. Over 60 % of the participants also agreed that the model realistically replicated surgical procedures. In addition, 80-90 % of the participants found the model to be a useful and appropriate tool for teaching the anatomy and surgical techniques involved in performing unilateral cleft lip and palate repair. Conclusion: This open-source protocol provides a cost-effective solution for surgeons to introduce the cleft morphology and surgical techniques to trainees on a regular basis. It addresses the current financial barrier that limits access to commercially available models during the early stages of surgeon training prior to specialization in the field.

Descemet membrane endothelial keratoplasty (DMEK) aquarium: Diving in to learn DMEK surgical concepts.

A novel simulation model (without using human corneas) has been described for understanding the surgical concepts and developing tactile reflexes of Descemet membrane (DM) endothelium scroll manipulation and orientation in the anterior chamber, which are necessary for performing Descemet membrane endothelial keratoplasty (DMEK). Termed the "DMEK aquarium," this model helps facilitate the understanding of different maneuvers of the DM graft needed inside the fluid-filled anterior chamber, like unrolling or unfolding, flipping or inversion, and checking orientation and centration in the host cornea. A stepwise plan for surgeons starting to learn DMEK utilizing various available resources is also suggested.

The histopathological features of the surgical endometriosis model using systemic autoimmune disease-prone mice.

Endometriosis is a common gynecological disease that affects women of reproductive age in which the uterine endometrium grows outside the uterus. Origin of the ectopic endometrium is thought to be the retrograde endometrium through the oviducts. However, factors that determine the adherence and proliferation of the ectopic endometrium have not been revealed. Importantly, systemic autoimmune diseases are considered a key factor in the endometriosis onset. Herein, we established a surgical endometriosis rodent model using autoimmune disease-prone MRL/MpJ-Faslpr/lpr (MRL/lpr) and MRL/+ mice to provide basic evidence of the relationship between autoimmune disease and endometriosis. Endometriosis lesions were successfully induced in two regions after transplanting uterine tissues from donor mice into the peritoneal cavity of recipient mice: the peritoneum or adipose tissue around the transplantation point (proximal lesions) and the gastrosplenic ligament or intestinal mesentery far from the transplantation site (distal lesions). Distal lesions were observed only in MRL/lpr mice, whereas endometriosis lesions showed no genotype- or region-related differences in the histology and distribution of sex hormone receptors and T cells. In contrast, transplanted uterine tissues in donor MRL/lpr mice exhibited a large infiltration of T cells in the lamina propria. Splenomegaly was more common in recipient than that in donor MRL/lpr mice. These results suggest that the infiltration of endogenous T cells in the endometrium alters the growth features of ectopic endometrium, possibly affecting the severity of endometriosis in patients with systemic autoimmune diseases.

Endovascular treatment simulations using a novel in vitro brain arteriovenous malformation model based on three-dimensional printing millifluidic technology.

BACKGROUND: Brain arteriovenous malformations (bAVM) are complex vascular diseases. Several models have been used to simulate endovascular treatments; thus in vitro models have not been widely employed because it has been difficult to recreate realistic phantoms of this disease. OBJECTIVE: To describe the development and evaluate the preliminary experience of a novel bAVM in vitro model for endovascular embolization using millifluidic three-dimensional (3D) printing technology. METHODS: We designed a bAVM phantom starting from simple to more complex designs, composed of a nidus, feeding arteries and draining vein. We recreate the design by using millifluidic technology with stereolithography 3D printing. Structural and functional tests were performed using angiographic images and computer flow dynamics. Treatment simulations with ethylene vinyl alcohol were tested using two different microcatheter position techniques. A Likert-scale questionnaire was applied to perform a qualitative evaluation of the model. RESULTS: We developed a realistic model of a bAVM with hollow channels. The structural evaluation showed a high precision of the 3D printing process. Embolization tests with the liquid agent gave similar sensations and material behaviour as in vivo cases. There were no significant differences between microcatheter position techniques, thus we observed a trend for better nidus filling with a deeper in-nidus position technique. CONCLUSIONS: We were able to create and test a novel bAVM in vitro model with stereolithography 3D printing in resin. It showed a high capacity for simulating endovascular embolization characteristics, with an excellent user experience. It could be potentially used for training and testing of bAVM embolizations.

Reporting ChAracteristics of cadaver training and sUrgical studies: The CACTUS guidelines.

INTRODUCTION: Recent systematic reviews highlighted increasing use of cadaveric models in the surgical training, but reports on the characteristics of the models and their impact on training are lacking, as well as standardized recommendations on how to ensure the quality of surgical studies. The aim of our survey was to provide an easy guideline that would improve the quality of the studies involving cadavers for surgical training and research. METHODS: After accurate literature review regarding surgical training on cadaveric models, a draft of the CACTUS guidelines involving 10 different items was drawn. Afterwards, the items were improved by questionnaire uploaded and spread to the experts in the field via Google form. The guideline was then reviewed following participants feedback, ergo, items that scored between 7 and 9 on nine-score Likert scale by 70% of respondents, and between 1 and 3 by fewer than 15% of respondents, were included in the proposed guideline, while items that scored between 1 and 3 by 70% of respondents, and between 7 and 9 by 15% or more of respondents were not. The process proceeded with Delphi rounds until the agreement for all items was unanimous. RESULTS: In total, 42 participants agreed to participate and 30 (71.4%) of them completed the Delphi survey. Unanimous agreement was almost always immediate concerning approval and ethical use of cadaver and providing brief outcome statement in terms of satisfaction in the use of the cadaver model through a short questionnaire. Other items were subjected to the minor adjustments. CONCLUSION: 'CACTUS' is a consensus-based guideline in the area of surgical training, simulation and anatomical studies and we believe that it will provide a useful guide to those writing manuscripts involving human cadavers.

Right Ventricular Outflow Tract Surgical Resection in Young, Large Animal Model for the Study of Alternative Cardiovascular Patches.

Tetralogy of Fallot (ToF) is a severe congenital heart defect (CHD) that requires surgical reconstruction soon after birth. Reconstructive surgery involves the implantation of synthetic cardiovascular patches to widen the right ventricular outflow tract (RVOT) and repair defects in the septal wall. However, synthetic patches can cause complications for these patients later in life as they do not integrate or adapt in the tissue of a growing patient; a limitation that could be solved with the development of a patch fabricated from a degradable biomaterial. Unfortunately, the lack of appropriate pre-clinical models has hindered the development of novel patch materials. Currently, most studies use rodent models to study the efficacy of new patch materials; however, large animal models are necessary to develop realistically sized patches in a clinically relevant growing heart where gradients in diffusion and length scales for cell migration are more similar to the human. Here, we describe a novel method by which a Satinsky vascular clamp is used to isolate RVOT muscle for resection followed by implantation of a cardiovascular patch in an appropriately young, rapidly growing porcine model.

Tissue engineered endothelial keratoplasty in rabbit: tips and tricks.

PURPOSE: To report a detailed surgical procedure of tissue engineered endothelial keratoplasty (TEEK) in a rabbit model and its postoperative evaluation. METHODS: TEEKs were prepared 7 days before transplantation by seeding human or rabbit corneal endothelial cells on either femtosecond laser-cut ultrathin human stromal lamellae (fs-UTSL) or femtosecond laser-cut human anterior lens capsule (fs-HALC). Thirty transplantations were performed on aphakic eyes. Recombinant tissue plasminogen activator (rTPA) was used throughout the surgery. The native endothelium was removed by full-surface scraping and central descemetorhexis. The transplantation was performed as a human Descemet's membrane endothelial keratoplasty. Controls included Descemetorhexis only and transplantation of carrier alone. Postoperative follow-up was performed by slit lamp and optical coherence tomography, followed by histology. RESULTS: Controls remained oedematous. No fibrin occurred during surgery. All but three TEEKs adhered immediately. One/6 fs-UTSL and 9/16 fs-HALC cleared perfectly (p = 0.161). All failures could be explained by at least one of the following causes intraoperative bleeding, vitreous prolapsus, early partial detachment, postoperative irido corneal synechiea/angle closure. Presumed immune rejection was observed in three rabbits only after 4 weeks. Immunostaining with anti-human CD166 allowed to perfectly differentiate human cells from rabbit cells. In successful TEEK at 3 or 4 weeks, human cells formed a normal endothelium and started migrating outside the carrier. CONCLUSION: Though the transplantation of a TEEK in rabbits is a complex model with many causes of failure, established procedure including use of rTPA allows reliable preclinical study. In addition, we suggest that fs-HALC might be a potential carrier for TEEK.

Standardized and axially vascularized calcium phosphate-based implants for segmental mandibular defects: A promising proof of concept.

The reconstruction of massive segmental mandibular bone defects (SMDs) remains challenging even today; the current gold standard in human clinics being vascularized bone transplantation (VBT). As alternative to this onerous approach, bone tissue engineering strategies have been widely investigated. However, they displayed limited clinical success, particularly in failing to address the essential problem of quick vascularization of the implant. Although routinely used in clinics, the insertion of intrinsic vascularization in bioengineered constructs for the rapid formation of a feeding angiosome remains uncommon. In a clinically relevant model (sheep), a custom calcium phosphate-based bioceramic soaked with autologous bone marrow and perfused by an arteriovenous loop was tested to regenerate a massive SMD and was compared to VBT (clinical standard). Animals did not support well the VBT treatment, and the study was aborted 2 weeks after surgery due to ethical and animal welfare considerations. SMD regeneration was successful with the custom vascularized bone construct. Implants were well osseointegrated and vascularized after only 3 months of implantation and totally entrapped in lamellar bone after 12 months; a healthy yellow bone marrow filled the remaining space. STATEMENT OF SIGNIFICANCE: Regenerative medicine struggles with the generation of large functional bone volume. Among them segmental mandibular defects are particularly challenging to restore. The standard of care, based on bone free flaps, still displays ethical and technical drawbacks (e.g., donor site morbidity). Modern engineering technologies (e.g., 3D printing, digital chain) were combined to relevant surgical techniques to provide a pre-clinical proof of concept, investigating for the benefits of such a strategy in bone-related regenerative field. Results proved that a synthetic-biologics-free approach is able to regenerate a critical size segmental mandibular defect of 15 cm3 in a relevant preclinical model, mimicking real life scenarii of segmental mandibular defect, with a full physiological regeneration of the defect after 12 months.