Two stage reconstruction with revascularized grafts after resection of retromolar and oropharyngeal carcinoma

Soft palate reconstruction with free jejunum flap: Impact on the velopharyngeal insufficiency

If inadequately reconstructed, large resections of the soft palate inevitably cause velopharyngeal insufficiency, nasal regurgitation and reduce speech intelligibility. A series of 12 free Jejunal flaps are presented, with 28.5 months median follow up (IQR 10.5), with evidence that the flaps provided appropriate secretions and good functionality for speech and resumption of oral intake. A retrospective case series was performed, from 2004 to 2020, including patients diagnosed with palate locally advanced squamous cell carcinoma and reconstructed with free jejunum flap. Twelve patients were included, with mean age of 66 years. No flap loss, thrombosis or infection were recorded. Oral feeding was achieved in all patients, on an average after 36 days from the operation. Speech intelligibility improved by 4 points in a scale 0-10. The thin, pliable, and elastic properties of the free jejunal flap are optimally suited for a functional reconstruction of the three-dimensional palatal defects. With its serous and mucous secretion, the free jejunal flap can lead to early return to solid diet and minimize functional impairment of phonation and speech.

Tissue engineered autologous cartilage-bone grafts for temporomandibular joint regeneration

Joint disorders can be detrimental to quality of life. There is an unmet need for precise functional reconstruction of native-like cartilage and bone tissues in the craniofacial space and particularly for the temporomandibular joint (TMJ). Current surgical methods suffer from lack of precision and comorbidities and frequently involve multiple operations. Studies have sought to improve craniofacial bone grafts without addressing the cartilage, which is essential to TMJ function. For the human-sized TMJ in the Yucatan minipig model, we engineered autologous, biologically, and anatomically matched cartilage-bone grafts for repairing the ramus-condyle unit (RCU), a geometrically intricate structure subjected to complex loading forces. Using image-guided micromilling, anatomically precise scaffolds were created from decellularized bone matrix and infused with autologous adipose-derived chondrogenic and osteogenic progenitor cells. The resulting constructs were cultured in a dual perfusion bioreactor for 5 weeks before implantation. Six months after implantation, the bioengineered RCUs maintained their predefined anatomical structure and regenerated full-thickness, stratified, and mechanically robust cartilage over the underlying bone, to a greater extent than either autologous bone-only engineered grafts or acellular scaffolds. Tracking of implanted cells and parallel bioreactor studies enabled additional insights into the progression of cartilage and bone regeneration. This study demonstrates the feasibility of TMJ regeneration using anatomically precise, autologous, living cartilage-bone grafts for functional, personalized total joint replacement. Inclusion of the adjacent tissues such as soft connective tissues and the TMJ disc could further extend the functional integration of engineered RCUs with the host.

Biomaterials-aided mandibular reconstruction using in vivo bioreactors

Large mandibular defects are clinically challenging to reconstruct due to the complex anatomy of the jaw and the limited availability of appropriate tissue for repair. We envision leveraging current advances in fabrication and biomaterials to create implantable devices that generate bone within the patients themselves suitable for their own specific anatomical pathology. The in vivo bioreactor strategy facilitates the generation of large autologous vascularized bony tissue of customized geometry without the addition of exogenous growth factors or cells. To translate this technology, we investigated its success in reconstructing a mandibular defect of physiologically relevant size in sheep. We fabricated and implanted 3D-printed in vivo bioreactors against rib periosteum and utilized biomaterial-based space maintenance to preserve the native anatomical mandibular structure in the defect site before reconstruction. Nine weeks after bioreactor implantation, the ovine mandibles were repaired with the autologous bony tissue generated from the in vivo bioreactors. We evaluated tissues generated in bioreactors by radiographic, histological, mechanical, and biomolecular assays and repaired mandibles by radiographic and histological assays. Biomaterial-aided mandibular reconstruction was successful in a large superior marginal defect in five of six (83%) sheep. Given that these studies utilized clinically available biomaterials, such as bone cement and ceramic particles, this strategy is designed for rapid human translation to improve outcomes in patients with large mandibular defects.

Periimplant changes in different transplanted soft tissues around loaded endosseous implants in patients after oral tumor surgery

PURPOSE

To examine periimplant reaction of transplanted soft tissues foreign to oral cavity when compared with local gingiva.

METHODS

In 58 oral cancer patients, 210 dental implants were inserted mainly in the mandible after radical surgery and reconstruction. Ninety-six implants penetrated transplants (split skin, mucosal, platysma, pectoralis major, and intestinal) and were compared with 114 implants penetrating local gingiva. Prosthetic treatment consisted of telescopic or bar-retained overdentures or (in case of intestinal grafts) implant-supported fixed prostheses. Follow-up lasted between 30 and 60 months. Plaque index, sulcus bleeding index, pocket probing depth, and width of vestibular-/oral attached mucosa were measured.

RESULTS

Plaque index (before second year; P < 0.01) and pocket probing depth (after first year; P < 0.02-0.04) displayed significant differences with disadvantage for split skin grafts. Sulcus bleeding did not exceed index 1. Attached mucosa had no significant effect on periimplant health.

CONCLUSION

Transplanted extraoral tissues behaved similarly when compared with local gingiva, showing no detrimental effect on periimplant health in oral cancer patients. Split skin and mucosal grafts had worst performance.

Aggrecanases gene inhibition in chondrocytes: a new possible strategy to relieve immune rejection of transplants

Cartilage damaged by trauma or degenerative disease has limited intrinsic potential for repair, due to lack of blood supply. The repair and reconstruction of cartilage defects are severe problems, and many patients are eager to find avenues to these matters. Until now, the number of methods used to repair cartilage defects has increased, but all of these have their own advantages and inconveniences, and do not seem to have been optimized. As the source of autologous cartilage is limited and has a high potential donor site morbidity, it is common practice to transplant allogenic cartilage instead. However, immunological rejection will happen accompanied with allogenic cartilage transplantation, affect the long viability of cartilage and result in the absorption of cartilage. Cartilage is an avascular tissue and its extracellular matrix prevents immunization of the host. The extracellular matrix acts as immunological barrier and makes the cartilage be a poor antigen tissue. So it is important to maintain the stability of cartilage matrix. The main features are the loss of aggrecan after cartilage transplantation surgery and aggrecanases play an important role in the cartilage degradation of aggrecan. We hypothesize that if we inhibit the aggrecanases gene of chondrocytes, make the extracellular matrix aggrecan of chondrocytes increasing and immunological rejection problems will be relieved. Accordingly, this will provide a new method for allogenic and tissue engineering cartilage transplantation and cartilage transplantation will be utilized widely for any clinical treatments.

MHC II gene knockout in tissue engineering may prevent immune rejection of transplants

The repair and reconstruction of tissue defects and organ loss are severe problems, and many patients are eager to find avenues to these matters. Up until now, the number of methods used to repair tissue defects has increased, but all of these have their own advantages and inconveniences, and do not seem to have been optimized. The development of tissue engineering offers new hopes to patients with tissue defects. To regenerate tissues and organs, we first need a source of seed cells. However, the sources of autologous cells are restricted, cell number is small, and xenogenic cells result in immunological rejections. Major histocompatibility complex (MHC) polymorphism is a key factor in tissue grafts. MHC II, in particular, is associated with allogeneic transplantation. We hypothesize that if we knock-out the MHC II gene of mesenchymal stem cells (MSCs) in vitro, these cells would not express MHC II molecules, and rejection problems will be solved. Accordingly, the industrialization of tissue engineering will be feasible, and products of tissue engineering will be utilized widely for any clinical treatments.

Experience with microvascular free flaps in preoperatively irradiated tissue of the oral cavity and oropharynx in 303 patients

This study examined free flap reconstruction of surgical defects of the oral cavity and oropharynx after preoperative radiochemotherapy. Included in this analysis are 303 prospectively followed patients who underwent a multimodal treatment regime for advanced oral and oropharyngeal carcinoma. All patients received preoperative radiochemotherapy (Mitomycin C, 5-FU, 50 Gy), ablative surgery, and primary free flap reconstruction. Patient characteristics, surgical parameters like duration of surgery and ischaemia, size of defect, type of transplant, and clinical outcome parameters like duration of intensive care and hospitalization, type of complications, necessity and type of revision surgery were statistically evaluated. Overall flap success rate was 93.1%. Sixty seven patients required revision and 21 flaps (6.9%) were lost. Overall complication rate was 22.1%. Mean duration of intensive care (DOIC) and duration of overall postoperative hospitalization (DOH) were 11.0+/-9.6 days and 35.9+/-26.3 days, respectively. Flap success and flap related complications after 50 Gy focal radiation dosage were found in a comparable range as in published series of reconstructions in uncompromised tissue.