Intraosseous microdialysis for bone free flap monitoring in head and neck reconstructive surgery: A prospective pilot study.

BACKGROUND: Although some researchers have positioned microdialysis catheters in the soft tissue surrounding bone, the results did not accurately reflect bone metabolism. The present study's objective was to establish the feasibility of microdialysis with a catheter positioned directly in bone. METHODS: Thirty-four patients (19 males, 15 females; median age: 59) were included in a prospective, nonrandomized clinical trial in the Department of Maxillofacial Surgery at Amiens-Picardie University Hospital (Amiens, France). Fibula or iliac crest free flaps were used in reconstructive head and neck surgery (for cancer, osteoradionecrosis, trauma, or ameloblastoma) and monitored with microdialysis catheters positioned in a hole drilled into the bone. Glucose, lactate, pyruvate, and glycerol concentrations were analyzed for 5 days. RESULTS: All catheters were positioned successfully, and thrombosis did not occur during the monitoring. In two patients, an increase in the lactate concentration and a glucose level close to 0 were associated with signs of flap necrosis, with removal on Days 9 and 50. In viable flaps, the mean glucose level was 2.02 mmol/L, the mean lactate level was 8.36 mmol/L, and the mean lactate/pyruvate ratio was 53. Forty percent of the glucose values were below 1 mmol/L, and 50% of the lactate/pyruvate ratio values were above 50-suggesting a specific metabolic pattern because these values would be considered as alert values in soft tissue. CONCLUSION: Monitoring bone free flaps with intraosseous microdialysis is feasible. This technique specifically assesses bone viability, and further studies are now necessary to define the alert values in bone.

Endosteal blood supply of the mandible: anatomical study of nutrient vessels in the condylar neck accessory foramina.

PURPOSE: In the mandible, the condylar neck vascularization is commonly described as mainly periosteal; while the endosteal contribution is still debated, with very limited anatomical studies. Previous works have shown the contribution of nutrient vessels through accessory foramina and their contribution in the blood supply of other parts of the mandible. Our aim was to study the condylar neck's blood supply from nutrient foramina. METHODS: Six latex-injected heads were dissected and two hundred mandibular condyles were observed on dry mandibles searching for accessory bone foramina. RESULTS: Latex-injected dissections showed a direct condylar medular arterial supply through foramina. On dry mandibles, these foramina were most frequently observed in the pterygoid fovea in 91% of cases. However, two other accessory foramina areas were identified on the lateral and medial sides of the mandibular condylar process, confirming the vascular contribution of transverse facial and maxillary arteries. CONCLUSIONS: The maxillary artery indeed provided both endosteal and periosteal blood supply to the condylar neck, with three different branches: an intramedullary ascending artery (arising from the inferior alveolar artery), a direct nutrient branch and some pterygoid osteomuscular branches.

Whole exome sequencing identifies mutations in 10% of patients with familial non-syndromic cleft lip and/or palate in genes mutated in well-known syndromes.

BACKGROUND: Oral clefts, that is, clefts of the lip and/or cleft palate (CL/P), are the most common craniofacial birth defects with an approximate incidence of ~1/700. To date, physicians stratify patients with oral clefts into either syndromic CL/P (syCL/P) or non-syndromic CL/P (nsCL/P) depending on whether the CL/P is associated with another anomaly or not. In general, patients with syCL/P follow Mendelian inheritance, while those with nsCL/P have a complex aetiology and, as such, do not adhere to Mendelian inheritance. Genome-wide association studies have identified approximately 30 risk loci for nsCL/P, which could explain a small fraction of heritability. METHODS: To identify variants causing nsCL/P, we conducted whole exome sequencing on 84 individuals with nsCL/P, drawn from multiplex families (n=46). RESULTS: We identified rare damaging variants in four genes known to be mutated in syCL/P: TP63 (one family), TBX1 (one family), LRP6 (one family) and GRHL3 (two families), and clinical reassessment confirmed the isolated nature of their CL/P. CONCLUSION: These data demonstrate that patients with CL/P without cardinal signs of a syndrome may still carry a mutation in a gene linked to syCL/P. Rare coding and non-coding variants in syCL/P genes could in part explain the controversial question of 'missing heritability' for nsCL/P. Therefore, gene panels designed for diagnostic testing of syCL/P should be used for patients with nsCL/P, especially when there is at least third-degree family history. This would allow a more precise management, follow-up and genetic counselling. Moreover, stratified cohorts would allow hunting for genetic modifiers.

Vascular anatomy of the free fibula flap including the lateral head of the soleus muscle applied to maxillo-mandibular reconstruction.

PURPOSE: Initially described by Baudet in 1982, the fibula flap including the lateral head of the soleus muscle allows a one-stage reconstruction for large maxillo-mandibular defects. The aim of this study was to evaluate the number of muscular branches destined to the soleus muscle and their distance from the origin of the fibular artery, to assess the vascular anatomy of the free fibula flap including the lateral head of the soleus muscle applied to maxillo-mandibular reconstruction. METHODS: We performed a cadaveric anatomic study on ten lower limbs, and a CT angiography anatomic study on 38 legs. The number of soleus branches originating from the fibular artery, and the distance between the origin of the fibular artery and each of the identified branches were measured. RESULTS: The number of soleus branches destined to the lateral head of the soleus muscle is variable, with in our study 1-3 branches found. Soleus branches destined to the lateral head of the soleus muscle emerged at a distance ranging between 0 and 2.9 cm (mean value = 1.82 cm) from the origin of the fibular artery in 40% of cases, between 3 and 5.9 cm (mean value = 4.27 cm) from the origin of the fibular artery in 37% of cases, and was at a distance of 6 cm or more (mean value = 6.93 cm) from the origin of the fibular artery in 20% of cases. CONCLUSIONS: An origin of the soleus vessels in close proximity to the origin of the fibular artery represents the main limitation of this flap, the length of the remaining fibular pedicle making it difficult to achieve secure anastomosis in the cervical area. The vascular distribution of the proximal part of the lateral head of the soleus muscle being segmental, it is possible to lengthen the flap pedicle ligating the most proximal soleus branches originating from the fibular artery.

Unmasking familial CPX by WES and identification of novel clinical signs.

Mutations in the T-Box transcription factor gene TBX22 are found in X-linked Cleft Palate with or without Ankyloglossia syndrome (CPX syndrome). In addition to X-linked inheritance, ankyloglossia, present in the majority of CPX patients, is an important diagnostic marker, but it is frequently missed or unreported, as it is a "minor" feature. Other described anomalies include cleft lip, micro and/or hypodontia, and features of CHARGE syndrome. We conducted whole exome sequencing (WES) on 22 individuals from 17 "a priori" non-syndromic cleft lip and/or cleft palate (CL/P) families. We filtered the data for heterozygous pathogenic variants within a set of predefined candidate genes. Two canonical splice-site mutations were found in TBX22. Detailed re-phenotyping of the two probands and their families unravelled orofacial features previously not associated with the CPX phenotypic spectrum: choanal atresia, Pierre-Robin sequence, and overgrowths on the posterior edge of the hard palate, on each side of the palatal midline. This study emphasizes the importance of WES analysis in familial CLP cases, combined with deep (reverse) phenotyping in "a priori" non-syndromic clefts.

Multicenter prospective micro-costing study evaluating mandibular free-flap reconstruction.

Free-flap mandibular reconstruction is a highly specialized procedure associated with severe complications necessitating re-interventions and re-hospitalizations. This surgery is expensive in terms of health workers' time, equipment, medical devices and drugs. Our main objective was to assess the direct hospital cost generated by osseocutaneous free-flap surgery in a multicentric prospective micro-costing study. Direct medical costs evaluated from a hospital perspective were assessed using a micro-costing method from the first consultation with the surgeon until the patient returns home, thus confirming the success or failure of the free-flap procedure. The mean total cost for free-flap intervention was 34,009€ (5151-119,604€), the most expensive item being the duration of hospital bed occupation, representing 30-90% of the total cost. In the event of complications, the mean cost increased by 77.3%, due primarily to hospitalization in ICU and the conventional unit. This surgery is effective and provides good results but remains highly complex and costly.

Reconstructive flap surgery in head and neck cancer patients: an interdisciplinary view of the challenges encountered by radiation oncologists in postoperative radiotherapy.

Background: Major advances have been made in reconstructive surgery in the last decades to reduce morbidity in head and neck cancer. Flaps are now present in 80% of patients with oral cavity cancer to cover anatomic, functional, and cosmetic needs. However, gaps in interdisciplinary innovation transfer from surgery to postoperative radiotherapy (poRT) remain challenging. We aimed to provide an interdisciplinary view of the challenges encountered by radiation oncologists in planning head and neck postoperative radiotherapy. Methods: A systematic and critical review was conducted to address areas of optimization in surgery and radiology that may be relevant to poRT. Results: Despite extensive surgical literature on flap techniques and salvage surgery, 13 retrospective series were identified, where flap outcomes were indirectly compared between surgery alone or poRT. These low-evidence studies suggest that radiotherapy accelerates flap atrophy, fibrosis, and osteoradionecrosis and deteriorates functional outcomes. Preliminary evidence suggests that tumor spread occurs at the flap-tissue junction rather than in the flaps. One prospective 15-patient study showed 31.3% vs. 39.2% flap volume reduction without or with poRT. In an international consensus, experts recognized the needs for optimized flap-sparing poRT against flap-related functional deterioration and bone damage. CT, MRI, and PET-CT modalities show potential for the delineation of the junction area between native tissues and flap for flap segmentation and to characterize flap-specific changes quantitatively and correlate them with patterns of relapse or complications. Conclusion: Flap management in poRT is insufficiently documented, but poRT seems to damage flaps. Current gaps in knowledge underscore the need for prospective flap assessment and interdisciplinary trials investigating flap morbidity minimization by flap-sparing poRT planning.

Impact of the COVID-19 Pandemic on Head and Neck Cancer Management: The Experience of the Maxillo-Facial Surgery Department of a French Regional Referral Center in a High-Incidence Area.

Background: Cancer patients are at a high risk of complications in cases of infection, and head and neck cancers (HNC) are no exception. Since late 2019, SARS-CoV-2 has caused a global health crisis, with high rates and severe forms of the disease in cancer patients. Hospitalization, surgery and radiotherapy were rapidly described as increasing the risk of infection. Since March 2020, the Amiens University Hospital (France) has been taking care of COVID-19 patients while its maxillofacial surgery department managed HNC patients without interruption, even during lockdown periods. However, many questions concerning the impact on patient care were still pending. The aim of this study is to describe HNC management in our center during the first epidemic peak and to evaluate the impact of containment measures on patient treatment. Methods: We retrospectively included 44 HNC patients treated in our department between 1 March and 31 August 2020. Two groups were defined according to the period of care: lockdown (March to May) and lighter restrictions (June to August). Results: The results show typical epidemiological characteristics, maintained management times and non-downgraded procedures. Conclusions: Thus, during the first epidemic peak, continuity of care and patients' safety could be ensured thanks to adequate means, adapted procedures and an experienced surgical team.

[Issues and implementation of postoperative radiotherapy after flap reconstructive surgery in head and neck cancers]. / Enjeux et mise en œuvre de radiothérapie postopératoire après chirurgie reconstructrice avec lambeau dans les cancers de la tête et du cou.

The management of head and neck cancers is multidisciplinary, often relying on the use of combined treatments to maximize the chances of cure. Combined treatments are however also responsible for cumulative side effects. The aim of reconstructive surgery with a flap is to restore a function lost with the loss of substance from the tumor resection. However, changes in reconstructive surgery have impact of postoperative radiotherapy planning. The optimization of imaging protocols for radiotherapy planning should make it possible to identify postoperative changes and to distinguish flaps from surrounding native tissues to delineate the flaps and document the spontaneous evolution of these flaps or dose-effect relationships in case of radiotherapy. Such changes include atrophy, fibrosis of soft tissue flaps and osteoradionecrosis of bone flaps. Radiotherapy optimization also involves standardization of the definition of target volumes in situations where a flap is present, a situation that is increasingly common in routine care. This evolution of practice, beyond the essential multidisciplinary consultation meetings defining treatment indications, requires a close radio surgical collaboration with respect to technical aspects of the two disciplines. Doing so, anticipation of relapse and toxicity profiles could possibly lead to propose strategies for personalized de-escalation of multimodal treatments through interdisciplinary trials.

The Facial Graft: A Graft of Emotions? (About the Reanimation of the Facial Allotransplantation).

Although there have been numerous scientific papers reporting on composite allotransplantation of the face, few have been about assessment and evolution of the functional benefit for patients in terms of soft tissue mobility, movement coordination, and face expressions, even fewer on the choice of the surgical procedures to restore motricity. On some videos and interviews, it is possible to analyze significative motricity. Of course that has been voluntary motricity, not emotional motricity. The data confirmed that the result on the complexity of the expression of the face is not great, providing opportunity to reflect on the question of nerve regeneration.

Evaluation of a Granular Bone Substitute for Bone Regeneration Using an Optimized In Vivo Alveolar Cleft Model.

Alveolar cleft is a common congenital deformity that requires surgical intervention, notably using autologous bone grafts in young children. Bone substitutes, in combination with mesenchymal stem cells (MSCs), have shown promise in the repair of these defects. This study aimed to evaluate the regenerative capabilities of a granular bone substitute using an optimized alveolar cleft model. Thirty-six rats underwent a surgical procedure for the creation of a defect filled with a fragment of silicone. After 5 weeks, the silicone was removed and the biomaterial, with or without Wharton's jelly MSCs, was put into the defect, except for the control group. The rats underwent µCT scans immediately and after 4 and 8 weeks. Analyses showed a statistically significant improvement in bone regeneration in the two treatment groups compared with control at weeks 4 and 8, both for bone volume (94.64% ± 10.71% and 91.33% ± 13.30%, vs. 76.09% ± 7.99%) and mineral density (96.13% ± 24.19% and 93.01% ± 27.04%, vs. 51.64% ± 16.51%), but without having fully healed. This study validates our optimized alveolar cleft model in rats, but further work is needed to allow for the use of this granular bone substitute in the treatment of bone defects.

Evaluation of Proton MR Spectroscopy for the Study of the Tongue Tissue in Healthy Subjects and Patients With Tongue Squamous Cell Carcinoma: Preliminary Findings.

Purpose: To noninvasively assess spectroscopic and metabolic profiles of healthy tongue tissue and in an exploratory objective in nontreated and treated patients with tongue squamous cell carcinoma (SCC). Methods: Fourteen healthy subjects (HSs), one patient with nontreated tongue SCC (NT-SCC), and two patients with treated tongue SCC (T-SCC) underwent MRI and single-voxel proton magnetic resonance spectroscopy (1H-MRS) evaluations (3 and 1.5T). Multi-echo-times 1H-MRS was performed at the medial superior part (MSP) and the anterior inferior part (AIP) of the tongue in HS, while 1H-MRS voxel was placed at the most aggressive part of the tumor for patients with tongue SCC. 1H-MRS data analysis yielded spectroscopic metabolite ratios quantified to total creatine. Results: In HS, compared to MSP and AIP, 1H-MRS spectra revealed higher levels of creatine, a more prominent and well-identified trimethylamine-choline (TMA-Cho) peak. However, larger prominent lipid peaks were better differentiated in the tongue MSP. Compared to HS, patients with NT-SCC exhibited very high levels of lipids and relatively higher values of TMA-Cho peak. Interestingly, patients with T-SCC showed almost nonproliferation activity. However, high lipids levels were measured, although they were relatively lower than lipids levels measured in patients with NT-SCC. Conclusion: The present study demonstrated the potential use of in-vivo 1H-MRS to noninvasively assess spectroscopic and metabolic profiles of the healthy tongue tissue in a spatial location-dependent manner. Preliminary results revealed differences between HS and patients with tongue NT-SCC as well as tongue T-SCC, which should be confirmed with more patients. 1H-MRS could be included, in the future, in the arsenal of tools for treatment response evaluation and noninvasive monitoring of patients with tongue SCC.

Efficiency of advanced-PRF usage in the treatment of alveolar cleft with iliac bone graft: A retrospective study.

The aim of this study was to evaluate the efficiency of a new alveolar bone grafting protocol using advanced-PRF (a-PRF) by comparing the volumes of newly formed bone after a bone graft combining autogenous iliac crest bone with either PRF or a-PRF. Patients presenting with unilateral or a bilateral alveolar cleft were included retrospectively in two groups: one group was grafted using cancellous iliac crest bone with PRF (PRF group), whereas for the other group the same procedure was followed using a-PRF (a-PRF group). CBCT scans were performed 3 months preoperatively and 6 months postoperatively. The volume of newly formed bone was measured by subtracting the postoperative cleft volume from the preoperative cleft volume. The mean volume of newly formed bone was compared between the two groups using Student's t-test. Twenty-four patients were included, with 12 allocated to each group. Forty-eight CBCT scans were analyzed. The mean volume of newly formed bone was 0.29 (±0.09) cm3 in the a-PRF group, versus 0.20 (±0.08) cm3 in the PRF group (Student's t-test, p = 0.024). The percentage of newly formed bone was 60.4 (±10.4) % in the a-PRF group versus 51.4 (±18.4) % in the PRF group (Student's t-test, p = 0.165). Our study demonstrated improved bone regeneration in the a-PRF group. While bearing in mind the limitations of this study, the a-PRF procedure should be adopted in cleft bone grafting whenever possible.

Donor variability alters differentiation and mechanical cohesion of tissue-engineered constructs with human endothelial/MSC co-culture.

To move towards clinical applications, tissue engineering (TE) should be validated with human primary cells and offer easy connection to the native vascularisation. Based on a sheet-like bone substitute developed previously, we investigated a mesenchymal stem cells/endothelial cells (MSCs/ECs) coculture to enhance pre-vascularisation. Using MSCs from six independent donors whose differentiation potential was assessed towards two lineages, we focused on donor variability and cell crosstalk regarding bone differentiation. Coculture was performed on calcium phosphate granules in a specific chamber during 1 month. MSCs were seeded first then ECs were added after 2 weeks, with respective monocultures as control groups. Cell viability and organisation (fluorescence, electronic microscopy), differentiation (ALP staining/activity, RT-qPCR) and mechanical cohesion were analysed. Adaptation of the protocol to coculture was validated (high cell viability and proliferation). Activity and differentiation showed strong trends towards synergistic effects between cell types. MSCs reached early mineralisation stage of maturation. The delayed addition of ECs allowed for their attachment on developed MSCs' matrix. The main impact of donor variability could be here the lack of cell proliferation potential with some donors, leading to low differentiation and mechanical cohesion and therefore absence of sheet-like shape successfully obtained with others. We suggest therefore adapting protocols to cell proliferation potentials from one batch of cells to the other in a patient-specific approach.

Outcomes 18 months after the first human partial face transplantation.

BACKGROUND: We performed the first human partial face allograft on November 27, 2005. Here we report outcomes up to 18 months after transplantation. METHODS: The postsurgical induction immunosuppression protocol included thymoglobulins combined with tacrolimus, mycophenolate mofetil, and prednisone. Donor hematopoietic stem cells were infused on postoperative days 4 and 11. Sequential biopsy specimens were taken from a sentinel skin graft, the facial skin, and the oral mucosa. Functional progress was assessed by tests of sensory and motor function performed monthly. Psychological support was provided before and after transplantation. RESULTS: Sensitivity to light touch, as assessed with the use of static monofilaments, and sensitivity to heat and cold had returned to normal at 6 months after transplantation. Motor recovery was slower, and labial contact allowing complete mouth closure was achieved at 10 months. Psychological acceptance of the graft progressed as function improved. Rejection episodes occurred on days 18 and 214 after transplantation and were reversed. A decrease in inulin clearance led to a change in immunosuppressive regimen from tacrolimus to sirolimus at 14 months. Extracorporeal photochemotherapy was introduced at 10 months to prevent recurrence of rejection. There have been no subsequent rejection episodes. At 18 months, the patient is satisfied with the aesthetic result. CONCLUSIONS: In this patient who underwent the first partial face transplantation, the functional and aesthetic results 18 months after transplantation are satisfactory.

Use of an occlusal splint and intraoperative imaging with an intraoral approach in the management of mandibular subcondylar fractures.

INTRODUCTION: To evaluate the feasibility of safely managing subcondylar fractures using an original surgical procedure combining an intraoral approach, the use of a custom-made occlusal overlay splint, and intraoperative imaging. MATERIALS AND METHODS: Condylar fragment was freed from surrounding soft tissues, was laterally exposed to the ramus, and a miniplate was fixed in place for osteosynthesis. An overlay splint maintaining the dental occlusion was used to facilitate reduction and stabilization during fixation. Intraoperative monitoring by cone-beam computed tomography (CBCT) was performed before completing the fixation. RESULTS: Between November 2018 and June 2019, 10 patients were treated using this procedure. The median length of the proximal condylar fragment was 29 mm (range 24-39 min). Five patients had an associated mandibular fracture. The median duration of the condylar fracture surgery was 54.5 min (range 38-79 min). All patients had satisfactory reduction and osteosynthesis with no complications. CONCLUSION: It is feasible to safely manage subcondylar fractures with this surgical procedure that could facilitate open reduction using intraoral approaches. Occlusal splints maintain downward pressure on the rami bilaterally and symmetrically, helping to anatomically reposition condylar process fractures. Intraoperative imaging is used to monitor this step.

An Alginate-Based Hydrogel with a High Angiogenic Capacity and a High Osteogenic Potential.

In bone tissue engineering, autologous cells are combined with osteoconductive scaffolds and implanted into bone defects. The major challenge is the lack of post-implantation vascular growth into biomaterial. The objective of the present study was to develop a new alginate-based hydrogel that enhances the regeneration of bone defects after surgery. The viability of human bone marrow-derived mesenchymal stem cells (BM-MSCs) or human endothelial cells (ECs) cultured alone or together on the hydrogel was analyzed for 24 and 96 h. After seeding, the cells self-assembled and aggregated to form clusters. For functional validation, empty or cellularized hydrogel matrices were implanted ectopically at subcutaneous sites in nude mice. After 2 months, the matrices were explanted. Transplanted human cells were present, and we observed vessels expressing human von Willebrand factor (resulting from the incorporation of transplanted ECs into neovessels and/or the differentiation of BM-MSCs into ECs). The addition of BM-MSCs improved host vascularization and neovessel formation from human cells, relative to ECs alone. Although we did not observe bone formation, the transplanted BM-MSCs were able to differentiate into osteoblasts. This new biomaterial provided an appropriate three-dimensional environment for transplanted cells and has a high angiogenic capacity and an osteogenic potential.

The combination of a poly-caprolactone/nano-hydroxyapatite honeycomb scaffold and mesenchymal stem cells promotes bone regeneration in rat calvarial defects.

Bone tissue engineering goes beyond the limitations of conventional methods of treating bone loss, such as autograft-induced morbidity and a lack of integration for large grafts. Novel biomimicry approaches (using three-dimensional [3D] electrospinning and printing techniques) have been designed to offer the most appropriate environment for cells and thus promote bone regeneration. In the present study, we assessed the bone regeneration properties of a composite 3D honeycomb structure from the electrostatic template-assisted deposition process by an alternate deposition of electrospun polycaprolactone (PCL) nanofibers and electrosprayed hydroxyapatite nanoparticles (nHA) on a honeycomb micropatterned substrate. We first confirmed the cytocompatibility of this honeycomb PCL-nHA scaffold in culture with bone marrow-derived mesenchymal stem cells (BM-MSCs). The scaffold was then implanted (alone or with seeded MSCs) for 2 months in a rat critical-sized calvarial defect model. The observation of new bone synthesis in situ (monitored using microcomputed tomography every 2 weeks and a histological assessment upon extraction) demonstrated that the honeycomb PCL-nHA scaffold was osteoconductive. Moreover, the combination of the scaffold with BM-MSCs was associated with significantly greater bone volume and mineralized regeneration during the 2-month experiment. The combination of the biomimetic honeycomb PCL-nHA scaffold with patient mesenchymal stem cells might therefore have great potential for clinical applications and specifically in maxillofacial surgery.

Functional Validation of a New Alginate-based Hydrogel Scaffold Combined with Mesenchymal Stem Cells in a Rat Hard Palate Cleft Model.

BACKGROUND: One of the major difficulties in cleft palate repair is the requirement for several surgical procedures and autologous bone grafting to form a bony bridge across the cleft defect. Engineered tissue, composed of a biomaterial scaffold and multipotent stem cells, may be a useful alternative for minimizing the non-negligible risk of donor site morbidity. The present study was designed to confirm the healing and osteogenic properties of a novel alginate-based hydrogel in palate repair. METHODS: Matrix constructs, seeded with allogeneic bone marrow-derived mesenchymal stem cells (BM-MSCs) or not, were incorporated into a surgically created, critical-sized cleft palate defect in the rat. Control with no scaffold was also tested. Bone formation was assessed using microcomputed tomography at weeks 2, 4, 8, and 12 and a histologic analysis at week 12. RESULTS: At 12 weeks, the proportion of bone filling associated with the use of hydrogel scaffold alone did not differ significantly from the values observed in the scaffold-free experiment (61.01% ± 5.288% versus 36.91% ± 5.132%; p = 0.1620). The addition of BM-MSCs stimulated bone formation not only at the margin of the defect but also in the center of the implant. CONCLUSIONS: In a relevant in vivo model of cleft palate in the rat, we confirmed the alginate-based hydrogel's biocompatibility and real advantages for tissue healing. Addition of BM-MSCs stimulated bone formation in the center of the implant, demonstrating the new biomaterial's potential for use as a bone substitute grafting material for cleft palate repair.