Decellularized Whole-Organ Pre-vascularization: A Novel Approach for Organogenesis.

Introduction: Whole-organ decellularization is an attractive approach for three-dimensional (3D) organ engineering. However, progress with this approach is hindered by intra-vascular blood coagulation that occurs after in vivo implantation of the re-cellularized scaffold, resulting in a short-term graft survival. In this study, we explored an alternative approach for 3D organ engineering through an axial pre-vascularization approach and examined its suitability for pancreatic islet transplantation. Methods: Whole livers from male Lewis rats were decellularized through sequential arterial perfusion of detergents. The decellularized liver scaffold was implanted into Lewis rats, and an arteriovenous bundle was passed through the scaffold. At the time of implantation, fresh bone marrow preparation (BM; n = 3), adipose-derived stem cells (ADSCs; n = 4), or HBSS (n = 4) was injected into the scaffold through the portal vein. After 5 weeks, around 2,600 islet equivalents (IEQs) were injected through the portal vein of the scaffold. The recipient rats were rendered diabetic by the injection of 65 mg/kg STZ intravenously 1 week before islet transplantation and were followed up after transplantation by measuring the blood glucose and body weight for 30 days. Intravenous glucose tolerance test was performed in the cured animals, and samples were collected for immunohistochemical (IHC) analyses. Micro-computed tomography (CT) images were obtained from one rat in each group for representation. Results: Two rats in the BM group and one in the ADSC group showed normalization of blood glucose levels, while one rat from each group showed partial correction of blood glucose levels. In contrast, no rats were cured in the HBSS group. Micro-CT showed evidence of sprouting from the arteriovenous bundle inside the scaffold. IHC analyses showed insulin-positive cells in all three groups. The number of von-Willebrand factor-positive cells in the islet region was higher in the BM and ADSC groups than in the HBSS group. The number of 5-bromo-2'-deoxyuridine-positive cells was significantly lower in the BM group than in the other two groups. Conclusions: Despite the limited numbers, the study showed the promising potential of the pre-vascularized whole-organ scaffold as a novel approach for islet transplantation. Both BM- and ADSCs-seeded scaffolds were superior to the acellular scaffold.

Disfiguring high-flow cervicofacial arteriovenous malformations.

Arteriovenous malformations (AVMs) are congenital vascular anomalies resulting from defects in angiogenesis. Approximately 40% of AVMs go undetected after birth and only experience the delayed clinical onset of symptoms in adulthood. AVMs are rare, representing only 1.5% of all vascular anomalies. The most common sites for the aberrant vascular nidus are the oral cavity and maxillofacial region, which represent 50% of the cases. AVMs are the most challenging and life-threatening form of vascular malformation. Exsanguination, thrombus detachment and embolization are the most hazardous operative risks. Small case series revealed a 75% recurrence rate during a 5-year follow-up, which adds another layer of complexity to their management. Large lesions in the head and neck cause deformation to the patient and present a challenge to the surgeon during their excision among vital structures and reconstruction of the 3D complex defects.

The challenging case of a primigravid Bedouin woman with a dormant neck nodule that grew explosively during her pregnancy.

A Desmoid tumor in the neck is a rare tumor in an even more unusual site. Our patient was an 18-year-old primigravid Bedouin woman from northwest Egypt. She presented with a dormant neck nodule that grew explosively during her first pregnancy and stopped abruptly after delivery. The presentation was confusing at first, as the fixation of the tumor to the underlying tissues implied a malignancy, while a 1-year history of non-metastasis alluded to a benign process. Pre-operative tissue diagnosis revealed an Estrogen receptor-expressing desmoid tumor. Desmoid tumors are indeed locally invasive with no metastatic potential, but they tend to recur and grow during high-estrogen states. This report aims to increase awareness of peripartum Desmoid tumors, as well as discuss the surgical-site, psychological and socioeconomic challenges in the peculiar case of this Bedouin woman, and our recommendations after this experience and literature review.

Independent predisposing factors for subcutaneous and deep wound collection after total thyroidectomy, a prospective cohort study.

BACKGROUND: The literature contains diverse and sometimes contradicting results about wound seroma following thyroidectomy. This is probably due to the subjective clinical estimation of seroma, or due to failure to differentiate between the occurrence of subcutaneous (SC) and deep wound collections. This work aimed at objectively investigating the factors affecting subcutaneous and deep wound seroma after thyroidectomy. METHODS: The relation between various operative and clinico-pathological factors and the collection formation was prospectively analyzed in a cohort of 100 patients after conventional thyroidectomy. Wound seroma was assessed clinically and via high-resolution ultrasonography at 24 h, 48 h and two weeks postoperatively. Sonographically detected collections were expressed as SC and/or deep wound collections according to the relation to strap muscles. RESULTS: Operative duration was the only independent factor significantly affecting the incidence of clinical seroma. Older patients (>40ys) showed significantly larger volumes of early SC collections. Early postoperative pain was significantly related to drain insertion, to the occurrence of clinical seroma and to the volume of SC collections.Sonographically, suction drains and shorter operative durations resulted in significantly less amount of deep collections. Suction drains did not result in less amount of SC collections or in a lower incidence of clinical seroma. CONCLUSIONS: Operative duration is the only independent factor significantly related to clinically-detected postoperative seroma with its subsequent postoperative pain. Especially in elderly patients, a flapless technique would be recommended as these patients developed larger volumes of SC collections with subsequent higher pain scores, even if seroma was not clinically detected.

Rapid hepatic perfusion decellularization: technique and critique.

BACKGROUND: Organ shortage facing the increasing success of liver transplantation has provoked research into the utilization of animal organs for clinical transplantation. The technique of whole-organ decellularization aims at the removal of the antigenic cellular content, thus evading the immune rejection cascade and the production of complex three-dimensional extracellular matrices of the entire organs with preservation of their intrinsic vascular networks rendering them transplantable. The aim of this study was the production of decellularized rabbit liver matrices by applying a simple, rapid perfusion decellularization technique and their characterization (both qualitatively and quantitatively). MATERIALS AND METHODS: Decellularization of the caudate hepatic lobes of New Zealand white rabbits (n = 22) was achieved through sequential perfusion of the portal venous system with deionized water, 0.8% Triton X-100 and 0.8% sodium dodecyl sulphate (SDS). Decellularized specimens were characterized both qualitatively (histology, fluoroscopy, corrosion casting and scanning electron microscopy) and quantitatively (total collagen assay [colorimetric] and total DNA assay [Hoechst 33258]). A Student's t-test was used to compare quantitative laboratory results before and after decellularization. A probability (P) value of <0.05 was considered significant. RESULTS: Effective decellularization was achieved as proven by histology and quantitative assessment (DNA remnants <1.5%, P = 0.0009), while preserving 68% of the total collagen content (P = 0.003). Portal vascular network integrity was confirmed by fluoroscopy and corrosion casting. Scanning electron microscopy also confirmed the preservation of the three-dimensional architecture. CONCLUSIONS: Liver perfusion decellularization technique using both 0.8% Triton X-100 and 0.8% SDS is a simple and rapid technique, yielding efficiently decellularized liver matrices preserving their vascular integrity, 3D architecture and 68% of total collagen content.

Axially vascularised mandibular constructs: Is it time for a clinical trial?

Applying regenerative therapies in the field of cranio-maxillofacial reconstruction has now become a daily practice. However, regeneration of challenging or irradiated bone defects following head and neck cancer is still far beyond clinical application. As the key factor for sound regeneration is the development of an adequate vascular supply for the construct, the current modalities using extrinsic vascularization are incapable of regenerating such complex defects. Our group has recently introduced the intrinsic axial vascularization technique to regenerate mandibular defects using the arteriovenous loop (AVL). The technique has shown promising results in terms of efficient vascularization and bone regeneration at the preclinical level. In this article, we have conducted a narrative literature review about using the AVL to vascularize tissue-engineering constructs at the preclinical level. We have also conducted a systematic literature review about applying the technique of axial vascularization in the field of craniofacial regeneration. The versatility of the technique and the possible challenges are discussed, and a suggested protocol for the first clinical trial applying the AVL technique for mandibular reconstruction is also presented.

Enhancing mandibular bone regeneration and perfusion via axial vascularization of scaffolds.

OBJECTIVE: Reconstruction of large and complex bone segments is a challenging problem facing maxillofacial surgery. The majority of current regenerative approaches rely on extrinsic vascularization, which is deficient after cancer ablation and irradiation. The aim of the study was to investigate the efficacy of intrinsic axial vascularization of synthetic bone scaffolds in the management of critical-size mandibular defects. MATERIALS AND METHODS: Scaffold-guided mandibular regeneration in two groups of adult male goats was compared. Only the scaffolds of the second group were axially vascularized via in situ embedding of an arteriovenous loop through microsurgical anastomosis of facial vessels. After 6 months of follow up, both groups were compared through radiological, biomechanical, histological and histomorphometric analysis. RESULTS: The axially vascularized constructs have showed significantly more central vascularization (p = 0.021) and markedly enhanced central bone formation (p = 0.08). The biomechanical characteristics were enhanced, but the difference between both groups was not statistically significant (p = 0.98). CONCLUSIONS: Axially vascularized synthetic mandibular grafts show better vascularization at their central regions, permitting more efficient bone regeneration. CLINICAL RELEVANCE: The encouraging results of the proposed technique could be of benefit in optimizing the reconstruction of large critical-size bone defects.

Mandibular reconstruction using an axially vascularized tissue-engineered construct.

BACKGROUND: Current reconstructive techniques for continuity defects of the mandible include the use of free flaps, bone grafts, and alloplastic materials. New methods of regenerative medicine designed to restore tissues depend mainly on the so-called extrinsic neovascularization, where the neovascular bed originates from the periphery of the construct. This method is not applicable for large defects in irradiated fields. METHODS: We are introducing a new animal model for mandibular reconstruction using intrinsic axial vascularization by the Arterio-Venous (AV) loop. In order to test this model, we made cadaveric, mechanical loading, and surgical pilot studies on adult male goats. The cadaveric study aimed at defining the best vascular axis to be used in creating the AV loop in the mandibular region. Mechanical loading studies (3 points bending test) were done to ensure that the mechanical properties of the mandible were significantly affected by the designed defect, and to put a base line for further mechanical testing after bone regeneration. A pilot surgical study was done to ensure smooth operative and post operative procedures. RESULTS: The best vascular axis to reconstruct defects in the posterior half of the mandible is the facial artery (average length 32.5 ± 1.9 mm, caliber 2.5 mm), and facial vein (average length 33.3 ± 1.8 mm, caliber 2.6 mm). Defects in the anterior half require an additional venous graft. The defect was shown to be significantly affecting the mechanical properties of the mandible (P value 0.0204). The animal was able to feed on soft diet from the 3rd postoperative day and returned to normal diet within a week. The mandible did not break during the period of follow up (2 months). CONCLUSIONS: Our model introduces the concept of axial vascularization of mandibular constructs. This model can be used to assess bone regeneration for large bony defects in irradiated fields. This is the first study to introduce the concept of axial vascularization using the AV loop for angiogenesis in the mandibular region. Moreover, this is the first study aiming at axial vascularization of synthetic tissue engineering constructs at the site of the defect without any need for tissue transfer (in contrast to what was done previously in prefabricated flaps).

The extended latissimus dorsi flap option in autologous breast reconstruction: A report of 14 cases and review of the literature.

BACKGROUND: Autologous breast reconstruction using the extended latissimus dorsi flap has been infrequently reported. In the current study, the authors are reporting their own clinical experience with this method. A review of the literature is also discussed. MATERIALS AND METHODS: Over a three year period, 14 patients underwent breast reconstruction using the extended latissimus dorsi (LD) flap. Patients with small to medium sized breasts were selected. The age of the patients ranged from 29 to 42 years with a follow-up period ranging from six to 18 months. The indications, flap-related complications and donor site morbidity and aesthetic results were evaluated. RESULTS: The main indication to use the flap was dorsal donor site preference by patients. The remaining patients were either not suitable for a flap from the abdomen or wished to get pregnant and were offered the dorsal donor site. Neither total nor partial flap loss was recorded but donor site morbidity was mainly due to seroma, which was treated conservatively in all patients, except for one who required surgery. Another two patients suffered from wound breakdown and distal necrosis of the back flaps. Mild contour deformity was also noted on the back of all patients but caused no major concern. Indeed, the overall patient satisfaction was very high. CONCLUSION: The extended LD flap proved to be a good option for autologous breast reconstruction in selected patients. Patients should be warned of the potential for seroma and mild contour back deformity.

Soft tissue sarcoma of the upper extremity: a 5-year experience at two institutions emphasizing the role of soft tissue flap reconstruction.

BACKGROUND: The objective of this study was to define the impact of soft tissue flap reconstruction on multimodality therapy for patients with soft tissue sarcomas of the upper extremity. Treatment standards continue to evolve for these patients, and, with multimodality therapy, most of them are candidates for limb-preserving surgery. Consequently, the role of soft tissue flap reconstruction is expanding. METHODS: A review was conducted of 100 consecutive patients with soft tissue sarcomas of the upper extremity who underwent surgery at several institutions between 1992 and 1997. RESULTS: Seventy-one patients underwent direct closure of defects after tumor resection, and 29 patients required soft tissue reconstruction with flaps. These groups were similar in most respects, except that 52% of the patients who required soft tissue reconstruction presented with recurrent disease (P = 0.0004), and 79% of them had tumors measuring > 5 cm in greatest dimension (P = 0.0003). The patients who required flap reconstruction had larger skin deficits after undergoing tumor resection (140 cm2) compared with the patients who had wounds that were managed by direct closure (40 cm2; P < 0.00001). Margins around the resected tumors were larger (1.62 cm) when flaps were employed compared with margins when defects were closed directly (0.87 cm; P = 0.0005). However, the number of patients with intralesional, marginal, wide, and radical resections was the same regardless of wound management. Major complications occurred in 14% of patients, but none led to death or amputation. The median follow-up was 31 months, and 66% of patients had no evidence of disease at that time. Rates of local recurrence and survival were similar for patients who underwent flap reconstruction compared with patients who underwent direct closure. CONCLUSIONS: Soft tissue flap reconstruction facilitates therapy for patients with soft tissue sarcomas of the upper extremity, so that patients with larger tumors can undergo resection, limiting complications and limb sacrifice.