Construction of millimeter-scale vascularized engineered myocardial tissue using a mixed gel

Engineering myocardium has shown great clinal potential for repairing permanent myocardial injury. However, the lack of perfusing blood vessels and difficulties in preparing a thick-engineered myocardium result in its limited clinical use. We prepared a mixed gel containing fibrin (5 mg/ml) and collagen I (0.2 mg/ml) and verified that human umbilical vein endothelial cells (HUVECs) and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) could form microvascular lumens and myocardial cell clusters by harnessing the low-hardness and hyperelastic characteristics of fibrin. hiPSC-CMs and HUVECs in the mixed gel formed self-organized cell clusters, which were then cultured in different media using a three-phase approach. The successfully constructed vascularized engineered myocardial tissue had a spherical structure and final diameter of 1-2 mm. The tissue exhibited autonomous beats that occurred at a frequency similar to a normal human heart rate. The internal microvascular lumen could be maintained for 6 weeks and showed good results during preliminary surface re-vascularization in vitro and vascular remodeling in vivo. In summary, we propose a simple method for constructing vascularized engineered myocardial tissue, through phased cultivation that does not rely on high-end manufacturing equipment and cutting-edge preparation techniques. The constructed tissue has potential value for clinical use after preliminary evaluation.

Resection of bilateral massive Achilles tendon xanthomata with reconstruction using vascularized iliotibial tract: A case report and literature review

RATIONALE

Cerebrotendinous xanthomatosis is a rare autosomal recessive metabolic disease. Surgical treatment is only indicated when the xanthoma becomes large, painful, and irritable with shoe wear. Reconstruction of the large defect following resection challenging, especially with resection of the entire Achilles tendon.

PATIENT CONCERNS

We report a case of bilateral Achilles tendon defects of 16 cm following resection of bilateral Achilles tendon xanthomata, with reconstruction using vascularized iliotibial tract. The patient had a good functional outcome with well-preserved strength and cosmesis.

OUTCOMES

Reconstruction of a total Achilles tendon defect using Vascularized iliotibial tract is safe and effective.

The Role of Macrophage Phenotype in the Vascularization of Prevascularized Human Bone Marrow Mesenchymal Stem Cell Sheets

With the development of tissue engineering and regenerative medicine, prevascularized bone marrow mesenchymal stem cell (BMSC) sheets have been regarded as a promising method for tissue regeneration. Furthermore, the inflammatory response is one of the main regulators of vascularization and the restoration of engineered tissue function; among them, macrophages and cytokines produced by them are considered to be the decisive factors of the downstream outcomes. This study investigated the effect of macrophages on the formation of microvascular-like structures of human umbilical vein endothelial cells (HUVECs) in BMSC sheets. First, a human monocytic leukemia cell line (THP-1 cells) was differentiated into derived macrophages (M0) with phorbol 12-myristate 13-acetate and further activated into proinflammatory macrophages (M1 macrophages) with interferon-γ and lipopolysaccharide or anti-inflammatory macrophages (M2 macrophages) with interleukin-4. Then, HUVECs and prevascularized sheets were treated with conditioned media (CM) from different macrophages, and the impact of macrophage phenotypes on vascularized network formation in prevascularized cell sheets was examined by hematoxylin and eosin staining, CD31 immunofluorescence staining and enzyme-linked immunosorbent assay. Our study showed that macrophages may guide the arrangement of endothelial cells through a paracrine pathway. Cell sheets that were cultured in the CM from M2 macrophages were thinner than those cultured in other media. At various time points, the levels of tumor necrosis factor alpha and vascular endothelial growth factor in prevascularized sheets cultured with CM(M1) was higher than that in sheets cultured with other media; however, the levels of platelet-derived growth factor in prevascularized sheets cultured with CM(M2) was higher than that in sheets cultured with other media. These findings suggest that the paracrine effect of macrophages can influence the formation of microvascular networks in prevascularized sheets by regulating the arrangement of cells, the thickness of the cell sheet and the secretion of cytokines related to angiogenesis. Macrophages with different phenotypes have unique effects on prevascularized sheets.

3D bioprinting of an implantable xeno-free vascularized human skin graft

Bioengineered tissues or organs produced using matrix proteins or components derived from xenogeneic sources pose risks of allergic responses, immune rejection, or even autoimmunity. Here, we report successful xeno-free isolation, expansion, and cryopreservation of human endothelial cells (EC), fibroblasts (FBs), pericytes (PCs), and keratinocytes (KCs). We further demonstrate the bioprinting of a human skin substitute with a dermal layer containing xeno-free cultured human EC, FBs, and PCs in a xeno-free bioink containing human collagen type I and fibronectin layered in a biocompatible polyglycolic acid mesh and subsequently seeded with xeno-free human KCs to form an epidermal layer. Following implantation of such bilayered skin grafts on the dorsum of immunodeficient mice, KCs form a mature stratified epidermis with rete ridge-like structures. The ECs and PCs form human EC-lined perfused microvessels within 2 weeks after implantation, preventing graft necrosis, and eliciting further perfusion of the graft by angiogenic host microvessels. As proof-of-concept, we generated 12 individual grafts using a single donor of all four cell types. In summary, we describe the fabrication of a bioprinted vascularized bilayered skin substitute under completely xeno-free culture conditions demonstrating feasibility of a xeno-free approach to complex tissue engineering.

Vascularized Bone Grafting for the Treatment of Capitate Avascular Necrosis

Avascular necrosis (AVN) of the capitate bone is a rare condition and it can be related to major trauma or idiopathy. Different treatments are available including soft tissue interposition and intercarpal arthrodesis including lunocapitate, scaphocapitate, four corner, and carpometacarpal fusions. Other surgical options are resection of the proximal pole and revascularization procedures. The main purpose of this article is to present two cases of AVN of the capitate treated with a revascularization procedure using the 4th-5th extensor compartment artery (4th-5th ECA). Two female patients with capitate AVN are reported with an average age of 30.5 years. Both cases were classified as type-I according to Milliez classification. The major complaint in each case was wrist pain that increased during activity. In both cases there was no history of trauma, smoking, diabetes, or hematologic diseases. Both patients had a diminished range of motion, grip, and strength. The definitive diagnosis was made with magnetic resonance imaging. Both patients underwent treatment revascularization of the capitate using a vascularized bone graft based on the 4th-5th ECA. At average follow-up of 12 months, each patient had improved with regards to pain and had increased grip strength. The literature does not describe a specific algorithm treatment for capitate AVN. We recommend revascularization of the capitate using the 4th-5th ECA in type-I Milliez classification in young patients without signs of carpal collapse.

Engineering Microsphere-Loaded Non-mulberry Silk-Based 3D Bioprinted Vascularized Cardiac Patches with Oxygen-Releasing and Immunomodulatory Potential

A hostile myocardial microenvironment post ischemic injury (myocardial infarction) plays a decisive role in determining the fate of tissue-engineered approaches. Therefore, engineering hybrid 3D printed platforms that can modulate the MI microenvironment for improving implant acceptance has surfaced as a critical requirement for reconstructing an infarcted heart. Here, we have employed a non-mulberry silk-based conductive bioink comprising carbon nanotubes (CNTs) to bioprint functional 3D vascularized anisotropic cardiac constructs. Immunofluorescence staining, polymerase chain reaction-based gene expression studies, and electrophysiological studies showed that the inclusion of CNTs in the bioink played a significant role in upregulating matured cardiac biomarkers, sarcomere formation, and beating rate while promoting cardiomyocyte viability. These constructs were then microinjected with calcium peroxide and IL-10-loaded gelatin methacryloyl microspheres. Measurements of oxygen concentration revealed that these microspheres upheld the oxygen availability for maintaining cellular viability for at least 5 days in a hypoxic environment. Also, the ability of microinjected IL-10 microspheres to modulate the macrophages to anti-inflammatory M2 phenotype in vitro was uncovered using immunofluorescent staining and gene expression studies. Furthermore, in vivo subcutaneous implantation of microsphere-injected 3D constructs provided insights toward the extended time frame that was achieved for dealing with the hostile microenvironment for promoting host neovascularization and implant acceptance.

Pedicled vascularized versus non-vascularized bone grafts in the treatment of scaphoid non-union: a meta-analysis of comparative studies

BACKGROUND

Whether pedicled vascularized bone grafts (PVBGs) are beneficial over non-vascularized bone grafts (NVBGs) still remains controversial. The aim of this study was to compare the clinical results of PVBGs and NVBGs for the treatment of scaphoid non-union.

METHODS

We conducted a meta-analysis of the published studies comparing outcomes of these two different surgical techniques for scaphoid non-union. Outcomes of union rate, time to union, functional results and re-operation rate were analysed.

RESULTS

Seven studies including four randomized controlled studies and three retrospective comparative studies with 413 participants were identified fitting inclusion criteria. Meta-analysis showed that (i) union rate in PVBG groups was 1.13 times of NVBG groups (P = 0.002); (ii) the PVBG groups reached bone union significantly earlier by 1.73 weeks (P < 0.01); (iii) there was no significant difference in functional results, including active range of motion, grip strength, Mayo Wrist Score and excellent and good rate (P > 0.05); and (iv) re-operation rate was similar between the two groups (P = 0.65).

CONCLUSIONS

Although the PVBG technique attains higher union rate and earlier union, this radiological advantage does not bring any functional benefits. In addition, PVBGs are of greater technical difficulty and need more operation requirements. Hence, clinicians should be cautious in electing PVBGs for treating scaphoid non-union.

Long-term results of vascularized os pisiform transfer for advanced Kienböck disease after follow-up for at least 15 years: A case series

No surgical procedure perfectly treats advanced Kienböck disease. Although vascularized os pisiform transferring (VOPT) is one of the main therapeutic approaches, reports on long-term follow-up and case series for this technique are scarce.We collected postoperative results in 11 patients with advanced Kienböck disease who underwent VOPT between 1986 and 2001 in our Hospital. Follow-up durations ranged from 15 to 26 years.At the last follow-up, excellent and good results were found in 81.8% according to the Modified Green and O'Brien score. Postoperative imaging revealed significantly reduced pisiform bone; carpal height ratio and Nattrass index were decreased, while the radioscaphoid angle was increscent, compared with preoperative and mid-term follow-up results.The favorable long-term results demonstrated that VOPT is a dependable and durable procedure for the treatment of advanced Kienböck disease, with pain relief and functional improvement despite some radiographic findings such as wrist osteoarthritis occurrence.

Bone Graft Options in Upper-Extremity Surgery

Bone grafting in the upper extremity is an important consideration in patients with injuries or conditions resulting in missing bone stock. A variety of indications can necessitate bone grafting in the upper extremity, including fractures with acute bone loss, nonunions, malunions, bony lesions, and bone loss after osteomyelitis. Selecting the appropriate bone graft option for the specific consideration is important to ensure optimal patient outcomes. Considerations such as donor site morbidity and the amount and characteristics of bone graft needed all weigh in the decision making regarding which type of bone graft to use. This article reviews the options available for bone grafting in the upper extremity.

A new surgical treatment for abdominal wall defects: A vascularized ribs-pleural transfer technique that can be used with or without a thoracic umbilical flap a case report

RATIONALE

Abdominal wall defects are common after tumor resection.

PATIENT CONCERNS

We report an 83-year-old male patient with recurrent tumors in his abdomen, and who had an incision wound that could not be directly closed. Mesh was not suitable because the wound was infected.

DIAGNOSES

Abdominal wall defect result from the resection of recurrent tumor.

INTERVENTIONS

We carried out a vascularized ribs-pleural transfer operation.

OUTCOMES

After the surgery, the patient gained a functional recovery. No evidence of recurrence was noted 1 year after operation, and the patient showed no symptoms of abdominal compression syndrome.

LESSONS

We discuss the clinical diagnosis, treatment, and follow up and argue that the vascularized ribs-pleural transfer technique is a good method to deal with abdominal wall defects.

Scaphoid nonunion: what is the role of the Zaidemberg 1,2 intercompartmental supraretinacular arterial flap?

The reported results for the treatment of scaphoid nonunions with non-vascularized grafts are based on observational studies with a high variability in union rates from 38%-100% and time to union from 6-18 weeks, and there is also a lack of a standard classification. Meta-analyses and systematic reviews have been presented to better support conclusions from large pools of data (604 to 5246 cases), but their interpretation remains limited because of lack of uniformity in the studies analysed. Several authors have presented results from the Zaidemburg flap, with highly variable outcomes despite using the same technique; union rates have ranged from 27%-100% achieved between 6.5-19 weeks. Technical details that may be responsible for the discrepancies are discussed. There is a need for a validated prognostic classification system for scaphoid nonunions that can allow comparisons between outcome studies.

A Tip for the Reconstruction of Larger Maxillary Defects in Complicated Cleft Patients

Residual alveolar cleft deficits can be difficult to treat. This is particularly the case in older and multiply operated patients as well as those with large oronasal defects and extensive scar tissue. In large and recalcitrant defects vascularized free tissue transfer should be considered as a definitive procedure. Vascularized free tissue transfer provides a 95% success rate and provides excellent bone for placement of osseointegrated implants for dental rehabilitation (Schwabegger et al., 2004). We feel that the scapula tip has a number of important advantages. These include reduced morbidity from the donor site, good bone quality and contour for implant placement, and a longer pedicle length.

Success of scaphoid nonunion surgery is independent of proximal pole vascularity

We followed 35 consecutive patients with scaphoid nonunions in a prospective longitudinal registry. All nonunions were treated with curettage, non-vascularized autogenous grafting and headless screw fixation. Preoperative magnetic resonance imaging, intraoperative bleeding points and histopathological analysis of cancellous bone in the proximal pole were recorded as measures of viability. Healing was categorized as ≥50% bony bridging on computed tomographic images in the plane of the scaphoid. Nine of 23 proximal poles demonstrated ischaemia on magnetic resonance imaging but none were interpreted as infarcted. Twenty-eight of 33 were found to have impaired vascularity as assessed by intraoperative bleeding. Fourteen of 32 demonstrated ≥50% trabecular necrosis and four of 33 demonstrated ≥50% tissue necrosis on histopathological analysis. Thirty of 33 demonstrated focal or robust remodelling activity. Despite pathological evidence of impaired vascularity in over half of the patients, 33 of the 35 scaphoids had healed by 12 weeks. We conclude that proximal pole infarction is decidedly rare and that vascularized bone grafting is seldom required.

LEVEL OF EVIDENCE

IV.

Retrospective Analysis of Giant Cell Tumor Lower End Radius Treated with En bloc Excision and Translocation of Ulna

BACKGROUND

Distal end of radius is third most common site for GCT of long bones and 1% of these metastasize mostly to lungs. Reconstruction methods commonly used are fibula (vascularized and nonvascularized), centralization of ulna, translocation of ulna, and endoprosthetic replacement. We report the outcome of series of twenty cases where we did en bloc excision of tumor with translocation of ulna.

MATERIALS AND METHODS

Twenty cases of giant cell tumor (GCT) of lower end of radius were included in this retrospective study. The mean age of patients was 33.15 years (range 21-55 years). We had 14 of Campanacci Grade III and 6 of Grade II. Preoperative radiographs and magnetic resonance imaging of the involved wrist and forearm were done.

RESULTS

Of all twenty patients, 14 were males and 6 were females. Mean followup duration was 3.9 years (range 1.5-17 years). Mean grip strength of involved side as a percentage of normal side was 71% (range 42%-86%) and the actual mean value for operated side was 29 kg as compared to 40 kg for normal side. The average range of forearm movement was supination 80.25° (60°-90°) and pronation 77.5° (70°-90°). No patient was dissatisfied as far as cosmesis was concerned.

DISCUSSION

In our opinion considering the propensity to recur with more aggressiveness after recurrence, en bloc excision with translocation of ulna has become a standard treatment option for GCT of lower end of radius, with advantages of better functional outcomes, retained vascularity, and elimination of risk of donor site morbidity.

Comparative meta-analysis on the various vascularized bone flaps used for the treatment of scaphoid nonunion

We did a meta-analysis of the literature in order to clarify which of the vascularized bone flaps (VBF) used for scaphoid non-union treatment has the best outcome with regard to various parameters. We analyzed 54 articles that present nine different types of VBF. The analysis concerned demographical patient information, radiographic parameters, fracture classification, including the presence or non-presence of avascular necrosis of the scaphoid proximal pole (PP AVN), parameters that have to do with the surgery itself and the postoperative protocol, the healing of the nonunion and functional scores. The meta-analysis showed best healing potential for the femoral graft despite the complexity of the operation. On the other hand, the most commonly used 1,2-ICSRA flap makes the procedure more reproducible but showed worse results. The femoral flap was also among the most successful flaps when used for patients with PP AVN. The consolidation rate, in general, was not affected by the time elapsed between the fracture and the operation but by smoking and the presence of PP AVN. The meta-analysis could not reach many significant statistical conclusions because of either the small number of patients in some flap groups or the heterogeneity and lack of documentation in most of the articles. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1076-1085, 2017.

Vascularized versus non-vascularized bone grafts in the treatment of scaphoid non-union

INTRODUCTION

Conventional non-vascularized bone grafts as well as vascularized bone grafts are used to treat scaphoid non-union (SN). Due to limited available studies, the field of application using both grafts for SN still remains controversial. The aim of this study was to evaluate a treatment algorithm for the use of both vascularized versus non-vascularized bone grafts based on clinical outcomes and quality of life (QoL) to improve the level of evidence.

MATERIALS AND METHODS

Based on a retrospective cohort study, including 28 patients with vascularized and 45 patients with conventional bone grafts, functional parameters, radiological outcome, Mayo-wrist-score, and QoL by SF-36 were applied to statistically compare the outcome of these two techniques.

RESULTS

Time between last procedure or trauma and study group scaphoid reconstruction was almost double in the vascularized bone grafting group. Comparable union rates were achieved with vascularized as well as non-vascularized bone grafts. Significant differences were observed between both groups for grip strength and radial-ulnar active range of motion. Further functional outcomes, radiological outcomes as well as QoL were found similar for both techniques in patients with surgical union.

DISCUSSION AND CONCLUSIONS

In order to achieve comparable and appropriate treatment results, vascularized bone grafts are recommended for patients with delayed treatment, impaired scaphoid vascularity, and revision surgery. Even in preselected, complex cases, the results are comparable to conventional grafts, which are the basis for further patient education and approve the powerful role of surgical angiogenesis of vascularized bone grafts.

Reconstruction of scaphoid nonunion fractures of the proximal one third with a vascularized bone graft from the distal radius

OBJECTIVE

The treatment of proximal located scaphoid nonunion is a well-known and common problem. For these patients, we used a vascular pedicled bone graft of the distal radius.

METHODS

In the last 7 years, 75 patients were treated with the vascular pedicled bone graft. Retrospectively, patients' data, healing rates, and factors influencing scaphoid healing were analyzed.

RESULTS

The overall healing rate in cases with proximal located nonunions (n = 54) was approximately 70%. Out of these 54 patients, 47 patients showed avascular proximal fragments. Multivariate analysis showed no significant impact for the factors age, smoking, duration of disease, or previous operation.

CONCLUSIONS

In our negative selected patient group, we were able to achieve good results with the usage of a pedicled vascularized bone graft of the distal radius. Our results indicate a favorable outcome for the use of a pedicled vascularized distal radius bone graft in both scaphoid nonunion fractures of the proximal third, with or without an avascular proximal pole.

Minimum 6-year follow-up after ulnar nerve decompression and submuscular transposition for primary entrapment

PURPOSE

To retrospectively evaluate patients with 6-year minimum follow-up after submuscular transposition of the ulnar nerve for primary entrapment.

METHODS

From 1992 to 2005, 142 patients were treated surgically for ulnar neuropathy at the elbow by 2 senior surgeons using a technique that preserved nerve vascularity. A total of 99 cases were eligible, and 82 elbows in 76 patients, average age 48 years, were followed for at least 6 years (average, 8.3 y). Thirty-two (42%) were male, and the dominant limb was involved in 49 (64%). The average duration of symptoms before surgery was 25 months. Clinical records were reviewed, and sensory (S0-2) and motor (M0-5) testing was performed. Dellon scores were determined, and visual analog scale and modified questionnaires from Novak et al and Kleinman and Bishop were completed. Preoperatively, 48 elbows were Dellon grade III, 33 were grade II, and one was grade I.

RESULTS

There were clinically and statistically significant improvements in patient and surgeon-reported data regardless of the preoperative disease severity. Visual analog scale questionnaires, sensory scale, and motor strength all improved, with at least antigravity strength in all subjects. Dellon scores also improved, and 38 elbows had normalized to Dellon 0. Of the 33 preoperative elbows that were grade III, 15 improved to grade II, 13 to grade I, and 5 normalized. Of the 48 preoperative elbows that were grade II, 16 improved to grade I and 32 normalized. Preoperative Dellon III elbows had more residual symptoms than grade II elbows. A total of 73 elbows (89%) had a good or excellent outcome. There were no reoperations or infections.

CONCLUSIONS

Submuscular transposition is a safe and durable option for primary ulnar neuropathy at the elbow. Overall, good or excellent results were achieved in 89% of patients with a low complication rate.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Treatment of avascular proximal pole scaphoid nonunions with vascularized distal radius bone grafting

PURPOSE

To investigate the outcomes of vascularized distal radius pedicled bone grafting secured with K-wires for scaphoid nonunions with small avascular proximal fragments.

METHODS

We included patients with scaphoid nonunions and small, avascular proximal fragments that were too small for screw fixation. The mean size of the proximal pole fragments was 21% (range, 9% to 28%) of the entire scaphoid, based on quantitative radiographic measurement. All patients had distal radius bone grafting based on the 1,2-intercompartmental supraretinacular artery pedicle and fixation with K-wires. There were 21 wrists in 18 men and 2 women with the mean age of 34 years (range, 22 to 57 y). The mean duration of postoperative follow-up was 40 months (range, 12 to 103 mo). Radiographic union and clinical outcomes, including the ranges of wrist motion, grip strength, and the modified Mayo wrist score, were evaluated.

RESULTS

Union was achieved in 18 of 21 wrists (86%) at a mean time of 14 weeks after surgery (range, 8 to 28 wk). Nonunions with proximal fragments less than 20% of the total scaphoid healed in 6 of 8 wrists. In a subset of these 8 wrists in which the proximal fragment was less than 15%, healing occurred in 2 of 4. The modified Mayo wrist score significantly improved from 46 to 78 points, and final wrist functions were rated as excellent in 5, good in 5, fair in 10, and poor in 1. Ranges of motion and grip strengths did not show significant changes after surgery.

CONCLUSIONS

Vascularized distal radius bone grafting and K-wire fixation can heal scaphoid nonunions with small avascular proximal fragments, although motion and grip strength remain unchanged. Healing may be related to the size of the proximal pole fragment.

Bone grafts in craniofacial surgery

Reconstruction of cranial and maxillofacial defects is a challenging task. The standard reconstruction method has been bone grafting. In this review, we shall describe the biological principles of bone graft healing, as pertinent to craniofacial reconstruction. Different types and sources of bone grafts will be discussed, as well as new methods of bone defect reconstruction.

Vascularized options for reconstruction of the mandibular condyle

The temporomandibular joint is elegant in its design, which may make it difficult if not impossible to comprehensively reconstruct. Although a broad range of nonvascularized options exists for reconstruction of degenerative conditions of the temporomandibular joint, vascularized reconstructions such as the fibula or the second metatarsal phalangeal joint are more appropriate for defects resulting from oncologic resection or in patients with compromised soft tissue. An anatomically based classification system for these defects is presented.