A scoping review of graphene-based biomaterials for in vivo bone tissue engineering

The growing demand for more efficient materials for medical applications brought together two previously distinct fields: medicine and engineering. Regenerative medicine has evolved with the engineering contributions to improve materials and devices for medical use. In this regard, graphene is one of the most promising materials for bone tissue engineering and its potential for bone repair has been studied by several research groups. The aim of this study is to conduct a scoping review including articles published in the last 12 years (from 2010 to 2022) that have used graphene and its derivatives (graphene oxide and reduced graphene) in preclinical studies for bone tissue regeneration, searching in PubMed/MEDLINE, Embase, Web of Science, Cochrane Central, and clinicaltrials.gov (to confirm no study has started with clinical trial). Boolean searches were performed using the defined key words "bone" and "graphene", and manuscript abstracts were uploaded to Rayyan, a web-tool for systematic and scoping reviews. This scoping review was conducted based on Joanna Briggs Institute Manual for Scoping Reviews and the report follows the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses - Extension for Scoping Reviews (PRISMA-ScR) statement. After the search protocol and application of the inclusion criteria, 77 studies were selected and evaluated by five blinded researchers. Most of the selected studies used composite materials associated with graphene and its derivatives to natural and synthetic polymers, bioglass, and others. Although a variety of graphene materials were analyzed in these studies, they all concluded that graphene, its derivatives, and its composites improve bone repair processes by increasing osteoconductivity, osteoinductivity, new bone formation, and angiogenesis. Thus, this systematic review opens up new opportunities for the development of novel strategies for bone tissue engineering with graphene.

In vitro assessment of Neuronal PAS domain 2 mitigating compounds for scarless wound healing

Background

The core circadian gene Neuronal PAS domain 2 (NPAS2) is expressed in dermal fibroblasts and has been shown to play a critical role in regulating collagen synthesis during wound healing. We have performed high throughput drug screening to identify genes responsible for downregulation of Npas2 while maintaining cell viability. From this, five FDA-approved hit compounds were shown to suppress Npas2 expression in fibroblasts. In this study, we hypothesize that the therapeutic suppression of Npas2 by hit compounds will have two effects: (1) attenuated excessive collagen deposition and (2) accelerated dermal wound healing without hypertrophic scarring.

Materials and methods

To test the effects of each hit compound (named Dwn1, 2, 3, 4, and 5), primary adult human dermal fibroblasts (HDFa) were treated with either 0, 0.1, 1, or 10 μM of a single hit compound. HDFa behaviors were assessed by picrosirius red staining and quantitative RT-PCR for in vitro collagen synthesis, cell viability assay, in vitro fibroblast-to-myofibroblast differentiation test, and cell migration assays.

Results

Dwn1 and Dwn2 were found to significantly affect collagen synthesis and cell migration without any cytotoxicity. Dwn3, Dwn4, and Dwn5 did not affect collagen synthesis and were thereby eliminated from further consideration for their role in mitigation of gene expression or myofibroblast differentiation. Dwn1 also attenuated myofibroblast differentiation on HDFa.

Conclusion

Dwn1 and Dwn2 may serve as possible therapeutic agents for future studies related to skin wound healing.

Prospective analysis of a surgical algorithm to achieve ventilator weaning in cervical tetraplegia

Objectives: Chronic ventilator dependency in cervical tetraplegia is associated with substantial morbidity. When non-invasive weaning methods have failed the primary surgical treatment is diaphragm pacing. Phrenic nerve integrity and diaphragm motor units are requirements for effective pacing but may need to be restored for successful weaning. A surgical algorithm that includes: 1. Diaphragm pacing, 2. Phrenic nerve reconstruction, and 3. Diaphragm muscle replacement, may provide the capability of reducing or reversing ventilator dependency in virtually all cervical tetraplegics.Design: Prospective case series.Setting: A university-based hospital from 2015 to 2019.Participants: Ten patients with ventilator-dependent cervical tetraplegia.Interventions: I. Pacemaker alone, II. Pacemaker + phrenic nerve reconstruction, or III. Pacemaker + diaphragm muscle replacement.Outcome measures: Time from surgery to observed reduction in ventilator requirements (↓VR), ventilatory needs as of most recent follow-up [no change (NC), partial weaning (PW, 1-12 h/day), or complete weaning (CW, >12 h/day)], and complications.Results: Both patients in Group I achieved CW at 6-month follow-up. Two patients in Group II achieved CW, and in another two patients PW was achieved, at 1.5-2-year follow-up. The remaining two patients are NC at 6 and 8-month follow-up, respectively. In group III, both patients achieved PW at 2-year follow-up. Complications included mucous plugging (n = 1) and pacemaker malfunction requiring revision (n = 3).Conclusion: Although more investigation is necessary, phrenic nerve reconstruction or diaphragm muscle replacement performed (when indicated) with pacemaker implantation may allow virtually all ventilator-dependent cervical tetraplegics to partially or completely wean.

Therapeutic downregulation of neuronal PAS domain 2 (Npas2) promotes surgical skin wound healing

Attempts to minimize scarring remain among the most difficult challenges facing surgeons, despite the use of optimal wound closure techniques. Previously, we reported improved healing of dermal excisional wounds in circadian clock neuronal PAS domain 2 (Npas2)-null mice. In this study, we performed high-throughput drug screening to identify a compound that downregulates Npas2 activity. The hit compound (Dwn1) suppressed circadian Npas2 expression, increased murine dermal fibroblast cell migration, and decreased collagen synthesis in vitro. Based on the in vitro results, Dwn1 was topically applied to iatrogenic full-thickness dorsal cutaneous wounds in a murine model. The Dwn1-treated dermal wounds healed faster with favorable mechanical strength and developed less granulation tissue than the controls. The expression of type I collagen, Tgfβ1, and α-smooth muscle actin was significantly decreased in Dwn1-treated wounds, suggesting that hypertrophic scarring and myofibroblast differentiation are attenuated by Dwn1 treatment. NPAS2 may represent an important target for therapeutic approaches to optimal surgical wound management.

Phrenic Nerve Reconstruction for Effective Surgical Treatment of Diaphragmatic Paralysis

ABSTRACT

Diaphragmatic paralysis due to phrenic nerve injury may cause orthopnea, exertional dyspnea, and sleep-disordered breathing. Phrenic nerve reconstruction may relieve symptoms and improve respiratory function. A retrospective review of 400 consecutive patients undergoing phrenic nerve reconstruction for diaphragmatic paralysis at 2 tertiary treatment centers was performed between 2007 and 2019. Symptomatic patients were identified, and the diagnosis was confirmed on radiographic evaluations. Assessment parameters included pulmonary spirometry (forced expiratory volume in 1 second and FVC), maximal inspiratory pressure, compound muscle action potentials, diaphragm thickness, chest fluoroscopy, and Short Form 36 Health Survey Questionnaire (SF-36) survey. There were 81 females and 319 males with an average age of 54 years (range, 19-79 years). The mean duration from diagnosis to surgery was 29 months (range, 1-320 months). The most common etiologies were acute or chronic injury (29%), interscalene nerve block (17%), and cardiothoracic surgery (15%). The mean improvements in forced expiratory volume in 1 second and FVC at 1 year were 10% (P < 0.01) and 8% (P < 0.05), respectively. At 2-year follow-up, the corresponding values were 22% (P < 0.05) and 18% (P < 0.05), respectively. Improvement on chest fluoroscopy was demonstrated in 63% and 71% of patients at 1 and 2-year follow-up, respectively. There was a 20% (P < 0.01) improvement in maximal inspiratory pressure, and compound muscle action potentials increased by 82% (P < 0.001). Diaphragm thickness demonstrated a 27% (P < 0.01) increase, and SF-36 revealed a 59% (P < 0.001) improvement in physical functioning. Symptomatic diaphragmatic paralysis should be considered for surgical treatment. Phrenic nerve reconstruction can achieve symptomatic relief and improve respiratory function. Increasing spirometry and improvements on Sniff from 1 to 2 years support incremental recovery with longer follow-up.

Treatment for bilateral diaphragmatic dysfunction using phrenic nerve reconstruction and diaphragm pacemakers

OBJECTIVES

Bilateral diaphragmatic dysfunction results in severe dyspnoea, usually requiring oxygen therapy and nocturnal ventilatory support. Although treatment options are limited, phrenic nerve reconstruction (PR) offers the opportunity to restore functional activity. This study aims to evaluate combination treatment with PR and placement of a diaphragm pacemaker (DP) compared to DP placement alone in patients with bilateral diaphragmatic dysfunction.

METHODS

Patients with bilateral diaphragmatic dysfunction were prospectively enrolled in the following treatment algorithm: Unilateral PR was performed on the more severely impacted side with bilateral DP implantation. Motor amplitudes, ultrasound measurements of diaphragm thickness, maximal inspiratory pressure, forced expiratory volume, forced vital capacity and subjective patient-reported outcomes were obtained for retrospective analysis following completion of the prospective database.

RESULTS

Fourteen male patients with bilateral diaphragmatic dysfunction confirmed on chest fluoroscopy and electrodiagnostic testing were included. All 14 patients required nocturnal ventilator support, and 8/14 (57.1%) were oxygen-dependent. All patients reported subjective improvement, and all 8 oxygen-dependent patients were able to discontinue oxygen therapy following treatment. Improvements in maximal inspiratory pressure, forced vital capacity and forced expiratory volume were 68%, 47% and 53%, respectively. There was an average improvement of 180% in motor amplitude and a 50% increase in muscle thickness. Comparison of motor amplitude changes revealed significantly greater functional recovery on the PR + DP side.

CONCLUSIONS

PR and simultaneous implantation of a DP may restore functional activity and alleviate symptoms in patients with bilateral diaphragmatic dysfunction. PR plus diaphragm pacing appear to result in greater functional muscle recovery than pacing alone.

Human levator veli palatini muscle: a novel source of mesenchymal stromal cells for use in the rehabilitation of patients with congenital craniofacial malformations

Background

Bone reconstruction in congenital craniofacial differences, which affect about 2–3% of newborns, has long been the focus of intensive research in the field of bone tissue engineering. The possibility of using mesenchymal stromal cells in regenerative medicine protocols has opened a new field of investigation aimed at finding optimal sources of multipotent cells that can be isolated via non-invasive procedures. In this study, we analyzed whether levator veli palatini muscle fragments, which can be readily obtained in non-invasive manner during palatoplasty in cleft palate patients, represent a novel source of MSCs with osteogenic potential.

Methods

We obtained levator veli palatini muscle fragments (3–5 mm³), during surgical repair of cleft palate in 5 unrelated patients. Mesenchymal stromal cells were isolated from the muscle using a pre-plating technique and other standard practices. The multipotent nature of the isolated stromal cells was demonstrated via flow cytometry analysis and by induction along osteogenic, adipogenic, and chondrogenic differentiation pathways. To demonstrate the osteogenic potential of these cells in vivo, they were used to reconstruct a critical-sized full-thickness calvarial defect model in immunocompetent rats.

Results

Flow cytometry analysis showed that the isolated stromal cells were positive for mesenchymal stem cell antigens (CD29, CD44, CD73, CD90, and CD105) and negative for hematopoietic (CD34 and CD45) or endothelial cell markers (CD31). The cells successfully underwent osteogenic, chondrogenic, and adipogenic cell differentiation under appropriate cell culture conditions. Calvarial defects treated with CellCeram™ scaffolds seeded with the isolated levator veli palatini muscle cells showed greater bone healing compared to defects treated with acellular scaffolds.

Conclusion

Cells derived from levator veli palatini muscle have phenotypic characteristics similar to other mesenchymal stromal cells, both in vitro and in vivo. Our findings suggest that these cells may have clinical relevance in the surgical rehabilitation of patients with cleft palate and other craniofacial anomalies characterized by significant bone deficit.

Supplementary information

The online version contains supplementary material available at 10.1186/s13287-020-02017-7.

Non-invasive terahertz imaging of tissue water content for flap viability assessment

Accurate and early prediction of tissue viability is the most significant determinant of tissue flap survival in reconstructive surgery. Perturbation in tissue water content (TWC) is a generic component of the tissue response to such surgeries, and, therefore, may be an important diagnostic target for assessing the extent of flap viability in vivo. We have previously shown that reflective terahertz (THz) imaging, a non-ionizing technique, can generate spatially resolved maps of TWC in superficial soft tissues, such as cornea and wounds, on the order of minutes. Herein, we report the first in vivo pilot study to investigate the utility of reflective THz TWC imaging for early assessment of skin flap viability. We obtained longitudinal visible and reflective THz imagery comparing 3 bipedicled flaps (i.e. survival model) and 3 fully excised flaps (i.e. failure model) in the dorsal skin of rats over a postoperative period of 7 days. While visual differences between both models manifested 48 hr after surgery, statistically significant (p < 0.05, independent t-test) local differences in TWC contrast were evident in THz flap image sets as early as 24 hr. Excised flaps, histologically confirmed as necrotic, demonstrated a significant, yet localized, reduction in TWC in the flap region compared to non-traumatized skin. In contrast, bipedicled flaps, histologically verified as viable, displayed mostly uniform, unperturbed TWC across the flap tissue. These results indicate the practical potential of THz TWC sensing to accurately predict flap failure 24 hours earlier than clinical examination.

Long-Term Follow-Up after Phrenic Nerve Reconstruction for Diaphragmatic Paralysis: A Review of 180 Patients

Background Phrenic nerve reconstruction has been evaluated as a method of restoring functional activity and may be an effective alternative to diaphragm plication. Longer follow-up and a larger cohort for analysis are necessary to confirm the efficacy of this procedure for diaphragmatic paralysis. Methods A total of 180 patients treated with phrenic nerve reconstruction for chronic diaphragmatic paralysis were followed for a median 2.7 years. Assessment parameters included: 36-Item Short Form Health Survey (SF-36) physical functioning survey, spirometry, chest fluoroscopy, electrodiagnostic evaluation, a five-item questionnaire to assess specific functional issues, and overall patient-reported outcome. Results Overall, 134 males and 46 females with an average age of 56 years (range: 10-79 years) were treated. Mean baseline percent predicted values for forced expiratory volume in 1 second, forced vital capacity, vital capacity, and total lung capacity, were 61, 63, 67, and 75%, respectively. The corresponding percent improvements in percent predicted values were: 11, 6, 9, and 13% (p ≤ 0.01; ≤ 0.01; ≤ 0.05; ≤ 0.01). Mean preoperative SF-36 physical functioning survey scores were 39%, and an improvement to 65% was demonstrated following surgery (p ≤ 0.0001). Nerve conduction latency, improved by an average 23% (p ≤ 0.005), and there was a corresponding 125% increase in diaphragm motor amplitude (p ≤ 0.0001). A total of 89% of patients reported an overall improvement in breathing function. Conclusion Long-term assessment of phrenic nerve reconstruction for diaphragmatic paralysis indicates functional correction and symptomatic relief.

Oxy133, a novel osteogenic agent, promotes bone regeneration in an intramembranous bone-healing model

Current reconstructive techniques for complex craniofacial osseous defects are challenging and are associated with significant morbidity. Oxysterols are naturally occurring cholesterol oxidation products with osteogenic potential. In this study, we investigated the effects of a novel semi-synthetic oxysterol, Oxy133, on in vitro osteogenesis and an in vivo intramembranous bone-healing model. Rabbit bone marrow stromal cells (BMSCs) were treated with either Oxy133 or BMP-2. Alkaline phosphatase (ALP) activity, expression of osteogenic gene markers and in vitro mineralization were all examined. Next, collagen sponges carrying either Oxy133 or BMP-2 were used to reconstruct critical-sized cranial defects in mature rabbits and bone regeneration was assessed. To determine the mechanism of action of Oxy133 both in vitro and in vivo, rabbit BMSCs cultures and collagen sponge/Oxy133 implants were treated with the Hedgehog signalling pathway inhibitor, cyclopamine, and similar outcomes were measured. ALP activity in rabbit BMSCs treated with 1 μm Oxy133 was induced and was significantly higher than in control cells. These results were mitigated in cultures treated with cyclopamine. Expression of osteogenic gene markers and mineralization in BMSCs treated with 1 μm Oxy133 was significantly higher than in control groups. Complete bone regeneration was noted in vivo when cranial defects were treated with Oxy133; healing was incomplete, however, when cyclopamine was added. Collectively, these results demonstrate that Oxy133 has the ability to induce osteogenic differentiation in vitro in rabbit BMSCs and to promote robust bone regeneration in vivo in an animal model of intramembranous bone healing. Copyright © 2015 John Wiley & Sons, Ltd.

The use of negative pressure wound therapy in severe open lower extremity fractures: identifying the association between length of therapy and surgical outcomes

BACKGROUND

Negative pressure wound therapy (NPWT) is a widely accepted method of temporary coverage for complex lower extremity wounds before definitive reconstruction. However, the precise role of NPWT in the perioperative management of patients with complicated lower extremity injuries remains unclear. In this study, we examine the effect of NPWT on flap complications and overall outcomes based on timing of soft-tissue reconstruction relative to initial injury and implementation of NPWT.

METHODS

We retrospectively reviewed the medical records of 32 consecutive patients presenting to a single institution receiving lower extremity reconstruction after Gustilo class IIIB or IIIC open tibial fractures over a 5-y period. Length of hospitalization, number of surgical procedures, flap failure, infection, and nonunion were parameters of interest in this study.

RESULTS

The incidence of complications in patients treated with NPWT was lower compared with patients who underwent wet-to-dry dressing changes, regardless of when surgery was performed. The highest rate of complications was observed in patients operated on >6 wk after injury and who received wet-to-dry dressing changes wound care. By comparison, those who underwent surgery within 1 wk of injury and who were bridged with NPWT had the lowest rate of complications.

CONCLUSIONS

The use of NPWT therapy in the perioperative management of patients with open lower extremity fractures reduces complication rates associated with limb salvage surgery. Our results suggest that NPWT can be used as a temporizing measure to optimize patients before flap surgery, effectively lengthening the window of opportunity for definitive reconstruction.

Diaphragmatic reinnervation in ventilator-dependent patients with cervical spinal cord injury and concomitant phrenic nerve lesions using simultaneous nerve transfers and implantable neurostimulators

BACKGROUND

Patients who are ventilator dependent as a result of combined cervical spinal cord injury and phrenic nerve lesions are generally considered to be unsuitable candidates for diaphragmatic pacing due to loss of phrenic nerve integrity and denervation of the diaphragm. There is limited data regarding efficacy of simultaneous nerve transfers and diaphragmatic pacemakers in the treatment of this patient population.

METHODS

A retrospective review was conducted of 14 consecutive patients with combined lesions of the cervical spinal cord and phrenic nerves, and with complete ventilator dependence, who were treated with simultaneous microsurgical nerve transfer and implantation of diaphragmatic pacemakers. Parameters of interest included time to recovery of diaphragm electromyographic activity, average time pacing without the ventilator, and percent reduction in ventilator dependence.

RESULTS

Recovery of diaphragm electromyographic activity was demonstrated in 13 of 14 (93%) patients. Eight of these 13 (62%) patients achieved sustainable periods (> 1 h/d) of ventilator weaning (mean = 10 h/d [n = 8]). Two patients recovered voluntary control of diaphragmatic activity and regained the capacity for spontaneous respiration. The one patient who did not exhibit diaphragmatic reinnervation remains within 12 months of initial treatment. Surgical intervention resulted in a 25% reduction (p < 0.05) in ventilator dependency.

CONCLUSION

We have demonstrated that simultaneous nerve transfers and pacemaker implantation can result in reinnervation of the diaphragm and lead to successful ventilator weaning. Our favorable outcomes support consideration of this surgical method for appropriate patients who would otherwise have no alternative therapy to achieve sustained periods of ventilator independence.

Ophthalmic manifestations of cherubism

Cherubism is a rare craniofacial disorder characterized by progressive replacement of mandibular and maxillary bone with multicystic fibro-osseous tissue, potentially resulting in significant deformity and morbidity. The severity of the disorder is variable; more advanced disease may affect the orbit and impact vision. We detail the ophthalmological findings in 2 patients, 7 and 8 years of age, with cherubism.

A bioengineered peripheral nerve construct using aligned peptide amphiphile nanofibers

Peripheral nerve injuries can result in lifelong disability. Primary coaptation is the treatment of choice when the gap between transected nerve ends is short. Long nerve gaps seen in more complex injuries often require autologous nerve grafts or nerve conduits implemented into the repair. Nerve grafts, however, cause morbidity and functional loss at donor sites, which are limited in number. Nerve conduits, in turn, lack an internal scaffold to support and guide axonal regeneration, resulting in decreased efficacy over longer nerve gap lengths. By comparison, peptide amphiphiles (PAs) are molecules that can self-assemble into nanofibers, which can be aligned to mimic the native architecture of peripheral nerve. As such, they represent a potential substrate for use in a bioengineered nerve graft substitute. To examine this, we cultured Schwann cells with bioactive PAs (RGDS-PA, IKVAV-PA) to determine their ability to attach to and proliferate within the biomaterial. Next, we devised a PA construct for use in a peripheral nerve critical sized defect model. Rat sciatic nerve defects were created and reconstructed with autologous nerve, PLGA conduits filled with various forms of aligned PAs, or left unrepaired. Motor and sensory recovery were determined and compared among groups. Our results demonstrate that Schwann cells are able to adhere to and proliferate in aligned PA gels, with greater efficacy in bioactive PAs compared to the backbone-PA alone. In vivo testing revealed recovery of motor and sensory function in animals treated with conduit/PA constructs comparable to animals treated with autologous nerve grafts. Functional recovery in conduit/PA and autologous graft groups was significantly faster than in animals treated with empty PLGA conduits. Histological examinations also demonstrated increased axonal and Schwann cell regeneration within the reconstructed nerve gap in animals treated with conduit/PA constructs. These results indicate that PA nanofibers may represent a promising biomaterial for use in bioengineered peripheral nerve repair.

Stimulation of bone regeneration following the controlled release of water-insoluble oxysterol from biodegradable hydrogel

Recently bone graft substitutes using bone morphogenetic proteins (BMPs) have been heralded as potential alternatives to traditional bone reconstruction procedures. BMP-based products, however, are associated with significant and potentially life-threatening side effects when used in the head and neck region and furthermore, are exorbitantly priced. Oxysterols, products of cholesterol oxidation, represent a class of molecules that are favorable alternatives or adjuncts to BMP therapy due to their low side effect profile and cost. In order to establish the optimal clinical utility of oxysterol, an optimal scaffold must be developed, one that allows the release of oxysterol in a sustained and efficient manner. In this study, we prepare a clinically applicable bone graft substitute engineered for the optimal release of oxysterol. We first solubilized oxysterol in water by making use of polymeric micelles using l-lactic acid oligomer (LAo) grafted gelatin. Then, the water-solubilized oxysterol was incorporated into a biodegradable hydrogel that was enzymatically degraded intracorporeally. In this manner, oxysterol could be released from the hydrogel in a degradation-driven manner. The water-solubilized oxysterol incorporated biodegradable hydrogel was implanted into rat calvarial defects and induced successful bone regeneration. The innovative significance of this study lies in the development of a bone graft substitute that couples the osteogenic activity of oxysterol with a scaffold designed for optimized oxysterol release kinetics, all of which lead to better repair of bone defects.

Functional restoration of diaphragmatic paralysis: an evaluation of phrenic nerve reconstruction

BACKGROUND

Unilateral diaphragmatic paralysis causes respiratory deficits and can occur after iatrogenic or traumatic phrenic nerve injury in the neck or chest. Patients are evaluated using spirometry and imaging studies; however, phrenic nerve conduction studies and electromyography are not widely available or considered; thus, the degree of dysfunction is often unknown. Treatment has been limited to diaphragmatic plication. Phrenic nerve operations to restore diaphragmatic function may broaden therapeutic options.

METHODS

An interventional study of 92 patients with symptomatic diaphragmatic paralysis assigned 68 (based on their clinical condition) to phrenic nerve surgical intervention (PS), 24 to nonsurgical (NS) care, and evaluated a third group of 68 patients (derived from literature review) treated with diaphragmatic plication (DP). Variables for assessment included spirometry, the Short-Form 36-Item survey, electrodiagnostics, and complications.

RESULTS

In the PS group, there was an average 13% improvement in forced expiratory volume in 1 second (p < 0.0001) and 14% improvement in forced vital capacity (p < 0.0001), and there was corresponding 17% (p < 0.0001) and 16% (p < 0.0001) improvement in the DP cohort. In the PS and DP groups, the average postoperative values were 71% for forced expiratory volume in 1 second and 73% for forced vital capacity. The PS group demonstrated an average 28% (p < 0.01) improvement in Short-Form 36-Item survey reporting. Electrodiagnostic testing in the PS group revealed a mean 69% (p < 0.05) improvement in conduction latency and a 37% (p < 0.0001) increase in motor amplitude. In the NS group, there was no significant change in Short-Form 36-Item survey or spirometry values.

CONCLUSIONS

Phrenic nerve operations for functional restoration of the paralyzed diaphragm should be part of the standard treatment algorithm in the management of symptomatic patients with this condition. Assessment of neuromuscular dysfunction can aid in determining the most effective therapy.

A novel oxysterol promotes bone regeneration in rabbit cranial bone defects

Bone morphogenetic proteins (BMPs) have played a central role in the development of regenerative therapies for bone reconstruction. However, the high cost and side-effect profile of BMPs limits their broad application. Oxysterols, naturally occurring products of cholesterol oxidation, are promising osteogenic agents alternative to BMPs. The osteogenic capacity of these non-toxic and relatively inexpensive molecules has been documented in rodent models. We studied the impact of Oxy49, a novel oxysterol analogue, on the osteogenic differentiation of rabbit bone marrow stromal cells (BMSCs). Moreover, we evaluated the capacity for in vivo bone regeneration with Oxy49 in rabbit cranial bone defects. We found that rabbit BMSCs treated with Oxy49 demonstrated differentiation along osteogenic pathways, and that complete bone regeneration occurred when cranial defects were treated with Oxy49. Collectively, these results demonstrate that Oxy49 has the ability to induce osteogenic differentiation in rabbit BMSCs with an efficacy comparable to that of BMP-2 and to promote significant bone regeneration in cranial defects. Oxysterols may be a viable novel agent in bone tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd.

Postoperative Medical Complications???-Not Microsurgical Complications???-Negatively Influence the Morbidity, Mortality, and True Costs after Microsurgical Reconstruction for Head and Neck Cancer

BACKGROUND

Immediate reconstruction of composite head and neck defects using free tissue transfer is an accepted treatment standard. There remains, however, ongoing debate on whether the costs associated with this reconstructive approach merit its selection, especially considering poor patient prognoses and the high cost of care.

METHODS

A retrospective review of the last 100 consecutive patients undergoing microsurgical reconstruction for head and neck cancer by the two senior surgeons was performed to determine whether microsurgical complications or postoperative medical complications had the more profound influence on morbidity and mortality outcomes and the true costs of these reconstructions.

RESULTS

Two patients required re-exploration of the microsurgical anastomoses, for a re-exploration rate of 2 percent, and one flap failed, for a flap success rate of 99 percent. The major surgical complication rate requiring a second operative procedure was 6 percent. Sixteen percent had minor surgical complications related to the donor site. Major medical complications, defined as a significant risk to the patient's life, occurred in 5 percent of the patients, but there was a 37 percent incidence of "minor" medical complications primarily caused by pulmonary problems and alcohol withdrawal. Postsurgical complications almost doubled the average hospital stay from 13.5 days for those patients without complications to 24 days for patients with complications. Thirty-six percent of the true cost of microsurgical reconstruction of head and neck cancer was due to the intensive care unit and hospital room costs, and 24 percent was due to operating room costs. Postsurgical complications resulted in a 70.7 percent increase in true costs, reflecting a prolonged stay in the intensive care unit and not an increase in operating room costs or regular hospital room costs.

CONCLUSION

Postoperative medical complications in these elderly, debilitated patients related to pulmonary problems and alcohol withdrawal were statistically far more important in negatively affecting the outcomes and true costs of microsurgical reconstruction.

Osteogenic Potentiation of Human Adipose???Derived Stem Cells in a 3-Dimensional Matrix

Adipose-derived stem cells (ADSCs) hold promise for use in tissue engineering. Despite growing enthusiasm for use of ADSCs, there is limited research that has examined their behavior in different in vitro and in vivo systems. The purpose of our study was to evaluate the effect of the extracellular matrix structure and composition on osteogenic differentiation by comparing the osteogenic marker expression of ADSCs grown under 2-dimensional or 3-dimensional cell culture conditions. Group 1 (2-D) included ADSCs raised under conventional cell culture conditions (cells in a 2-D monolayer configuration) (n = 24), and group 2 (3-dimensional) included ADSCs seeded in a collagen gel (cells within a 3-dimensional, biologically active environment) (n = 24). Comparison of ADSC behavior between the 2 groups was analyzed during a 14-day time frame. Osteogenic marker expression (CBFA-1, alkaline phosphatase, osteonectin, osteopontin, Collagen I, and JNK2) was quantified by real-time PCR, and histologic analysis was performed. Histologically, group 1 (2-D) showed cell spreading and deposition of a calcified extracellular matrix. Group 2 (3-dimensional) assumed a disorganized state in the collagen gel, with extension of pseudopodia throughout the matrix. Expression of CBFA-1 was up-regulated immediately in both groups. However, cells in group 2 (3-dimensional) had a more rapid and greater overall expression compared with cells in group 1 (2-D) (250-fold greater at 4 days). At day 14, cells in group 2 (3-dimensional) showed greater expression of all other osteogenic markers than cells in group 1 (2-D) (2.3-fold greater expression of alkaline phosphatase [P < 0.05], 8.4-fold greater expression of osteonectin [P < 0.05], 6.4-fold greater expression of osteopontin [P < 0.05], 2.9-fold greater expression of collagen I [P < 0.05], and 2.5-fold greater expression of JNK2 [P < 0.05]). Our data showed there was a progressive stimulatory effect on ADSCs with regard to osteogenesis when cultured in a 3-dimensional gel compared with a 2-D monolayer.

Characterization of Growth and Osteogenic Differentiation of Rabbit Bone Marrow Stromal Cells

BACKGROUND

The rabbit is recognized as an excellent model to study the repair of bony defects with tissue engineered constructs. However, the use of rabbit bone marrow stromal cells (RBMSCs) has been limited despite the proven benefits of autologous BMSCs in the formation of bone. The purpose of this study was to characterize the growth and differentiation pattern of RBMSCs and their response to growth factors.

MATERIAL AND METHODS

BMSCs were isolated from New Zealand White rabbits and cultured. Serial cell counts of parallel cultures were taken daily to determine cell growth. Response of RBMSCs to varying doses of recombinant human BMP-2 (rhBMP-2) and their time course was gauged by alkaline phosphatase (ALP) activity. The osteoblastic differentiation potential of RBMSCs in response to rhBMP-2 treatment was determined by evaluating the expression pattern of various genes involved with osteogensis using northern analysis. Von Kossa staining was performed to determine the effect of rhBMP-2 on the mineralization capabilities of RBMSCs.

RESULTS

The growth rate of RBMSCs severely declined after first passage and this rate was further suppressed by TGF-beta1. The optimal dose response of rhBMP-2 was determined to be 50 ng/ml and its time course displayed increasing alkaline phosphatase activity over time. Two osteogenic markers, collagen I and osteopontin, were up regulated by rhBMP-2 treatment. Finally, the mineralization capability of RBMSCs was determined to be enhanced by rhBMP-2 treatment.

CONCLUSION

Our work indicates that RBMSCs possess strong osteogenic potential and can be successfully applied toward bone tissue engineering in a rabbit model.

The application of craniofacial techniques and intracranial endoscopy to pituitary surgery

The evolution of pituitary surgery during the last century is characterized by the development of progressively less invasive approaches to the pituitary gland that have been facilitated by simultaneous advances in medical technology. Once performed via an open transcranial operation involving prolonged brain retraction, resection of pituitary tumors can now be performed via a direct transnasal approach entirely under endoscopic imaging. This review discusses the evolution of pituitary surgery from open transcranial techniques to the fully endoscopic transnasal procedure. However, in certain cases, with large pituitary tumors that have a significant extrasellar portion, a transcranial approach offers the greatest chance of complete tumor removal and often is reserved for the second stage of a two-staged operation. Recently, an endoscopic transglabellar minimally invasive approach has been reported, which could be used in place of the traditional transcranial approach.

Osteogenic differentiation is inhibited and angiogenic expression is enhanced in MC3T3-E1 cells cultured on three-dimensional scaffolds

Osteogenic differentiation of osteoprogenitor cells in three-dimensional (3D) in vitro culture remains poorly understood. Using quantitative real-time RT-PCR techniques, we examined mRNA expression of alkaline phosphatase, osteocalcin, and vascular endothelial growth factor (VEGF) in murine preosteoblastic MC3T3-E1 cells cultured for 48 h and 14 days on conventional two-dimensional (2D) poly(l-lactide-co-glycolide) (PLGA) films and 3D PLGA scaffolds. Differences in VEGF secretion and function between 2D and 3D culture systems were examined using Western blots and an in vitro Matrigel-based angiogenesis assay. Expression of both alkaline phosphatase and osteocalcin in cells cultured on 3D scaffolds was significantly downregulated relative to 2D controls in 48 h and 14 day cultures. In contrast, elevated levels of VEGF expression in 3D culture were noted at every time point in short- and long-term culture. VEGF protein secretion in 3D cultures was triple the amount of secretion observed in 2D controls. Conditioned medium from 3D cultures induced an enhanced level of angiogenic activity, as evidenced by increases in branch points observed in in vitro angiogenesis assays. These results collectively indicate that MC3T3-E1 cells commit to osteogenic differentiation at a slower rate when cultured on 3D PLGA scaffolds and that VEGF is preferentially expressed by these cells when they are cultured in three dimensions.

Craniofacial and skull base trauma

BACKGROUND

Traumatic craniofacial and skull base injuries require a multidisciplinary team approach. Trauma physicians must evaluate carefully, triage properly, and maintain a high index of suspicion to improve survival and enhance functional recovery. Frequently, craniofacial and skull base injuries are overlooked while treating more life-threatening injuries. Unnoticed complex craniofacial and skull base fractures, cerebrospinal fluid fistulae, and cranial nerve injuries can result in blindness, diplopia, deafness, facial paralysis, or meningitis. Early recognition of specific craniofacial and skull base injury patterns can lead to identification of associated injuries and allow for more rapid and appropriate management.

CONCLUSION

Early detection and treatment of craniofacial and skull base traumatic injuries should lead to decreased morbidity and mortality. This review discusses the most common of these injuries, their possible complications, and treatment.

A new powered endoscope holding arm for endoscopic surgery of the cranial base

Over the past 20 years endoscopy has become an essential part of nearly all surgical specialities. In the field of skull base surgery recent articles describe new applications and highlight improved results in pituitary adenoma removal, vascular decompression surgery, and in the resection of many other skull base tumors. The strength of the endoscope in skull base surgery lies in its ability to see behind bony apices and neurovascular structures, which normally obscure the view of the operating microscope. Paramount to the success of the endoscope in skull base and pituitary surgery is the ability to secure the arm in position. Operating in the confined spaces of the skull, the instability and difficult adjustment of currently available endoscope holding arms is cumbersome for the surgeon and dangerous to the patient. Many surgeons have commented that the currently available endoscope holding arms are inadequate for contemporary applications of endoscopic skull base surgery. In this article we describe a new pneumatically powered endoscope holding arm, which provides the level of stability and ease of adjustment necessary for current and future applications of endoscope skull base surgery.