Development of a model to investigate the effects of prolonged ischaemia on the muscles of mastication of male Sprague Dawley rats

OBJECTIVE

The aims of this study were to develop a novel rodent model of masticatory muscle ischaemia via unilateral ligation of the external carotid artery (ECA), and to undertake a preliminary investigation to characterize its downstream effects on mechanosensitivity and cellular features of the masseter and temporalis muscles.

DESIGN

The right ECA of 18 male Sprague-Dawley rats was ligated under general anaesthesia. Mechanical detection thresholds (MDTs) at the masseter and temporalis bilaterally were measured immediately before ECA ligation and after euthanasia at 10-, 20-, and 35-days (n = 6 rats/timepoint). Tissue samples from both muscles and sides were harvested for histological analyses and for assessing changes in the expression of markers of hypoxia and muscle degeneration (Hif-1α, VegfA, and Fbxo32) via real time PCR. Data were analyzed using mixed effect models and non-parametric tests. Statistical significance was set at p < 0.05.

RESULTS

MDTs were higher in the right than left hemiface (p = 0.009) after 20 days. Histological changes indicative of muscle degeneration and fibrosis were observed in the right muscles. Hif-1α, VegfA, and Fbxo32 were more highly expressed in the masseter than temporalis muscles (all p < 0.05). Hif-1α and, VegfA did not change significantly with time in all muscles (all p > 0.05). Fbxo32 expression gradually increased in the right masseter (p = 0.024) and left temporalis (p = 0.05).

CONCLUSIONS

ECA ligation in rats induced hyposensitivity in the homolateral hemiface after 20 days accompanied by tissue degenerative changes. Our findings support the use of this model to study pathophysiologic mechanisms of masticatory muscle ischaemia in larger investigations.

Testicular schistosomiasis: a systematic review of the literature

INTRODUCTION

To consolidate reported information on presentation, diagnosis, and treatment modalities in testicular schistosomiasis (TS) to provide a reference tool for this rare disease.

MATERIALS AND METHODS

A comprehensive PubMed search was performed using PRISMA guidelines, which yielded 21 articles detailing 22 cases of TS.

RESULTS

Testicular schistosomiasis remains a rare disease, presenting at a variety of ages (median age 27). All reports of this condition are associated with exposure to an endemic area. The most common presenting symptoms include nonspecific testicular swelling (54.5%) followed by a testicular mass/nodule (18.4%). Diagnosis relies upon clinical suspicion due to low specificity on laboratory and imaging evaluation, with only 18% of urine evaluations positive for parasitic infection. Final diagnosis was made on biopsy (38.1%), radical orchiectomy (47.6%) or frozen section during partial orchiectomy (14.3%). Treatment included anthelmintic mediation (37%), radical/partial orchiectomy (31%), or some combination of the above.

CONCLUSIONS

This systematic review of individual patient data reveals that while urine tests and imaging may aid in diagnosis, all patients require definitive histologic diagnosis. It is important to obtain a thorough history to elucidate exposure to endemic areas and inform whether biopsy, and subsequent testicular preservation, may be appropriate.

Mechanistic Studies of a Skatole-Forming Glycyl Radical Enzyme Suggest Reaction Initiation via Hydrogen Atom Transfer

Gut microbial decarboxylation of amino acid-derived arylacetates is a chemically challenging enzymatic transformation which generates small molecules that impact host physiology. The glycyl radical enzyme (GRE) indoleacetate decarboxylase from Olsenella uli (Ou IAD) performs the non-oxidative radical decarboxylation of indole-3-acetate (I3A) to yield skatole, a disease-associated metabolite produced in the guts of swine and ruminants. Despite the importance of IAD, our understanding of its mechanism is limited. Here, we characterize the mechanism of Ou IAD, evaluating previously proposed hypotheses of: (1) a Kolbe-type decarboxylation reaction involving an initial 1-e^– oxidation of the carboxylate of I3A or (2) a hydrogen atom abstraction from the α-carbon of I3A to generate an initial carbon-centered radical. Site-directed mutagenesis, kinetic isotope effect experiments, analysis of reactions performed in D₂O, and computational modeling are consistent with a mechanism involving initial hydrogen atom transfer. This finding expands the types of radical mechanisms employed by GRE decarboxylases and non-oxidative decarboxylases, more broadly. Elucidating the mechanism of IAD decarboxylation enhances our understanding of radical enzymes and may inform downstream efforts to modulate this disease-associated metabolism.

A Prospective Pilot Study Investigating Performance of 18F-Fluciclovine PET Imaging for Detection of Prostate Cancer 2 Years Following Primary Partial Gland Cryoablation

Purpose

The goal of partial gland ablation (PGA) is to eradicate focal lesions of clinically significant prostate cancer (csPCa) with minimal adverse impact on functional outcomes. The primary objective of this study is to characterize the performance of 18F-Fluciclovine PET imaging for detection of prostate cancer following PGA.

Materials and Methods

Subjects 2 years following primary partial gland cryoablation (PPGCA) were invited to participate in an IRB-approved study providing they met the following inclusion criteria: a single reported mpMRI region of interest (ROI) concordant with biopsy Gleason Grade Group (GGG) < 4, no gross extra-prostatic extension on mpMRI, and no GGG > 1 or GGG 1 with a core length > 6 mm on contralateral systematic biopsy. 18F-Fluciclovine PET MRI imaging of the prostate was performed followed by in and out-of-field biopsies.

Results

Twenty-seven men who met eligibility criteria participated in the prospective study. In-field and out-of-field csPCa recurrence rate was 7.4% and 22.2%, respectively. The sensitivity and positive predictive value of mpMRI and PET imaging did not reach performance to reliably inform who should undergo prostate biopsy.

Conclusion

At 2 years following PPGCA, the rate of in-field csPCa was exceedingly low indicating a limited role for imaging to inform in-field biopsy decisions. The csPCa detection rate of out-of-field recurrence was 22% which provides an opportunity for imaging to inform out-of-field biopsy decisions. Based on our findings, 18F-Fluciclovine PET MRI cannot be used to inform who should undergo out-of-field prostate biopsy at 2 years following PPGCA.

Influence of the Greater Protein Environment on the Electrostatic Potential in Metalloenzyme Active Sites: The Case of Formate Dehydrogenase

The Mo/W-containing metalloenzyme formate dehydrogenase (FDH) is an efficient and selective natural catalyst that reversibly converts CO₂ to formate under ambient conditions. In this study, we investigate the impact of the greater protein environment on the electrostatic potential (ESP) of the active site. To model the enzyme environment, we used a combination of classical molecular dynamics and multiscale quantum-mechanical (QM)/molecular-mechanical (MM) simulations. We leverage charge shift analysis to systematically construct QM regions and analyze the electronic environment of the active site by evaluating the degree of charge transfer between the core active site and the protein environment. The contribution of the terminal chalcogen ligand to the ESP of the metal center is substantial and dependent on the chalcogen identity, with similar, less negative ESPs for Se and S terminal chalcogens in comparison to O regardless of whether the metal is Mo or W. The orientation of the side chains and conformations of the cofactor also affect the ESP, highlighting the importance of sampling dynamic fluctuations in the protein. Overall, our observations suggest that the terminal chalcogen ligand identity plays an important role in the enzymatic activity of FDH, suggesting opportunities for a rational bioinspired catalyst design.

Evaluation of Bowel Function Following Radical Cystectomy and Urinary Diversion Using Two Validated Questionnaires: What Are the Effects on Quality of Life?

OBJECTIVE

To assess both short- and long-term constipation symptoms and their impact on quality of life in patients who underwent radical cystectomy (RC) with three different types of urinary diversion: orthotopic neobladder (ONB), continent cutaneous diversion (CCD), and ileal conduit (IC).

MATERIALS AND METHODS

The validated Patient Assessment of Constipation Symptoms (PAC-SYM) and Patient Assessment of Constipation Quality of Life (PAC-QOL) questionnaires were administered to all patients at follow-up greater than 30 days from surgery. Clinical and pathological characteristics were prospectively recorded in an institutional review board approved bladder cancer database. Using multivariable linear regression analyses, we determined significant predictors of improved constipation symptoms and quality of life scores.

RESULTS

A total of 198 patients completed 255 PAC-SYM and PAC-QOL questionnaires with a median follow-up time of 1.7 years (IQR: 0.7 - 3.0 years). ONB, CCD, and IC were performed in 78%, 5.5%, and 16.5% of patients, respectively. Higher bowel function scores (i.e. worse symptoms) were noted at 3 months post-operatively, while these scores significantly improved over time for PAC-SYM total score (P = .004), abdominal subscore (P = .001), and rectal subscore (P = .018). On multivariable analysis, we found that patients <70 years old (B -2.1, P = .004), with follow-up >1 year (B -4.8, P = .001), and who received an IC (B -2.4, P = .02) had significantly lower PAC-SYM scores.

CONCLUSION

Patients have few constipation symptoms and are overall satisfied with their bowel function at long-term follow-up after RC. While patients with IC have significantly fewer constipation symptoms compared to those with ONB or CCD, all patients had significant improvement one year after the surgery.

Neoadjuvant Chemotherapy in Variant Histology Bladder Cancer: Current Evidence

The role of neoadjuvant chemotherapy in variant histology bladder cancers has yet to be validated in randomized control trials. Several case series have reported experience with NAC in the setting of variant histology. PATIENT SUMMARY: We reviewed outcomes for patients with variant histology muscle-invasive bladder cancer who received chemotherapy before cystectomy. Outcomes varied significantly in the current literature. The best outcomes are associated with neoadjuvant chemotherapy (NAC) for small cell variants, while there is potential benefit with the use of NAC for squamous cell and adenocarcinoma variants.

Occult Nodal Metastases in Patients Down-Staged to Nonmuscle Invasive Disease Following Neoadjuvant Chemotherapy

OBJECTIVES

To evaluate the risk of occult nodal metastasis in patients with muscle invasive bladder cancer who exhibit a complete or partial clinical response to neoadjuvant chemotherapy (NAC) and assess a potential role for "bladder sparing" management given that the gold standard treatment, radical cystectomy (RC), is associated with high morbidity.

METHODS

We queried the National Cancer Database for bladder cancer from 2004 to 2013 including patients with cT2-4aN0M0 bladder cancer who underwent multiagent NAC followed by RC and pelvic lymphadenectomy and excluding patients with nonurothelial predominant histology and those undergoing partial cystectomy. Student's t test was used to evaluate patients' demographics, presence of co-morbid conditions, and pathologic findings, notably the presence of lymphovascular invasion and variant histology.

RESULTS

We identified 17,917 patients who underwent RC. Of these, 14.9% (n = 2673) received NAC before RC. About 13.1% and 14.5% of patients had complete (ypT0) and partial (ypTa, Tis, and T1) pathologic response, respectively. These 14.7% of cT2, 9.0% of cT3, and 6.9% of cT4 patients exhibited pT0 status on final pathology. And 4.9% of complete and 5.4% of partial responders demonstrated occult nodal metastases. Age, sex, ethnicity, the presence of co-morbidities, LVI, and variant histology were not significantly associated with occult nodal metastasis.

CONCLUSION

While bladder preservation may be a viable option in patients who are carefully selected and closely followed after NAC, patients undergoing NAC may be at risk of occult disease outside of the bladder despite an otherwise clinical complete response diagnosed with cross-sectional imaging, cystoscopy, TURBT, and cytology.

Importance of Nitrogen-Hydrogen Bond pKa in the Catalytic Coupling of Alkenes and Amines by Amidate Tantalum Complexes: A Computational Study

Density functional theory (DFT) was carried out to study the impact of substituents with different electronic properties upon hydrogen transfer as the rate-determining step in the hydroaminoalkylation catalytic cycle in order to determine the character of the hydrogen atom in the transition state. In the transition state of the rate-determining step, an N-methylaniline substrate ligates to Ta and transfers its hydrogen to the α-carbon of a five-membered tantallacycle and a Ta-C bond is thus broken. Study of the activation energy barriers resulting from the different para- and meta-substituted N-methylanilines and their correlation with computed pK_a and bond dissociation free energy (BDFE) values of the N-methylanilines show more obvious correlations between pK_a and ΔG^‡ values. Assessing the asynchronicity parameter (η) for the studied substituents reveals that pK_a is a larger driving force in the rate-determining hydrogen transfer reaction than the BDFE, which suggest a reasonable amount of protic character in the transition state, and possible routes to the design of more active catalysts with greater substrate scope.

Step-by-Step: Fusion-guided prostate biopsy in the diagnosis and surveillance of prostate cancer

Objective:

To provide a step-by-step technique for fusion-guided biopsy for prostate cancer diagnosis and surveillance.

Materials and Methods:

All men with clinical indications for image-guided biopsy undergo 3-Tesla multiparametric magnetic resonance imaging (mpMRI) first. Lesions identified on mpMRI are graded using the Prostate Imaging-Reporting and Data System version 2.0 (PI-RADS v2) grading system. At the time of biopsy, real-time 3-dimensional (3D) transrectal ultrasound (TRUS) imaging is acquired and elastically fused with the mpMRI. Both targeted biopsies of MRI-derived suspicious lesions (PI-RADS 3-5) and systematic 12-core biopsies are performed. Patients without suspicious lesion on mpMRI undergo 3D TRUS-guided biopsy in standard templated fashion. In men placed on active surveillance (AS), prior positive sites are revisited using the trajectory and tracking functions of the fusion biopsy software.

Results:

The advantages of MRI/TRUS fusion biopsy for prostate cancer diagnosis and surveillance are numerous. The 3D model created by elastic fusion of real-time TRUS imaging to mpMRI provides excellent visualization of prostate anatomy. Suspicious lesions on mpMRI can be accurately targeted, increasing detection of clinically significant prostate cancer. Biopsy trajectory visualization provides spatial localization of the trajectory of the cores within the prostate. Systematic biopsies are also taken in addition to targeted cores to minimize the effect of the mpMRI-invisible lesion. Prior positive biopsy sites can be tracked in men on AS.

Conclusions:

Combined, the added benefits of prior lesion identification, adequate mapping of prostate anatomy and suspicious lesions, biopsy-trajectory visualization, tracking of prior positive biopsy sites, and combined targeted and systematic cores may offer the most effective method for prostate cancer diagnosis and surveillance.

Testicular Mesothelioma: An Analysis of Epidemiology, Patient Outcomes, and Prognostic Factors

OBJECTIVES

To characterize demographic features, clinical characteristics, and oncologic outcomes of mesothelioma of the testis.

METHODS

A population based search was performed using the National Cancer Institute's SEER 18 database. Patients diagnosed with malignant mesothelioma of the male genital organs from 1973 to 2015 were identified. Data on patient age, race, tumor laterality, histologic subtype, tumor extent, tumor size, tumor grade, treatment, cause of death, and survival months was collected. Primary outcomes were overall survival (OS) and disease-specific survival (DSS).

RESULTS

A total of 113 patients with testicular mesothelioma were identified. The 5-year OS and DSS for all patients was 49% and 58%, and the 10-year OS and DSS was 33% and 45%, respectively. Biphasic mesotheliomas were associated with worse OS compared to general mesotheliomas and epithelioid subtypes (P = .043 and P = .039, respectively). Median survival time was not reached in patients with T1 disease while OS was 1.7 years and DSS was 1.8 years for patients with T4 disease (OS P = .002, DSS P <.001). Tumors greater than or equal to 4 cm were associated with worse OS and DSS (OS P = .025, DSS P = .047).

CONCLUSION

This rare malignancy has significant mortality, with poor survival associated with biphasic subtypes, higher disease stage, and a critical tumor size cutoff of 4 cm.

Dual Prosthetic Implantation After Radical Cystoprostatectomy and Neobladder: Outcomes of the Inflatable Penile Prosthesis and Artificial Urinary Sphincter in Bladder Cancer Survivors

OBJECTIVES

To determine the impact of radical cystectomy and orthotopic neobladder (NB) diversion on device-related outcomes in patients who undergo subsequent placement of both, an artificial urinary sphincter (AUS) and 3-piece inflatable penile prosthesis.

MATERIALS AND METHODS

Using an institutional prosthetic database, we identified 39 patients who underwent radical cystectomy and NB and subsequent implantation of both prosthetic devices from 2003 to 2017. Patient demographics, perioperative data, and postoperative outcomes including prosthetic infection, mechanical failure, revision surgery, and functional outcomes were examined and compared to an appropriate matched group of patients (n = 48, non-neobladder group).

RESULTS

No intraoperative complications were observed. After median follow-up of 94 months (12-177 months), 1 patient developed an infection of their penile prosthesis and 4 patients developed an erosion of their AUS. In each case, the infection did not involve the other device. Two patients required revision surgery of their penile prosthesis due to mechanical failure (reservoir leak, n = 1; cylinder aneurysm, n = 1). Twenty-one patients underwent elective revision surgery to improve continence (cuff downsizing, n = 18; pressure-regulating balloon exchange, n = 3). There were 6 cases of AUS mechanical failure. No reservoir-related complications such as herniation or erosion were observed. Compared to the control group of non-neobladder patients, there were no significant differences in prosthetic infection, mechanical failure, and revision surgery.

CONCLUSION

The AUS and 3-piece inflatable penile prosthesis can coexist safely in patients with NB without an increased risk of device-related complications.

Eccrine Porocarcinoma: New Insights and a Systematic Review of the Literature

BACKGROUND

Eccrine porocarcinoma (EPC) is a rare cutaneous neoplasm with high potential for morbidity and mortality. Due to its rarity, there is a paucity of data profiling diagnosis, work-up, and management.

OBJECTIVE

To consolidate reported information on demographics, diagnostics, clinical behavior, treatment modalities, and patient outcomes in EPC to provide a reference tool to optimize diagnosis and management.

METHODS

A comprehensive PubMed search was performed from 1963 to November 2017 using PRISMA guidelines. This yielded 155 articles detailing 206 cases of porocarcinoma.

RESULTS

Eccrine porocarcinoma most often presents in elderly patients on the head and neck or lower limbs. Metastatic disease at presentation is not uncommon (22%). Primary tumor location is significantly correlated with presence of metastasis (p = .038). The most common treatment is excision followed by Mohs micrographic surgery (MMS), although the outcomes after MMS were superior to those after surgical excision.

CONCLUSION

This systematic review of individual patient data reveals that all patients should have a histological diagnosis with imaging considered for high-risk cases. Primary tumor location should also be considered in diagnostic and therapeutic decision-making. Although wide local excision (WLE) is currently the first-line treatment, MMS is becoming increasingly used, with evidence indicating improved outcomes as compared to those seen with WLE.

Control of C-H Bond Activation by Mo-Oxo Complexes: pKa or Bond Dissociation Free Energy (BDFE)?

A density functional theory (DFT) study (BMK/6-31+G(d)) was initiated to investigate the activation of benzylic carbon-hydrogen bonds by a molybdenum-oxo complex with a potentially redox noninnocent supporting ligand-a simple mimic of the active species of the enzyme ethylbenzene dehydrogenase (EBDH)-through deprotonation (C-H bond heterolysis) or hydrogen atom abstraction (C-H bond homolysis) routes. Activation free-energy barriers for neutral and anionic Mo-oxo complexes were high, but lower for anionic complexes than neutral complexes. Interesting trends as a function of substituents were observed that indicated significant H^δ+ character in the transition states (TS), which was further supported by the preference for [2 + 2] addition over HAA for most complexes. Hence, it was hypothesized that C-H activation by these EBDH mimics is controlled more by the pK_a than by the bond dissociation free energy of the C-H bond being activated. Therefore, the results suggest promising pathways for designing more efficient and selective catalysts for hydrocarbon oxidation based on EBDH active-site mimics.

Access to all components of scanned mathematical documents by vision-impaired students

Vision-impaired people access documents using screen readers. Electronic documents may contain non-textual components, non-linear components, and multidimensional components, such as mathematical expressions and graphs. These components create a number of accessibility issues for those who use screen readers as assistive technology. The research presented here describes mathematical information retrieval, and accessible and navigable representation of mathematical function graphs as solutions to these issues. Additionally, this research study is about how to present course materials to vision-impaired students, and is not about how to teach them. The system shows promise, given an initial evaluation by a vision-impaired person, and an encouraging review by three blind professionals. The next step is to perform a full evaluation of the system employing a larger number of vision-impaired students.

Incidence and characterization of resistance to pyrethroid and organophosphorus insecticides in Thrips tabaci (Thysanoptera: Thripidae) in onion fields in Isfahan, Iran

Onion thrips, Thrips tabaci Lindeman, is the main pest of onion-growing fields in Isfahan and is mainly controlled by frequently spraying several insecticides. To investigate the resistance status and mechanisms, the susceptibility of ten field populations collected from Isfahan onion-growing regions were tested to several currently used pesticides. Resistance to the tested insecticides was observed in most populations when compared with the susceptible reference population. Enhanced detoxification, implicated by the use of inhibitors of major metabolic detoxification enzymes, was observed in the populations resistant to profenofos and chlorpyrifos. In the deltamethrin resistant populations, the amino acid substitution T929I was detected in the voltage gated sodium channel, which is known to confer pyrethroid resistance. These data are a first step towards more efficient resistance management tactics through early detection of resistant onion thrips in Iran.

Use of ultra-high molecular weight polycaprolactone scaffolds for ACL reconstruction

Previously, we reported on the implantation of electrospun polycaprolactone (PCL) grafts for use in ACL tissue engineering in a small animal model. In the present study, we hypothesized that grafts fabricated from ultra-high molecular weight polycaprolactone (UHMWPCL) would have similarly favorable biologic properties but superior mechanical properties as compared to grafts fabricated from PCL. Two forms of polycaprolactone were obtained (UHMWPCL, MW = 500 kD, and PCL, MW = 80 kD) and electrospun into scaffolds that were used to perform ACL reconstruction in 7-8 week old male Lewis rats. The following groups were examined: UHMWPCL, PCL, flexor digitorum longus (FDL) allograft, native ACL, as well as sham surgery in which the ACL was transsected. At 16 weeks post-operatively, biomechanical testing, histology, and immunohistochemistry (IHC) were performed. Analysis of cellularity indicated that there was no significant difference among the UHMWPCL, PCL, and FDL allograft groups. Quantification of birefringence from picrosirius red staining demonstrated significantly more aligned collagen fibers in the allograft than the PCL group, but no difference between the UHMWPCL and allograft groups. The peak load to failure of the UHMWPCL grafts was significantly higher than PCL, and not significantly different from FDL allograft. This in vivo study establishes the superiority of the higher molecular weight version of polycaprolactone over PCL as a scaffold material for ACL reconstruction. By 16 weeks after implantation, the UHMWPCL grafts were not significantly different from the FDL allografts in terms of cellularity, peak load to failure, stiffness, and collagen fiber alignment. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:828-835, 2016.

Evaluation of polycaprolactone scaffold with basic fibroblast growth factor and fibroblasts in an athymic rat model for anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) rupture is a common ligamentous injury often necessitating surgery. Current surgical treatment options include ligament reconstruction with autograft or allograft, which have their inherent limitations. Thus, there is interest in a tissue-engineered substitute for use in ACL regeneration. However, there have been relatively few in vivo studies to date. In this study, an athymic rat model of ACL reconstruction was used to evaluate electrospun polycaprolactone (PCL) grafts, with and without the addition of basic fibroblast growth factor (bFGF) and human foreskin fibroblasts. We examined the regenerative potential of tissue-engineered ACL grafts using histology, immunohistochemistry, and mechanical testing up to 16 weeks postoperatively. Histology showed infiltration of the grafts with cells, and immunohistochemistry demonstrated aligned collagen deposition with minimal inflammatory reaction. Mechanical testing of the grafts demonstrated significantly higher mechanical properties than immediately postimplantation. Acellular grafts loaded with bFGF achieved 58.8% of the stiffness and 40.7% of the peak load of healthy native ACL. Grafts without bFGF achieved 31.3% of the stiffness and 28.2% of the peak load of healthy native ACL. In this in vivo rodent model study for ACL reconstruction, the histological and mechanical evaluation demonstrated excellent healing and regenerative potential of our electrospun PCL ligament graft.

Athymic rat model for evaluation of engineered anterior cruciate ligament grafts

Anterior cruciate ligament (ACL) rupture is a common ligamentous injury that often requires surgery because the ACL does not heal well without intervention. Current treatment strategies include ligament reconstruction with either autograft or allograft, which each have their associated limitations. Thus, there is interest in designing a tissue-engineered graft for use in ACL reconstruction. We describe the fabrication of an electrospun polymer graft for use in ACL tissue engineering. This polycaprolactone graft is biocompatible, biodegradable, porous, and is comprised of aligned fibers. Because an animal model is necessary to evaluate such a graft, this paper describes an intra-articular athymic rat model of ACL reconstruction that can be used to evaluate engineered grafts, including those seeded with xenogeneic cells. Representative histology and biomechanical testing results at 16 weeks postoperatively are presented, with grafts tested immediately post-implantation and contralateral native ACLs serving as controls. The present study provides a reproducible animal model with which to evaluate tissue engineered ACL grafts, and demonstrates the potential of a regenerative medicine approach to treatment of ACL rupture.

In vitro and in vivo evaluation of heparin mediated growth factor release from tissue-engineered constructs for anterior cruciate ligament reconstruction

Anterior cruciate ligament (ACL) rupture is a common injury often necessitating surgical treatment with graft reconstruction. Due to limitations associated with current graft options, there is interest in a tissue-engineered substitute for use in ACL regeneration. While they represent an important step in translation to clinical practice, relatively few in vivo studies have been performed to evaluate tissue-engineered ACL grafts. In the present study, we immobilized heparin onto electrospun polycaprolactone scaffolds as a means of incorporating basic fibroblast growth factor (bFGF) onto the scaffold. In vitro, we demonstrated that human foreskin fibroblasts (HFFs) cultured on bFGF-coated scaffolds had significantly greater cell proliferation. In vivo, we implanted electrospun polycaprolactone grafts with and without bFGF into athymic rat knees. We analyzed the regenerated ACL using histological methods up to 16 weeks post-implantation. Hematoxylin and eosin staining demonstrated infiltration of the grafts with cells, and picrosirius red staining demonstrated aligned collagen fibers. At 16 weeks postop, mechanical testing of the grafts demonstrated that the grafts had approximately 30% the maximum load to failure of the native ACL. However, there were no significant differences observed between the graft groups with or without heparin-immobilized bFGF. While this study demonstrates the potential of a regenerative medicine approach to treatment of ACL rupture, it also demonstrates that in vitro results do not always predict what will occur in vivo.