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Alonso Torrens A, Mitchell CA, Pourshahidi LK, Murphy BÓ, Allwood W, Rizzetto L, Scholz M, Tuohy K, Pereira-Caro G, Moreno-Rojas JM, McDougall G, Gill CIR. Long-term supplementation with anthocyanin-rich or -poor Rubus idaeus berries does not influence microvascular architecture nor cognitive outcome in the APP/PS-1 mouse model of Alzheimer's disease. Int J Food Sci Nutr 2023; 74:33-50. [PMID: 36450698 DOI: 10.1080/09637486.2022.2141209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Disruption of microvascular architecture is a common pathogenic mechanism in the progression of Alzheimer's disease (AD). Given the anti-angiogenic activity of berry (poly)phenols, we investigated whether long-term feeding of Rubus idaeus (raspberries) could ameliorate cerebral microvascular pathology and improve cognition in the APP/PS-1 mouse model of AD. Male C57Bl/6J mice (50 wild type, 50 APP/PS-1) aged 4-months were fed for 24-weeks, with a normal diet enriched with either 100 mg/day glucose (control diet) or supplemented with glucose and freeze-dried anthocyanin-rich (red) or -poor (yellow) raspberries (100 mg/day) and assessed/sampled post intervention. Cerebral microvascular architecture of wild-type mice was characterised by regularly spaced capillaries with uniform diameters, unlike APP/PS-1 transgenic mice which showed dysregulated microvascular architecture. Long-term feeding of raspberries demonstrated limited modulation of microbiota and no substantive effect on microvascular architecture or cognition in either mice model although changes were evident in endogenous cerebral and plasmatic metabolites.
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Callaghan B, Twigg MS, Baccile N, Van Bogaert INA, Marchant R, Mitchell CA, Banat IM. Microbial sophorolipids inhibit colorectal tumour cell growth in vitro and restore haematocrit in Apc min+/- mice. Appl Microbiol Biotechnol 2022; 106:6003-6016. [PMID: 35965289 PMCID: PMC9467956 DOI: 10.1007/s00253-022-12115-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/27/2022] [Accepted: 07/28/2022] [Indexed: 11/28/2022]
Abstract
Abstract
Sophorolipids are glycolipid biosurfactants consisting of a carbohydrate sophorose head with a fatty acid tail and exist in either an acidic or lactonic form. Sophorolipids are gaining interest as potential cancer chemotherapeutics due to their inhibitory effects on a range of tumour cell lines. Currently, most anti-cancer studies reporting the effects of sophorolipids have focused on lactonic preparations with the effects of acidic sophorolipids yet to be elucidated. We produced a 94% pure acidic sophorolipid preparation which proved to be non-toxic to normal human colonic and lung cells. In contrast, we observed a dose-dependent reduction in viability of colorectal cancer lines treated with the same preparation. Acidic sophorolipids induced apoptosis and necrosis, reduced migration, and inhibited colony formation in all cancer cell lines tested. Furthermore, oral administration of 50 mg kg−1 acidic sophorolipids over 70 days to Apcmin+/− mice was well tolerated and resulted in an increased haematocrit, as well as reducing splenic size and red pulp area. Oral feeding did not affect tumour numbers or sizes in this model. This is the first study to show that acidic sophorolipids dose-dependently and specifically reduces colon cancer cell viability in addition to reducing tumour-associated bleeding in the Apcmin+/− mouse model. Key points • Acidic sophorolipids are produced by yeast species such as Starmerella bombicola. • Acidic sophorolipids selectively killed colorectal cells with no effect on healthy gut epithelia. • Acidic sophorolipids reduced tumour-associated gut bleed in a colorectal mouse model. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1007/s00253-022-12115-6.
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Chen P, Wang A, Haynes W, Landao-Bassonga E, Lee C, Ruan R, Breidahl W, Shiroud Heidari B, Mitchell CA, Zheng M. A bio-inductive collagen scaffold that supports human primary tendon-derived cell growth for rotator cuff repair. J Orthop Translat 2022; 31:91-101. [PMID: 34976729 PMCID: PMC8671806 DOI: 10.1016/j.jot.2021.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 02/05/2023] Open
Abstract
Background Rotator Cuff (RC) tendon tearing is a common clinical problem and there is a high incidence of revision surgery due to re-tearing. In an effort to improve patient outcome and reduce surgical revision, scaffolds have been widely used for augmentation of RC repairs. However, little is known about how scaffolds support tendon stem cell growth or facilitate tendon regeneration. The purpose of this study is to evaluate the structural and biological properties of a bioactive collagen scaffold (BCS) with the potential to promote tendon repair. Additionally, we conducted a pilot clinical study to assess the safety and feasibility of using the BCS for repair of RC tears. Methods A series of physical, ultrastructural, molecular and in vitro tests determined the biocompatibility and teno-inductive properties of this BCS. In addition, a prospective case study of 18 patients with RC tendon tears (>20 mm in diameter) was performed in an open-label, single-arm study, involving either mini-open or arthroscopic surgical RC repair with the BCS. Clinical assessment of RC repair status was undertaken by MRI-imaging at baseline, 6 and 12 months and patient evaluated questionnaires were taken at baseline as well as 3, 6 & 12 months. Results The BCS consists of highly purified type-I collagen, in bundles of varying diameter, arranged in a higher order tri-laminar structure. BCS have minimal immunogenicity, being cell and essentially DNA-free as well as uniformly negative for the porcine α-Gal protein. BCS seeded with human primary tendon-derived cells and exposed to 6% uniaxial loading conditions in vitro, supported increased levels of growth and proliferation as well as up-regulating expression of tenocyte differentiation marker genes including TNMD, Ten-C, Mohawk and Collagen-1α1. To test the safety and feasibility of using the BCS for augmentation of RC repairs, we followed the IDEAL framework and conducted a first, open-label single arm prospective case series study of 18 patients. One patient was withdrawn from the study at 3 months due to wound infection unrelated to the BCS. The remaining 17 cases showed that the BCS is safe to be implanted. The patients reported encouraging improvements in functional outcomes (ASES, OSS and Constant-Murley scores), as well as quality of life assessments (AQoL) and a reduction in VAS pain scores. MRI assessment at 12 months revealed complete healing in 64.8% patients (11/17), 3 partial thickness re-tears (17.6%) and 3 full thickness re-tears (17.6%). Conclusion The BCS is composed of type-I collagen that is free of immunogenic proteins and supports tendon-derived cell growth under mechanical loading in vitro. This pilot study shows that it is safe and feasible to use BCS for RC argumentation and further controlled prospective studies are required to demonstrate its efficacy. The Translational potential of this article The results of this study indicate that this bioactive collagen scaffold has unique properties for supporting tendon growth and that it is non-immunogenic. The clinical study further confirms that the scaffold is a promising biological device for augment of human rotator cuff repairs.
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O’Donnell MT, Kucera J, Mitchell CA, Gurney JM. Mitigating SARS-CoV-2 in the Deployed Environment. Mil Med 2021; 188:e74-e79. [PMID: 34114625 PMCID: PMC8344915 DOI: 10.1093/milmed/usab189] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/18/2021] [Accepted: 05/09/2021] [Indexed: 01/11/2023] Open
Abstract
INTRODUCTION Unlike other communal living environments (universities, boarding schools, and camps) that have been suspended during the COVID-19 pandemic, the deployed military force must continue its mission. Early challenges in the 2020 deployed environment included limited availability of living and quarantine space and limited testing capacity. This is a brief report of stringent quarantine strategies employed to newly arriving cohorts at a NATO and U.S. military base to prevent release of SARS-CoV-2 into a larger base population. METHODS With awareness of the worldwide pandemic, beginning in late February 2020, all personnel arriving to the Hamid Karzai International Airport NATO base were quarantined for 14 days to prevent interaction with the wider base population. Testing capacity was limited. Names, locations, and dates of those within quarantine were tracked to improve contact tracing. Between February and April 2020, the first cases of SARS-CoV-2 were diagnosed on a military base in Afghanistan within quarantine. RESULTS Within quarantine, 11 males became PCR positive for SARS-CoV-2 during April 2020. Five of the 11 were PCR tested for symptoms of fever, cough, or loss of taste. A sixth individual, who had been asymptomatic upon leaving the base after completion of quarantine, later developed symptoms and tested positive. Another five asymptomatic individuals were found with antibody testing just before planned release from 14 days of quarantine post-exposure and confirmed with PCR testing. All PCR-positive individuals were diagnosed before being released into the general population of the base because of strict screening, quarantine, and exit criteria. CONCLUSION Quarantine creates significant strain on resources in a deployed environment. Group quarantine facilities where social distancing is limited allow for the possibility for intra-quarantine transmission of SARS-CoV-2. Ideally, PCR testing is done upon entry into quarantine and upon exit. With the possibility of false-negative PCR or limited PCR testing, we recommend daily symptom screening, pulse oximetry, temperature checks, and small quarantine groups that must "graduate" together-all meeting exit criteria. Any introduction of new individual, even with negative testing, to a group increases risk of SARS-CoV-2 transmission.Upon exit of quarantine, testing should be performed, regardless of entry testing. If PCR is limited, serology testing should be done, followed by PCR, if positive. Serology testing can be combined with clinical judgment to conserve PCR testing for quarantine release of asymptomatic individuals.
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Wang T, Chen P, Chen L, Zhou Y, Wang A, Zheng Q, Mitchell CA, Leys T, Tuan RS, Zheng MH. Reduction of mechanical loading in tendons induces heterotopic ossification and activation of the β-catenin signaling pathway. J Orthop Translat 2021; 29:42-50. [PMID: 34094857 PMCID: PMC8142054 DOI: 10.1016/j.jot.2021.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/15/2021] [Accepted: 03/01/2021] [Indexed: 11/24/2022] Open
Abstract
Background Tendons are the force transferring tissue that enable joint movement. Excessive mechanical loading is commonly considered as a primary factor causing tendinopathy, however, an increasing body of evidence supports the hypothesis that overloading creates microdamage of collagen fibers resulting in a localized decreased loading on the cell population within the damaged site. Heterotopic ossification is a complication of late stage tendinopathy, which can significantly affect the mechanical properties and homeostasis of the tendon. Here, we the examine the effect of mechanical underloading on tendon ossification and investigate its underlying molecular mechanism. Method Rabbit Achilles tendons were dissected and cultured in an underloading environment (3% cyclic tensile stain,0.25 Hz, 8 h/day) for either 10, 15 or 20 days. Using isolated tendon-derived stem cells (TDSCs) 3D constructs were generated, cultured and subjected to an underloading environment for 6 days. Histological assessments were performed to evaluate the structure of the 3D constructs; qPCR and immunohistochemistry were employed to study TDSC differentiation and the β-catenin signal pathway was investigated by Western blotting. Mechanical testing was used to determine ability of the tendon to withstand force generation. Result Tendons cultured for extended times in an environment of underloading showed progressive heterotopic ossification and a reduction in biomechanical strength. qPCR revealed that 3D TDSCs constructs cultured in an underloading environment exhibited increased expression of several osteogenic genes: these include RUNX2, ALP and osteocalcin in comparison to tenogenic differentiation markers (scleraxis and tenomodulin). Immunohistochemical analysis further confirmed high osteocalcin production in 3D TDSCs constructs subject to underloading. Western blotting of TDSC constructs revealed that β-catenin accumulation and translocation were associated with an increase in phosphorylation at Ser552 and decrease phosphorylation at Ser33. Conclusion These findings unveil a potential mechanism for heterotopic ossification in tendinopathy due to the underloading of TDSCs at the damage sites, and also that β-catenin could be a potential target for treating heterotopic ossification in tendons. The Translational potential Tendon heterotopic ossification detrimentally affect quality of life especially for those who has atheletic career. This study reveals the possible mechanism of heterotpic ossification in tendon related to mechanical loading. This study provided the possible to develop a mechanical stimulation protocol for preventive and therapeutic purpose for tendon heterotopic ossification.
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Meadows RM, Monti JD, Umar MA, Van Arnem KA, Chin EJ, Mitchell CA, Love S. US Army Combat Medic Performance With Portable Ultrasound to Detect Sonographic Findings of Pneumothorax in a Cadaveric Model. JOURNAL OF SPECIAL OPERATIONS MEDICINE : A PEER REVIEWED JOURNAL FOR SOF MEDICAL PROFESSIONALS 2020; 20:71-75. [PMID: 32969007 DOI: 10.55460/sopz-stap] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/01/2020] [Indexed: 11/09/2022]
Abstract
BACKGROUND Ultrasound, due to recent advances in portability and versatility, has become a valuable clinical adjunct in austere, resource-limited settings and is well demonstrated to be an accurate/efficient means to detect pneumothorax. The purpose of this study was to evaluate the impact of hands-on ultrasound training on ultrasound-naive US Army combat medics' ability to detect sonographic findings of pneumothorax with portable ultrasound in a cadaver model. METHODS Ultrasound-naive US Army combat medics assigned to conventional military units were recruited from a single US Army installation and randomized to receive either didactic training only, or "blended" (didactic and hands-on) training on ultrasound detection of pneumothorax. Blinded participants were asked to perform a thoracic ultrasound exam on ventilated human cadaver models. Primary outcome measured was sensitivity and specificity of detecting sonographic findings of pneumothorax between cohorts. RESULTS Forty-three participants examined a total of 258 hemithoraces. The didactic-only cohort (n = 24) detected sonographic findings of pneumothorax with a sensitivity of 68% and specificity of 57%. The blended cohort (n = 19) detected sonographic findings of pneumothorax with an overall sensitivity of 91% and specificity of 80%. Detection sensitivities were similar between B-mode versus M-mode use. CONCLUSION US Army combat medics can use portable U/S to detect sonographic findings of pneumothorax in a human cadaver model with high sensitivity after a brief, blended (didactic and hands-on) training intervention.
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Norris E, Ramos-Rivera C, Poologasundarampillai G, Clark JP, Ju Q, Obata A, Hanna JV, Kasuga T, Mitchell CA, Jell G, Jones JR. Electrospinning 3D bioactive glasses for wound healing. Biomed Mater 2020; 15:015014. [DOI: 10.1088/1748-605x/ab591d] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abdelkader DH, Tambuwala MM, Mitchell CA, Osman MA, El-Gizawy SA, Faheem AM, El-Tanani M, McCarron PA. Enhanced cutaneous wound healing in rats following topical delivery of insulin-loaded nanoparticles embedded in poly(vinyl alcohol)-borate hydrogels. Drug Deliv Transl Res 2018; 8:1053-1065. [PMID: 29971752 PMCID: PMC6133079 DOI: 10.1007/s13346-018-0554-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Insulin plays an important role in the wound healing process, but its method of delivery to the wound bed and subsequent effect on rate of healing is less well investigated. In this study, we evaluated the therapeutic effectiveness of topical human insulin delivery using a nanoparticulate delivery system suspended in a structured hydrogel vehicle. Poly(lactide-co-glycolide) (PLGA) nanoparticles (NP) of 202.6 nm diameter and loaded with 33.86 μg insulin per milligram of polymer were formulated using a modified double-emulsion solvent evaporation technique and dispersed in a dilatant hydrogel (poly(vinyl alcohol)-borate). Importantly, this hydrogel formulation was used to achieve ultimate contact with the wound bed. A comparison of wound healing rates following local administration of insulin in the free and nanoencapsulated forms was performed in diabetic and healthy rats. In non-diabetic rats, there was no significant difference between healing observed in control and wounds treated with free insulin (p > 0.05), whereas treatment with insulin encapsulated within PLGA NP showed a significant difference (p < 0.001). In diabetic cohorts, both free insulin and nanoencapsulated insulin induced significant improvement in wound healing when compared to controls, with better percentage wound injury indices observed with the colloidal formulation. At day 10 of the experiment, the difference between percentage wound injury indices of insulin-PLGA NP and free insulin comparing to their controls were 29.15 and 12.16%, respectively. These results support strongly the potential of insulin-loaded colloidal carriers for improved wound healing when delivered using dilatant hydrogel formulations.
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Mitchell CA, Kelemen SM, Salem HH. The Anticoagulant Properties of a Modified Form of Protein S. Thromb Haemost 2018. [DOI: 10.1055/s-0038-1647048] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
SummaryProtein S (PS) is a vitamin K-dependent anticoagulant that acts as a cofactor to activated protein C (APC). To date PS has not been shown to possess anticoagulant activity in the absence of APC.In this study, we have developed monoclonal antibody to protein S and used to purify the protein to homogeneity from plasma. Affinity purified protein S (PSM), although identical to the conventionally purified protein as judged by SDS-PAGE, had significant anticoagulant activity in the absence of APC when measured in a factor Xa recalcification time. Using SDS-PAGE we have demonstrated that prothrombin cleavage by factor X awas inhibited in the presence of PSM. Kinetic analysis of the reaction revealed that PSM competitively inhibited factor X amediated cleavage of prothrombin. PS preincubated with the monoclonal antibody, acquired similar anticoagulant properties. These results suggest that the interaction of the monoclonal antibody with PS results in an alteration in the protein exposing sites that mediate the observed anticoagulant effect. Support that the protein was altered was derived from the observation that PSM was eight fold more sensitive to cleavage by thrombin and human neutrophil elastase than conventionally purified protein S.These observations suggest that PS can be modified in vitro to a protein with APC-independent anticoagulant activity and raise the possibility that a similar alteration could occur in vivo through the binding protein S to a cellular or plasma protein.
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Kelly P, Denver P, Satchell SC, Ackermann M, Konerding MA, Mitchell CA. Microvascular ultrastructural changes precede cognitive impairment in the murine APPswe/PS1dE9 model of Alzheimer's disease. Angiogenesis 2017; 20:567-580. [PMID: 28741167 PMCID: PMC5660145 DOI: 10.1007/s10456-017-9568-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 07/18/2017] [Indexed: 01/04/2023]
Abstract
Cerebral and systemic organ microvascular pathologies coexist with human Alzheimer's disease (AD) neuropathology. In this study, we hypothesised that both cerebral and systemic microvascular pathologies exist in 4- to 5-month-old male APPswe/PS1dE9 (APP/PS1) transgenic mice prior to the onset of cognitive impairment. To assess this we examined recognition memory in both wild-type and APP/PS1 mice using the object recognition task (ORT; n = 11 per group) and counted thioflavin-S-positive plaques in brain (n = 6 per group). Vascular casts of brain, liver, spleen and kidneys were examined using scanning electron microscopy (n = 6 per group), and the urinary albumin-to-creatinine ratio (uACR; n = 5 per group) was measured as an index of glomerular permeability. Murine recognition memory was intact, as demonstrated by a significant preference for the novel object in the ORT paradigm. Brain sections of wild-type mice were devoid of thioflavin-S positivity, whereas age-matched APP/PS1 mice had an average of 0.88 ± 0.22 thioflavin-S-positive plaques in the cortex, 0.42 ± 0.17 plaques in the dentate gyrus and 0.30 ± 0.07 plaques in the cornus ammonis 1 region. The profiles of casted cerebral capillaries of wild-type mice were smooth and regular in contrast to those of APP/PS1 mice which demonstrate characteristic (0.5-4.6 μm) 'tags'. APP/PS1 mice also had a significantly reduced hepatic vessel number (p = 0.0002) and an increase in the number of splenic microvascular pillars (p = 0.0231), in the absence of changes in either splenic microvascular density (p = 0.3746) or glomerular ultrastructure. The highly significant reduction in uACR in APP/PS1 mice compared to wild-type (p = 0.0079) is consistent with glomerular microvascular dysfunction. These findings highlight early microvascular pathologies in 4- to 5-month-old APP/PS1 transgenic mice and may indicate an amenable target for pharmacological intervention in AD.
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Nommeots-Nomm A, Labbaf S, Devlin A, Todd N, Geng H, Solanki AK, Tang HM, Perdika P, Pinna A, Ejeian F, Tsigkou O, Lee PD, Esfahani MHN, Mitchell CA, Jones JR. Highly degradable porous melt-derived bioactive glass foam scaffolds for bone regeneration. Acta Biomater 2017; 57:449-461. [PMID: 28457960 DOI: 10.1016/j.actbio.2017.04.030] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/21/2017] [Accepted: 04/25/2017] [Indexed: 10/19/2022]
Abstract
A challenge in using bioactive melt-derived glass in bone regeneration is to produce scaffolds with interconnected pores while maintaining the amorphous nature of the glass and its associated bioactivity. Here we introduce a method for creating porous melt-derived bioactive glass foam scaffolds with low silica content and report in vitro and preliminary in vivo data. The gel-cast foaming process was adapted, employing temperature controlled gelation of gelatin, rather than the in situ acrylic polymerisation used previously. To form a 3D construct from melt derived glasses, particles must be fused via thermal processing, termed sintering. The original Bioglass® 45S5 composition crystallises upon sintering, altering its bioactivity, due to the temperature difference between the glass transition temperature and the crystallisation onset being small. Here, we optimised and compared scaffolds from three glass compositions, ICIE16, PSrBG and 13-93, which were selected due to their widened sintering windows. Amorphous scaffolds with modal pore interconnect diameters between 100-150µm and porosities of 75% had compressive strengths of 3.4±0.3MPa, 8.4±0.8MPa and 15.3±1.8MPa, for ICIE16, PSrBG and 13-93 respectively. These porosities and compressive strength values are within the range of cancellous bone, and greater than previously reported foamed scaffolds. Dental pulp stem cells attached to the scaffold surfaces during in vitro culture and were viable. In vivo, the scaffolds were found to regenerate bone in a rabbit model according to X-ray micro tomography imaging. STATEMENT OF SIGNIFICANCE This manuscript describes a new method for making scaffolds from bioactive glasses using highly bioactive glass compositions. The glass compositions have lower silica content that those that have been previously made into amorphous scaffolds and they have been designed to have similar network connectivity to that of the original (and commercially used) 45S5 Bioglass. The aim was to match Bioglass' bioactivity. The scaffolds retain the amorphous nature of bioactive glass while having an open pore structure and compressive strength similar to porous bone (the original 45S5 Bioglass crystallises during sintering, which can cause reduced bioactivity or instability). The new scaffolds showed unexpectedly rapid bone regeneration in a rabbit model.
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Geng H, Poologasundarampillai G, Todd N, Devlin-Mullin A, Moore KL, Golrokhi Z, Gilchrist JB, Jones E, Potter RJ, Sutcliffe C, O'Brien M, Hukins DWL, Cartmell S, Mitchell CA, Lee PD. Biotransformation of Silver Released from Nanoparticle Coated Titanium Implants Revealed in Regenerating Bone. ACS APPLIED MATERIALS & INTERFACES 2017; 9:21169-21180. [PMID: 28581710 DOI: 10.1021/acsami.7b05150] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Antimicrobial silver nanoparticle coatings have attracted interest for reducing prosthetic joint infection. However, few studies report in vivo investigations of the biotransformation of silver nanoparticles within the regenerating tissue and its impact on bone formation. We present a longitudinal investigation of the osseointegration of silver nanoparticle-coated additive manufactured titanium implants in rat tibial defects. Correlative imaging at different time points using nanoscale secondary ion mass spectrometry, transmission electron microscopy (TEM), histomorphometry, and 3D X-ray microcomputed tomography provided quantitative insight from the nano- to macroscales. The quality and quantity of newly formed bone is comparable between the uncoated and silver coated implants. The newly formed bone demonstrates a trabecular morphology with bone being located at the implant surface, and at a distance, at two weeks. Nanoscale elemental mapping of the bone-implant interface showed that silver was present primarily in the osseous tissue and colocalized with sulfur. TEM revealed silver sulfide nanoparticles in the newly regenerated bone, presenting strong evidence that the previously in vitro observed biotransformation of silver to silver sulfide occurs in vivo.
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Conduit SE, Ramaswamy V, Remke M, Watkins DN, Wainwright BJ, Taylor MD, Mitchell CA, Dyson JM. A compartmentalized phosphoinositide signaling axis at cilia is regulated by INPP5E to maintain cilia and promote Sonic Hedgehog medulloblastoma. Oncogene 2017. [PMID: 28650469 DOI: 10.1038/onc.2017.208] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Sonic Hedgehog (SHH) signaling at primary cilia drives the proliferation and progression of a subset of medulloblastomas, the most common malignant paediatric brain tumor. Severe side effects associated with conventional treatments and resistance to targeted therapies has led to the need for new strategies. SHH signaling is dependent on primary cilia for signal transduction suggesting the potential for cilia destabilizing mechanisms as a therapeutic target. INPP5E is an inositol polyphosphate 5-phosphatase that hydrolyses PtdIns(4,5)P2 and more potently, the phosphoinositide (PI) 3-kinase product PtdIns(3,4,5)P3. INPP5E promotes SHH signaling during embryonic development via PtdIns(4,5)P2 hydrolysis at cilia, that in turn regulates the cilia recruitment of the SHH suppressor GPR161. However, the role INPP5E plays in cancer is unknown and the contribution of PI3-kinase signaling to cilia function is little characterized. Here, we reveal INPP5E promotes SHH signaling in SHH medulloblastoma by negatively regulating a cilia-compartmentalized PI3-kinase signaling axis that maintains primary cilia on tumor cells. Conditional deletion of Inpp5e in a murine model of constitutively active Smoothened-driven medulloblastoma slowed tumor progression, suppressed cell proliferation, reduced SHH signaling and promoted tumor cell cilia loss. PtdIns(3,4,5)P3, its effector pAKT and the target pGSK3β, which when non-phosphorylated promotes cilia assembly/stability, localized to tumor cell cilia. The number of PtdIns(3,4,5)P3/pAKT/pGSK3β-positive cilia was increased in cultured Inpp5e-null tumor cells relative to controls. PI3-kinase inhibition or expression of wild-type, but not catalytically inactive HA-INPP5E partially rescued cilia loss in Inpp5e-null tumor cells in vitro. INPP5E mRNA and copy number were reduced in human SHH medulloblastoma compared to other molecular subtypes and consistent with the murine model, reduced INPP5E was associated with improved overall survival. Therefore our study identifies a compartmentalized PtdIns(3,4,5)P3/AKT/GSK3β signaling axis at cilia in SHH-dependent medulloblastoma that is regulated by INPP5E to maintain tumor cell cilia, promote SHH signaling and thereby medulloblastoma progression.
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Devlin-Mullin A, Todd NM, Golrokhi Z, Geng H, Konerding MA, Ternan NG, Hunt JA, Potter RJ, Sutcliffe C, Jones E, Lee PD, Mitchell CA. Atomic Layer Deposition of a Silver Nanolayer on Advanced Titanium Orthopedic Implants Inhibits Bacterial Colonization and Supports Vascularized de Novo Bone Ingrowth. Adv Healthc Mater 2017; 6. [PMID: 28321991 DOI: 10.1002/adhm.201700033] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 02/01/2017] [Indexed: 11/10/2022]
Abstract
Joint replacement surgery is associated with significant morbidity and mortality following infection with either methicillin-resistant Staphylococcus aureus (MRSA) or Staphylococcus epidermidis. These organisms have strong biofilm-forming capability in deep wounds and on prosthetic surfaces, with 103 -104 microbes resulting in clinically significant infections. To inhibit biofilm formation, we developed 3D titanium structures using selective laser melting and then coated them with a silver nanolayer using atomic layer deposition. On bare titanium scaffolds, S. epidermidis growth was slow but on silver-coated implants there were significant further reductions in both bacterial recovery (p < 0.0001) and biofilm formation (p < 0.001). MRSA growth was similarly slow on bare titanium scaffolds and not further affected by silver coating. Ultrastructural examination and viability assays using either human bone or endothelial cells, demonstrated strong adherence and growth on titanium-only or silver-coated implants. Histological, X-ray computed microtomographic, and ultrastructural analyses revealed that silver-coated titanium scaffolds implanted into 2.5 mm defects in rat tibia promoted robust vascularization and conspicuous bone ingrowth. We conclude that nanolayer silver of titanium implants significantly reduces pathogenic biofilm formation in vitro, facilitates vascularization and osseointegration in vivo making this a promising technique for clinical orthopedic applications.
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Callaghan B, Lydon H, Roelants SLKW, Van Bogaert INA, Marchant R, Banat IM, Mitchell CA. Lactonic Sophorolipids Increase Tumor Burden in Apcmin+/- Mice. PLoS One 2016; 11:e0156845. [PMID: 27271048 PMCID: PMC4894592 DOI: 10.1371/journal.pone.0156845] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 05/20/2016] [Indexed: 11/18/2022] Open
Abstract
Sophorolipids (SL) are amphiphilic biosurfactant molecules consisting of a disaccharide sophorose with one fatty acid at the C1 position and optional acetylation at the C6’and C6” positions. They exist in a closed ring lactonic (LSL) or open acidic (ASL) structure Sophorolipids are produced in crude mixtures in economically viable amounts by the yeast Starmerella bombicola and used in a variety of consumer products. Varying levels of anti- proliferative and anti-cancer activity of crude sophorolipid mixtures are described in a number of tumor cell lines in vitro. However, significant inter-study variation exists in the composition of sophorolipid species as well as other biologically active compounds in these mixtures, which makes interpretation of in vitro and in vivo studies difficult. We produced a 96% pure C18:1 lactonic sophorolipid that dose-dependently reduces the viability of colorectal cancer, as well as normal human colonic and lung cell lines in vitro. Oral administration of vehicle-only; or lactonic sophorolipids (50 mg/kg for 70 days), to Apcmin+/- mice resulted in an increase in the number (55.5 ± 3.3 vs 70.50 ± 7.8: p < 0.05) and size (modal size 2mm vs 4mm) of intestinal polyps. Lactonic administration resulted in a systematic effect via reduced hematocrit (49.5 ± 1.0 vs 28.2 ± 2.0 vs: p<0.03) and splenomegaly (0.56 ± 0.03g vs 0.71 ± 0.04g; p<0.01) confirming exacerbation of disease progression in this model.
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Geng H, Todd NM, Devlin-Mullin A, Poologasundarampillai G, Kim TB, Madi K, Cartmell S, Mitchell CA, Jones JR, Lee PD. A correlative imaging based methodology for accurate quantitative assessment of bone formation in additive manufactured implants. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2016; 27:112. [PMID: 27153828 PMCID: PMC4859838 DOI: 10.1007/s10856-016-5721-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 04/25/2016] [Indexed: 05/30/2023]
Abstract
A correlative imaging methodology was developed to accurately quantify bone formation in the complex lattice structure of additive manufactured implants. Micro computed tomography (μCT) and histomorphometry were combined, integrating the best features from both, while demonstrating the limitations of each imaging modality. This semi-automatic methodology registered each modality using a coarse graining technique to speed the registration of 2D histology sections to high resolution 3D μCT datasets. Once registered, histomorphometric qualitative and quantitative bone descriptors were directly correlated to 3D quantitative bone descriptors, such as bone ingrowth and bone contact. The correlative imaging allowed the significant volumetric shrinkage of histology sections to be quantified for the first time (~15 %). This technique demonstrated the importance of location of the histological section, demonstrating that up to a 30 % offset can be introduced. The results were used to quantitatively demonstrate the effectiveness of 3D printed titanium lattice implants.
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Mitchell CA, Donaldson M, Francese S, Clench MR. MALDI MSI analysis of lipid changes in living skin equivalents in response to emollient creams containing palmitoylethanolamide. Methods 2016; 104:93-100. [PMID: 26845462 DOI: 10.1016/j.ymeth.2016.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/26/2016] [Accepted: 02/01/2016] [Indexed: 01/17/2023] Open
Abstract
Mass spectrometry imaging (MSI) is a powerful tool for the study of intact tissue sections. The use of matrix-assisted laser desorption/ionisation (MALDI) MSI for the study of the distribution and effect of emollient treatment on sections of reconstructed living skin equivalents during their development and maturation is described. Living skin equivalent (LSE) samples were obtained at 14days development, re-suspended in maintenance medium and incubated for 24h after delivery. The medium was changed, the LSE treated with either Physiogel A.I.® or Oilatum Junior® emollients and then re-incubated and samples taken at 4, 6 and 24h time points. Mass spectra and mass spectral images were recorded from 12μm sections of the LSE taken at each time point for comparison using MALDI mass spectrometry (MS). It was possible to detect ions characteristic of each emollient in the LSE. In addition a number of lipid species previously reported as being significant in the maturation of the LSE were observable. At the 24h time point, the images revealed what appeared to be differences in the organisation of the skin cells observed across the Physiogel A.I.® treatment group tissue sections when directly compared to the untreated tissue group.
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Kelly P, McClean PL, Ackermann M, Konerding MA, Hölscher C, Mitchell CA. Restoration of cerebral and systemic microvascular architecture in APP/PS1 transgenic mice following treatment with Liraglutide™. Microcirculation 2015; 22:133-45. [PMID: 25556713 DOI: 10.1111/micc.12186] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 12/23/2014] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Cerebral microvascular impairments occurring in AD may reduce Aβ peptide clearance and impact upon circulatory ultrastructure and function. We hypothesized that microvascular pathologies occur in organs responsible for systemic Aβ peptide clearance in a model of AD and that Liraglutide (Victoza(®)) improves vessel architecture. METHODS Seven-month-old APP/PS1 and age-matched wild-type mice received once-daily intraperitoneal injections of either Liraglutide or saline (n = 4 per group) for eight weeks. Casts of cerebral, splenic, hepatic, and renal microanatomy were analyzed using SEM. RESULTS Casts from wild-type mice showed regularly spaced microvasculature with smooth lumenal profiles, whereas APP/PS1 mice revealed evidence of microangiopathies including cerebral microanuerysms, intracerebral microvascular leakage, extravasation from renal glomerular microvessels, and significant reductions in both splenic sinus density (p = 0.0286) and intussusceptive microvascular pillars (p = 0.0412). Quantification of hepatic vascular ultrastructure in APP/PS1 mice revealed that vessel parameters (width, length, branching points, intussusceptive pillars and microaneurysms) were not significantly different from wild-type mice. Systemic administration of Liraglutide reduced the incidence of cerebral microanuerysms and leakage, restored renal microvascular architecture and significantly increased both splenic venous sinus number (p = 0.0286) and intussusceptive pillar formation (p = 0.0129). CONCLUSION Liraglutide restores cerebral, splenic, and renal architecture in APP/PS1 mice.
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Mitchell CA, Long H, Donaldson M, Francese S, Clench MR. Lipid changes within the epidermis of living skin equivalents observed across a time-course by MALDI-MS imaging and profiling. Lipids Health Dis 2015; 14:84. [PMID: 26243140 PMCID: PMC4525729 DOI: 10.1186/s12944-015-0089-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 07/27/2015] [Indexed: 11/10/2022] Open
Abstract
Background Mass spectrometry imaging (MSI) is a powerful tool for the study of intact tissue sections. Here, its application to the study of the distribution of lipids in sections of reconstructed living skin equivalents during their development and maturation is described. Methods Living skin equivalent (LSE) samples were obtained at 14 days development, re-suspended in maintenance medium and incubated for 24 h after delivery. The medium was then changed, the LSE re-incubated and samples taken at 4, 6 and 24 h time points. Mass spectra and mass spectral images were recorded from 12 μm sections of the LSE taken at each time point for comparison using matrix assisted laser desorption ionisation mass spectrometry. Results A large number of lipid species were identified in the LSE via accurate mass-measurement MS and MSMS experiments carried out directly on the tissue sections. MS images acquired at a spatial resolution of 50 μm × 50 μm showed the distribution of identified lipids within the developing LSE and changes in their distribution with time. In particular development of an epidermal layer was observable as a compaction of the distribution of phosphatidylcholine species. Conclusions MSI can be used to study changes in lipid composition in LSE. Determination of the changes in lipid distribution during the maturation of the LSE will assist in the identification of treatment responses in future investigations. Electronic supplementary material The online version of this article (doi:10.1186/s12944-015-0089-z) contains supplementary material, which is available to authorized users.
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Callaghan B, Roelants S, Baccile N, Lydon H, Van Bogaert I, Banat IM, Marchant R, Mitchell CA. Abstract 2294: Sophorolipid-mediated inhibition of colorectal tumor cell growth in vitro and in vivo. Cancer Res 2015. [DOI: 10.1158/1538-7445.am2015-2294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: Sophorolipids (SL), are amphiphilic biosurfactant molecules which consist of a sophorose molecule with 2 variable chain length (C10 - C22) They contain double bonds at the 3” 4” positions and fatty acids at the 1” positions. SL exist in either a lactonic (SLL; open ring) or acidic (SLA; closed ring) forms. SL is produced in crude mixtures by the yeast Candidia bombicola in economically viable amounts, with variable levels of anti-proliferative activity on tumour cell lines in vitro. As biosurfactants are well tolerated in the GI tract and currently used in a variety of food products, we tested the hypotheses that purified forms of either SLL or SLA have differential effects on colo-rectal tumour versus “normal” cells as well as in a well-established model of pre-cancerous lesions; viz the Apcmin+/− mouse.
Methodology: The colo-rectal cancer cell lines HT29, HT115, HCT116, Caco-2 in addition to CCD-841 colonic epithelium and MRC5 lung fibroblasts were exposed to 10 - 100 μg/ml of either SLL or SLA (96% or 94%) pure respectively by HPLC/MS analysis) for 24 hours following serum starvation and an MTT assay performed. The mechanism of cell death in cell lines was assessed by acridine orange/ethidium bromide staining followed by microscopic examination. Five-week old APCmin+ mice or wild-type littermate mice were treated orally with 50mg/kg of either SLL or SLA, or vehicle-only control every other day for 14 weeks. Weights, water and food consumption were measured on a daily basis. On completion of the experiment, mice were euthanized, the digestive tract was excised, washed and fixed with 10% BFS. Polyp size, number and location were recorded and samples were blocked for paraffin embedding, sectioning and H&E/immunofluorescence staining and analysis.
Results and Discussion: In vitro, SLL caused a decrease in colorectal cancer cell viability at >70μg/ml. However, it also caused an unfavourable effect on the colonic epithelium and lung fibroblast cell lines by reducing cell viability at a lower concentration (<10μg/ml). In-vivo, SLL treatment exacerbated the growth of polyps along the digestive tract of APCmin+ mice. SLL treatment resulted in an increase in polyp number and size compared to vehicle treated APCmin+ mice. SLL treated mice presented with reduced haematocrits (28.5% vs 34.5% p<0.03) and increased spleen weights (0.56g vs 0.70g p<0.01) compared to vehicle treated control APCmin+ mice.
SLA induced a dose dependent decrease in cell viability of colo-rectal cancer cell lines (20μg/ml) without affecting the viability of the colonic epithelial and lung cell lines. SLA selectively induced cell death in the colo-rectal cancer cells by means of necrosis. However the effects of SLA in vivo are yet to be established.
Contrary to current literature, purified SLA appears to have an advantage over the SLL form in vitro. To date, this is the first study investigating anti-cancer effects of sophorolipids in vivo.
Citation Format: Breedge Callaghan, Sophie Roelants, Niki Baccile, Helen Lydon, Inge Van Bogaert, Ibrahim M. Banat, Roger Marchant, Christopher A. Mitchell. Sophorolipid-mediated inhibition of colorectal tumor cell growth in vitro and in vivo. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2294. doi:10.1158/1538-7445.AM2015-2294
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Strommen JJ, Waterman SM, Mitchell CA, Grogan BF. 2014 Fort Hood, Texas, mass casualty incident: reviews and perspectives. Curr Rev Musculoskelet Med 2015; 8:298-303. [PMID: 26081589 DOI: 10.1007/s12178-015-9287-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
On April 2, 2014, in Fort Hood, Texas, an active shooter incident occurred where four active duty soldiers were tragically killed. Active shooter incidents are becoming alarmingly more frequent over the last decade in the USA. The authors provide a detailed account of the events that occurred within the hospital and an evaluation of the triage decisions made on that day. A detailed review of mass casualty preparedness and the general approach to triage processes are also described.
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McGregor JE, Mitchell CA, Hartell NA. Post-processing strategies in image scanning microscopy. Methods 2015; 88:28-36. [PMID: 25962644 DOI: 10.1016/j.ymeth.2015.05.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 04/06/2015] [Accepted: 05/03/2015] [Indexed: 10/23/2022] Open
Abstract
Image scanning microscopy (ISM) coupled with pixel reassignment offers a resolution improvement of √2 over standard widefield imaging. By scanning point-wise across the specimen and capturing an image of the fluorescent signal generated at each scan position, additional information about specimen structure is recorded and the highest accessible spatial frequency is doubled. Pixel reassignment can be achieved optically in real time or computationally a posteriori and is frequently combined with the use of a physical or digital pinhole to reject out of focus light. Here, we simulate an ISM dataset using a test image and apply standard and non-standard processing methods to address problems typically encountered in computational pixel reassignment and pinholing. We demonstrate that the predicted improvement in resolution is achieved by applying standard pixel reassignment to a simulated dataset and explore the effect of realistic displacements between the reference and true excitation positions. By identifying the position of the detected fluorescence maximum using localisation software and centring the digital pinhole on this co-ordinate before scaling around translated excitation positions, we can recover signal that would otherwise be degraded by the use of a pinhole aligned to an inaccurate excitation reference. This strategy is demonstrated using experimental data from a multiphoton ISM instrument. Finally we investigate the effect that imaging through tissue has on the positions of excitation foci at depth and observe a global scaling with respect to the applied reference grid. Using simulated and experimental data we explore the impact of a globally scaled reference on the ISM image and, by pinholing around the detected maxima, recover the signal across the whole field of view.
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Midha S, van den Bergh W, Kim TB, Lee PD, Jones JR, Mitchell CA. Bioactive glass foam scaffolds are remodelled by osteoclasts and support the formation of mineralized matrix and vascular networks in vitro. Adv Healthc Mater 2013. [PMID: 23184651 DOI: 10.1002/adhm.201200140] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Remodelling of scaffolds and new bone formation is critical for effective bone regeneration. Herein is reported the first demonstration of resorption pits due to osteoclast activity on the surface of sol-gel bioactive glass foam scaffolds. Bioactive glass foam scaffolds are known to have osteogenic potential and suitable pore networks for bone regeneration. Degradation of the scaffolds is known to be initially solution mediated, but for effective bone regeneration, remodelling of the scaffold by osteoclasts and vascularisation of the scaffold is necessary. The culture of C7 macrophages on a bioactive glass scaffold induces the cells to differentiate into (TRAP(+ve) ) osteoclasts. They then form distinctive resorption pits within 3 weeks, while MC3T3-E1 pre-osteoblasts deposit mineralized osteoid on their surfaces in co-culture. The scaffolds are of the 70S30C (70 mol% SiO2 , 30 mol% CaO) composition, with modal pore and interconnect diameters of 373 μm and 172 μm respectively (quantified by X-ray micro-tomography and 3D image analysis). The release of soluble silica and calcium ions from 70S30C scaffolds induces an increase in osteoblast numbers as determined via the MTT assay. Scaffolds also support growth of endothelial cells on their surface and tube formation (characteristic of functional microvasculature) following 4 days in culture. This data supports the hypothesis that 70S30C bioactive glass scaffolds promote the differentiation of the 3 main cell types involved in vascularized bone regeneration.
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Ming L, Byrne NM, Camac SN, Mitchell CA, Ward C, Waugh DJ, McKeown SR, Worthington J. Androgen deprivation results in time-dependent hypoxia in LNCaP prostate tumours: informed scheduling of the bioreductive drug AQ4N improves treatment response. Int J Cancer 2012; 132:1323-32. [PMID: 22915157 DOI: 10.1002/ijc.27796] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 07/06/2012] [Indexed: 02/01/2023]
Abstract
Androgen withdrawal induces hypoxia in androgen-sensitive tissue; this is important as in the tumour microenvironment, hypoxia is known to drive malignant progression. Our study examined the time-dependent effect of androgen deprivation therapy (ADT) on tumour oxygenation and investigated the role of ADT-induced hypoxia on malignant progression in prostate tumours. LNCaP xenografted tumours were treated with anti-androgens and tumour oxygenation measured. Dorsal skin fold (DSF) chambers were used to image tumour vasculature in vivo. Quantitative PCR (QPCR) identified differential gene expression following treatment with bicalutamide. Bicalutamide-treated and vehicle-only-treated tumours were re-established in vitro, and invasion and sensitivity to docetaxel were measured. Tumour growth delay was calculated following treatment with bicalutamide combined with the bioreductive drug AQ4N. Tumour oxygenation measurements showed a precipitate decrease following initiation of ADT. A clinically relevant dose of bicalutamide (2 mg/kg/day) decreased tumour oxygenation by 45% within 24 hr, reaching a nadir of 0.09% oxygen (0.67 ± 0.06 mmHg) by Day 7; this persisted until Day 14 when it increased up to Day 28. Using DSF chambers, LNCaP tumours treated with bicalutamide showed loss of small vessels at Days 7 and 14 with revascularisation occurring by Day 21. QPCR showed changes in gene expression consistent with the vascular changes and malignant progression. Cells from bicalutamide-treated tumours were more malignant than vehicle-treated controls. Combining bicalutamide with AQ4N (50 mg/kg, single dose) caused greater tumour growth delay than bicalutamide alone. Our study shows that bicalutamide-induced hypoxia selects for cells that show malignant progression; targeting hypoxic cells may provide greater clinical benefit.
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McDougall SR, Watson MG, Devlin AH, Mitchell CA, Chaplain MAJ. A hybrid discrete-continuum mathematical model of pattern prediction in the developing retinal vasculature. Bull Math Biol 2012; 74:2272-314. [PMID: 22829182 DOI: 10.1007/s11538-012-9754-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 07/03/2012] [Indexed: 01/26/2023]
Abstract
Pathological angiogenesis has been extensively explored by the mathematical modelling community over the past few decades, specifically in the contexts of tumour-induced vascularisation and wound healing. However, there have been relatively few attempts to model angiogenesis associated with normal development, despite the availability of animal models with experimentally accessible and highly ordered vascular topologies: for example, growth and development of the vascular plexus layers in the murine retina. The current study aims to address this issue through the development of a hybrid discrete-continuum mathematical model of the developing retinal vasculature in neonatal mice that is closely coupled with an ongoing experimental programme. The model of the functional vasculature is informed by a range of morphological and molecular data obtained over a period of several days, from 6 days prior to birth to approximately 8 days after birth. The spatio-temporal formation of the superficial retinal vascular plexus (RVP) in wild-type mice occurs in a well-defined sequence. Prior to birth, astrocytes migrate from the optic nerve over the surface of the inner retina in response to a chemotactic gradient of PDGF-A, formed at an earlier stage by migrating retinal ganglion cells (RGCs). Astrocytes express a variety of chemotactic and haptotactic proteins, including VEGF and fibronectin (respectively), which subsequently induce endothelial cell sprouting and modulate growth of the RVP. The developing RVP is not an inert structure; however, the vascular bed adapts and remodels in response to a wide variety of metabolic and biomolecular stimuli. The main focus of this investigation is to understand how these interacting cellular, molecular, and metabolic cues regulate RVP growth and formation. In an earlier one-dimensional continuum model of astrocyte and endothelial migration, we showed that the measured frontal velocities of the two cell types could be accurately reproduced by means of a system of five coupled partial differential equations (Aubert et al. in Bull. Math. Biol. 73:2430-2451, 2011). However, this approach was unable to generate spatial information and structural detail for the entire retinal surface. Building upon this earlier work, a more realistic two-dimensional hybrid PDE-discrete model is derived here that tracks the migration of individual astrocytes and endothelial tip cells towards the outer retinal boundary. Blood perfusion is included throughout plexus development and the emergent retinal architectures adapt and remodel in response to various biological factors. The resulting in silico RVP structures are compared with whole-mounted retinal vasculatures at various stages of development, and the agreement is found to be excellent. Having successfully benchmarked the model against wild-type data, the effect of transgenic over-expression of various genes is predicted, based on the ocular-specific expression of VEGF-A during murine development. These results can be used to help inform future experimental investigations of signalling pathways in ocular conditions characterised by aberrant angiogenesis.
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