Background: We evaluated geographic patterns for immediate and delayed breast reconstruction (IBR, DBR) in Ontario. The influence of plastic surgeon availability on rates and service provision was determined. Methods: We examined IBR and DBR from 2002 through 2011 across Ontario counties. Regional availability of plastic surgeons was described. Geographic patterns were examined using funnel plots, random-effects models and migration indices. Results: Over ½ Ontario counties have no plastic surgeons. IBR ranged from 0 to 21.5% across counties and differences in plastic surgeon availability explained 41% of variation (p < 0.0001). For DBR there was less variation. 5/45 counties performed ¾ of BR, however rates among local residents were not highest. Interpretation: Nearly 1/3 of the population has limited access to plastic surgeons, contributing to low rates of BR. Geographic access is a major determinant of IBR but is less important for DBR, however service provision for both was highly regionalized.

Subglottic stenosis, malignancy and traumatic injury to the trachea require surgical resection. When defects are less than 50% of the tracheal length in adults and 1/3 in children, a circumferential resection and primary anastomosis affords excellent results. For longer lesions, on the other hand, there are no currently acceptable solutions leading to patients requiring permanent tracheostomies or palliative treatment. Tracheal replacement approaches with synthetic prosthesis and scaffolds have all led to inflammation, obstruction, mucous build-up and eventual restenosis. Tissue-engineering approaches using recipients’ own stem cells and biologic scaffolds derived from decellularized donor trachea have shown great promise. They have the potential to abrogate the need for immunosuppressive therapy. Our research focuses on three major limitations in this field including the structural integrity, the immunogenicity and the recellularization of donor tracheae. We compared three decellularization protocols, quantified and qualified the extracellular matrix (ECM) components and performed compliance measurements on large circumferential tracheal scaffolds following cyclical decellularization techniques and illustrated significant differences in ECM composition and resultant structural integrity of decellularized tracheal scaffolds depending on the protocol. In addition, we investigated the immunogenicity of decellularized and recellularized tracheal allografts at a protein level and in vitro and in vivo T cell proliferation. Decellularization is associated with a delay in leukocyte infiltration and recellularization promoted cartilage preservation and the recruitment of regulatory T cells. We described a dramatic increase of TGF-β1 in recellularized scaffolds. Moreover, we designed a dual-chamber bioreactor for recellularization of tracheal allografts. Our method allowed for dynamic perfusion seeding, confirmed adherence of two different cell types and achieved higher cell numbers and homogeneous structures compared to traditional static seeding methods. In summary, we have identified and addressed three major limitations for tissue-engineering of long-segment decellularized tracheal scaffolds relating to structural integrity, immunogenicity and recellularization techniques.

Psoriatic Arthritis (PsA) is an inflammatory arthritis associated with psoriasis that leads to progressive joint damage. Genetic variants in the Major Histocompatibility Complex (MHC) region on human chromosome 6p, especially Human Leucocyte Antigen (HLA), are the most important genetic risk variants associated with susceptibility to PsA. I aimed to investigate the heritability of PsA and to determine the association between HLA polymorphisms with susceptibility and severity of PsA. I first validated the new CASPAR classification criteria for PsA in patients in with both early and established disease. Subsequently, I demonstrated that PsA as defined by the CASPAR criteria has a high recurrence risk ratio. In a large case-control and family-based association study, I demonstrated that the class I HLA alleles, HLA-C*12/B*38, -B*27 and -C*06/B*57 are associated with increased susceptibility to PsA. HLA class I molecules biologically interact with Killer-cell Immunoglobulin-like Receptors (KIR) on Natural Killer (NK) to influence immune response. I demonstrated that KIR2DS2 and HLA C group 2 and HLA-B Bw4 were associated with PsA susceptibility. Further analyses of PsA cases with Type II psoriasis and with dactylitis suggested that HLA-C*02, -B*27, -B*38 and KIR2DS2 may be markers of musculoskeletal manifestations of PsA. Furthermore, using longitudinal data, I demonstrated that HLA-B*39, -B*27, -A*02 and KIR3DS1 are associated with peripheral joint damage progression whereas the alleles –DQB1*0604, -C*04 and –B*60 are associated with less damage progression. HLA-C*02, -C*12, -DQB1*0609 and KIR2DS1 are associated with higher risk of sacroiliitis, and HLA-B*27 with syndesmophytes. HLA-A*29 was associated with reduced risk of development of both sacroiliitis and syndesmophytes. These studies indicate that HLA alleles and KIR genes are important in PsA susceptibility and severity and suggest that CD8+ T cells and NK cells that modulate the innate and adaptive immune response play an important role in the susceptibility and severity of PsA.

Subglottic stenosis, malignancy and traumatic injury to the trachea require surgical resection. When defects are less than 50% of the tracheal length in adults and 1/3 in children, a circumferential resection and primary anastomosis affords excellent results. For longer lesions, on the other hand, there are no currently acceptable solutions leading to patients requiring permanent tracheostomies or palliative treatment. Tracheal replacement approaches with synthetic prosthesis and scaffolds have all led to inflammation, obstruction, mucous build-up and eventual restenosis. Tissue-engineering approaches using recipients’ own stem cells and biologic scaffolds derived from decellularized donor trachea have shown great promise. They have the potential to abrogate the need for immunosuppressive therapy. Our research focuses on three major limitations in this field including the structural integrity, the immunogenicity and the recellularization of donor tracheae. We compared three decellularization protocols, quantified and qualified the extracellular matrix (ECM) components and performed compliance measurements on large circumferential tracheal scaffolds following cyclical decellularization techniques and illustrated significant differences in ECM composition and resultant structural integrity of decellularized tracheal scaffolds depending on the protocol. In addition, we investigated the immunogenicity of decellularized and recellularized tracheal allografts at a protein level and in vitro and in vivo T cell proliferation. Decellularization is associated with a delay in leukocyte infiltration and recellularization promoted cartilage preservation and the recruitment of regulatory T cells. We described a dramatic increase of TGF-β1 in recellularized scaffolds. Moreover, we designed a dual-chamber bioreactor for recellularization of tracheal allografts. Our method allowed for dynamic perfusion seeding, confirmed adherence of two different cell types and achieved higher cell numbers and homogeneous structures compared to traditional static seeding methods. In summary, we have identified and addressed three major limitations for tissue-engineering of long-segment decellularized tracheal scaffolds relating to structural integrity, immunogenicity and recellularization techniques.

Familial Pancreatic Cancer (FPC) is an autosomal dominant condition with greater then 80% of genetic causes unknown. We hypothesize that an integrative approach employing germline exome sequencing and somatic microarray analysis of FFPE DNA will identify novel tumour suppressor genes (TSGs). 55 FPC and 21 sporadic PDAC tumours were analyzed on the Affymetrix Oncoscan FFPE Express 2.0 SNP microarray and compared to data from 33 germline FPC cases analyzed on the Illumina GAIIx Analyzer. We have demonstrated that FPC is genetically heterogeneous with recurrent loss at CDKN2A/p16, TP53 and SMAD4. Analysis of 2 sisters has shown a shared loss region involving DCLK3 and SERPINF1. By an integrative approach, we have identified ATPAF1-AS1 and MAP3K6 as potential TSGs. Germline variants of these genes have been confirmed by Sanger sequencing and somatic fluorescence in-situ hybridization. Future functional studies will better characterize the importance of these regions and novel putative TSGs in FPC.

Familial Pancreatic Cancer (FPC) is an autosomal dominant condition with greater then 80% of genetic causes unknown. We hypothesize that an integrative approach employing germline exome sequencing and somatic microarray analysis of FFPE DNA will identify novel tumour suppressor genes (TSGs). 55 FPC and 21 sporadic PDAC tumours were analyzed on the Affymetrix Oncoscan FFPE Express 2.0 SNP microarray and compared to data from 33 germline FPC cases analyzed on the Illumina GAIIx Analyzer. We have demonstrated that FPC is genetically heterogeneous with recurrent loss at CDKN2A/p16, TP53 and SMAD4. Analysis of 2 sisters has shown a shared loss region involving DCLK3 and SERPINF1. By an integrative approach, we have identified ATPAF1-AS1 and MAP3K6 as potential TSGs. Germline variants of these genes have been confirmed by Sanger sequencing and somatic fluorescence in-situ hybridization. Future functional studies will better characterize the importance of these regions and novel putative TSGs in FPC.

Background: We evaluated geographic patterns for immediate and delayed breast reconstruction (IBR, DBR) in Ontario. The influence of plastic surgeon availability on rates and service provision was determined. Methods: We examined IBR and DBR from 2002 through 2011 across Ontario counties. Regional availability of plastic surgeons was described. Geographic patterns were examined using funnel plots, random-effects models and migration indices. Results: Over ½ Ontario counties have no plastic surgeons. IBR ranged from 0 to 21.5% across counties and differences in plastic surgeon availability explained 41% of variation (p < 0.0001). For DBR there was less variation. 5/45 counties performed ¾ of BR, however rates among local residents were not highest. Interpretation: Nearly 1/3 of the population has limited access to plastic surgeons, contributing to low rates of BR. Geographic access is a major determinant of IBR but is less important for DBR, however service provision for both was highly regionalized.

Due to its significant morbidity, alternatives to autogenous bone grafting are required. Recent research has focused on application of growth factors, including bone morphogenetic proteins (BMPs). Two recombinant human BMP (rhBMP) containing bioimplants, Infuse® (rhBMP-2) and OP-1® (rhBMP-7), are approved for human application. Objective: to provide a direct comparison of the two approved rhBMP containing bioimplants in their clinically available forms. Methods: Activity of rhBMP-2 and -7 were tested using the C2C12 cell based assay comparing alkaline phosphatase (ALP) activity. Activity of Infuse® or OP-1® bioimplants containing 52.5µg of rhBMP-2 or rhBMP-7 were compared using a mouse muscle pouch assay and analyzed with micro CT (mCT) and histology. Results: in vitro: rhBMP-2 induced greater ALP production than rhBMP-7 at different time points. In vivo: OP-1® induced greater bone volume than Infuse® of equivalent quality based on mCT. Conclusions: In the clinically available form, OP-1® induced greater bone volume than Infuse®.

Bisphosphonate-related osteonecrosis of the jaws (BRONJ) occurs subsequent to intravenous and oral bisphosphonate exposure in a small subset of patients. Evidence of concurrent bacterial colonization at sites of bone necrosis, previous reports of neutrophil-related complications in some patients taking bisphosphonates along with perturbed neutrophil function in bisphosphonate-treated mice suggests an innate immune role in the development of bisphosphonate-related osteonecrosis of the jaws. This study investigates neutrophil function in BRONJ patients to determine if neutrophil functional defects may serve as a potential biomarker for BRONJ susceptibility. Patients with BRONJ and patients beginning intravenous pamidronate were studied. Eighteen patients with BRONJ and five patients beginning pamidronate therapy provided oral and blood neutrophil samples. Neutrophils from the population of patients with bisphosphonate-related osteonecrosis of the jaws and from those post-pamidronate treatment showed lower reactive-oxygen species production. These data suggest that a compromise in neutrophil function may be a potential biomarker for BRONJ susceptibility.

Spontaneous subarachnoid hemorrhage (SAH) is a form of hemorrhagic stroke that accounts for approximately 7% of all strokes worldwide. Recently, researchers have gained insight into some possible genetic influences involved in the response to SAH. The goal of this study was to investigate the potential contribution of different mouse genetic backgrounds to brain injury after SAH. SAH was induced in 7 inbred strains of mice, and the degree of large artery vasospasm and brain injury was assessed. After 48 hours, SAH mice showed a significant reduction in middle cerebral artery diameter and increased neuronal injury in the cerebral cortex compared to sham controls. The degree of vasospasm and brain injury varied across strains. This data suggests that vasospasm and neuronal injury may not correlate, and that different genetic factors may influence each one. Future investigations may provide invaluable insight into the causes of these inter-strain differences and potential genetic contributors.