Development of an In-Vitro Tissue Engineered Blood Vessel Mimic Using Human Large Vessel Cell Sources

Tissue engineering is an emerging field that offers novel and unmatched potential medical therapies and treatments. While the vast aim of tissue engineering endeavors is to provide clinically implantable constructs, secondary applications have been developed to utilize tissue-engineered constructs for in-vitro evaluation of devices and therapies. Specifically, in-vitro blood vessel mimics (BVM) have been developed to create a bench-top blood vessel model using human cells that can be used to test and evaluate vascular disease treatments and intravascular devices. Previous BVM work has used fat derived human microvascular endothelial cells (EC) sodded on an ePTFE scaffold. To create a more physiologically accurate model, a dual layer of large vessel endothelial and smooth muscle cells (SMC) on an ePTFE tube is investigated throughout this thesis. Human umbilical vein endothelial cells (HUVEC) and human umbilical vein smooth muscle cells (HUVSMC) were chosen as the large vessel cell types and cultivated according to standard procedures. Before dual sodding, sodding density experiments with HUVSMC were performed to determine the number of cells required to create a confluent cell layer. HUVSMC sodded by trans-luminal pressure at densities ranging from 3.5x10^5 cells/cm^2 to 1.0x10^6 cells/cm^2 were run for one day to observe luminal coverage. After determining the desirable range for HUVSMC sodding, HUVSMC experiments with 5.0x10^5 cells/cm^2 and 7.5x10^5 cells/cm^2 were run over seven days to evaluate progression of the graft over time. Histology and SEM methods were used for analysis. A HUVEC study was next conducted over 7 days to confirm that the large vessel endothelial cell could be sodded and sustained on ePTFE in-vitro. Next, dual sodding was performed by pressure sodding HUVSMC at 7.5x10^5 cells/cm^2 followed by trans-luminal flow for 30 minutes. HUVECs were subsequently trans-luminally pressure sodded at 5.0x10^5 cells/cm^2 followed by an additional 30 minutes of trans-luminal flow; perfusion flow began following the final 30 minutes of trans-luminal flow. Experiments for the dual layered grafts were run for both one and seven days to evaluate and develop the dual sodding protocol as well as observe the co-culture over time. Analysis of the dual layered grafts was performed by SEM, histology, and fluorescence microscopy. HUVECs were incubated with Cell Tracker™ prior to dual sodding and both cell types with bisbenzimide after graft harvest to attempt to distinguish between cell types. Results from the thesis illustrate that large vessel smooth muscle and endothelial cells can be sodded onto ePTFE scaffolds and sustained within the in-vitro BVM system for up to 7 days. Furthermore, cost analysis demonstrates that the addition of a smooth muscle cell layer adds minimal costs to the BVM system. In conclusion, the studies contained within this thesis culminate in a protocol for the dual sodding of smooth muscle and endothelial cells with the aim of creating a physiologically representative co-culture blood vessel mimic

A Rare Case of an Irreducible Patella Dislocation

Reports of irreducible patellar dislocations are exceedingly sparse throughout the literature. Obvious radiographic or physical exam findings including fracture or inversion of the patella are often present to explain the block to reduction. Not described previously in the literature is the instance of an irreducible patella dislocation in the setting of innocuous appearing injury imaging. We present a case of a healthy thirty-two-year-old female who sustained an irreducible lateral patella dislocation while participating in a dance aerobics class. Closed means of reduction were unsuccessful, necessitating open reduction. Intraoperative findings suggest incarceration of a nondisplaced fracture and a chondral defect as the block to reduction. Following open reduction, the patient has had no further episodes of pain or instability related to the patella at one-year follow-up. Irreducible patellar dislocations are exceedingly rare injuries, where associated osseous or chondral lesions may necessitate open reduction despite innocuous appearing initial imaging. A high index of suspicion to proceed with open reduction may limit repeated attempts at closed reduction and further injury

High Percentage of Complications and Re-Operations Following Dynamic Locking Plate Fixation with the Targon® FN for Intracapsular Proximal Femoral Fractures: An Analysis of Risk Factors

The ideal surgical treatment of femoral neck fractures remains controversial. When treating these fractures with internal fixation, many fixation constructs exist. The primary aim of this study was to evaluate the incidence and specific risk factors associated with complication and re-operation following fixation of intracapsular proximal femoral fractures using the Targon-FN system (B.Braun Melsungen AG). A secondary aim was to identify if lateral prominence of the implant relative to the lateral border of the vastus ridge was a specific risk factor for elective plate removal. Methodically, a retrospective case series was conducted of all consecutive adult patients treated at a single level 1 trauma center in Switzerland for an intracapsular proximal femoral fracture with the Targon-FN. Demographic data were collected. Patients with a follow-up of less than three months were excluded. Complications as well as plate position were recorded. Statistical analysis to identify specific risk factors for re-operation and complications was performed. In result, a total of 72 cases with intracapsular femoral neck fractures were treated with the Targon-FN locking plate system between 2010 and 2017. Thirty-four patients (47.2%) experienced one or more complications. The most common complication was mechanical irritation of the iliotibial band (ITB) (23.6%, n = 17). Complications included intraarticular screw perforation (6.9%, n = 5), avascular necrosis (5.6%, n = 4), non-union (5.6%, n = 4) among others. In total, 46 re-operations were required. Younger age, fracture displacement and time to postoperative weight bearing were identified as risk factors for re-operation. In conclusion, intracapsular femoral neck fractures treated with the Targon-FN system resulted in a high rate of post-operative complication and re-operation. Statistical analysis revealed patient age, fracture displacement, time to postoperative full weight bearing were risk factors for re-operation. The main limitation is the limited number of cases and a short follow-up of less than 12 months in a subgroup of our patients