VEGF with AMD3100 Endogenously Mobilizes Mesenchymal Stem Cells and Improves Fracture Healing

A significant number of fractures develop non‐union. Mesenchymal stem cell (MSC) therapy may be beneficial, however, this requires cell acquisition, culture and delivery. Endogenous mobilization of stem cells offers a non‐invasive alternative. The hypothesis was administration of VEGF and the CXCR4 antagonist AMD3100 would increase the circulating pool of available MSCs and improve fracture healing. Ex‐breeder female wistar rats received VEGF followed by AMD3100, or sham PBS. Blood prepared for culture and colonies were counted. P3 cells were analyzed by flow cytometry, bi‐differentiation. The effect of mobilization on fracture healing was evaluated with 1.5 mm femoral osteotomy stabilized with an external fixator in 12–14 week old female Wistars. The mobilized group had significantly greater number of cfus/ml compared to controls, p = 0.029. The isolated cells expressed 1.8% CD34, 35% CD45, 61% CD29, 78% CD90, and differentiated into osteoblasts but not into adipocytes. The fracture gap in animals treated with VEGF and AMD3100 showed increased bone volume; 5.22 ± 1.7 µm3 and trabecular thickness 0.05 ± 0.01 µm compared with control animals (4.3 ± 3.1 µm3, 0.04 ± 0.01 µm, respectively). Radiographic scores quantifying fracture healing (RUST) showed that the animals in the mobilization group had a higher healing score compared to controls (9.6 vs. 7.7). Histologically, mobilization resulted in significantly lower group variability in bone formation (p = 0.032) and greater amounts of bone and less fibrous tissue than the control group. Clinical significance: This pre‐clinical study demonstrates a beneficial effect of endogenous MSC mobilization on fracture healing, which may have translation potential to prevent or treat clinical fractures at risk of delayed or non‐union fractures

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NASA GSFC Opportunities for STEM Professionals Using the Vantage Point of Space

NASA has a variety of learning opportunities for STEM professionals. Three opportunities at GSFC are examined in this chapter: 1) standard summer research and development internship for undergraduates, 2) senior internship for undergraduate and graduate students and 3) a workshop series for informal learning center professionals. We describe these programs, examine their evolution with respect to most effective education practices and their assessment and evaluation, and identify the similarities and differences between them. The internship programs highlight authentic project-based research and development experiences with the senior internship providing a richer, deeper, and more demanding experience that has greater professional value. The workshops for informal learning center professionals on-the-other hand, focus on building knowledge of GSFC s science and engineering strengths among these professionals, and on building enduring partnerships between individuals (participants and GSFC scientist, engineers and educators) and between organizations (GSFC and the informal learning center). Finally, we examine the characteristics of these programs from a design and management perspective. Through this examination we identify a general structure that provides insight into more effective design and management of similar education programs

Postoperative complications associated with external skeletal fixators in cats

OBJECTIVES: The objective of this study was to quantify complications associated with external skeletal fixators (ESFs) in cats and to identify potential risk factors. METHODS: A retrospective review of medical records and radiographs following ESF placement was performed. RESULTS: Case records of 140 cats were reviewed; fixator-associated complications (FACs) occurred in 19% of cats. The region of ESF placement was significantly associated with complication development. Complications developed most frequently in the femur (50%), tarsus (35%) and radius/ulna (33%). Superficial pin tract infection (SPTI) and implant failure accounted for 45% and 41% of all FACs, respectively. SPTI occurred more frequently in the femur, humerus and tibia, with implant failure more frequent in the tarsus. No association between breed, age, sex, weight, fracture type (open vs closed), ESF classification, number of pins per bone segment, degree of fracture load sharing, and the incidence or type of FAC was identified. No association between region of placement, breed, age, sex, weight, fracture type (open vs closed), ESF classification, number of pins per bone segment, fracture load sharing and the time to complication development was identified. CONCLUSIONS AND RELEVANCE: Complication development is not uncommon in cats following ESF placement. The higher complication rate in the femur, tarsus and radius/ulna should be considered when reviewing options for fracture management. However, cats appear to have a lower rate of pin tract infections than dogs

Postoperative Complications Associated with External Skeletal Fixators in Dogs

OBJECTIVES:  To quantify and evaluate risks of complications attributable to external skeletal fixator (ESF) usage in dogs. METHODS:  A retrospective review of medical records following ESF placement. RESULTS:  Case records of 97 dogs were reviewed; fixator-associated complications occurred in 79/97 dogs. Region of ESF placement was significantly associated with complication development (p = 0.005), not complication type (p = 0.086). Complications developed most frequently in the tarsus (9/10), manus (8/9) and humerus (8/9). Superficial pin-tract infection and implant failure occurred in 38/97 and 17/97 dogs, respectively. Superficial pin-tract infection occurred frequently in the femur, humerus, radius and ulna and the pes, with implant failure frequent in the tarsus and deep pin-tract infection in the manus and tibia. Transarticular frames were significantly more likely to develop a complication (p = 0.028). Age was significantly associated with complication development (p = 0.029). No associations between breed, sex, weight, fracture type (open or closed), ESF classification and the incidence or type of complications were identified. No associations between, breed, age, sex, weight, fracture type (open or closed), ESF classification and the time to complication development were identified. CLINICAL SIGNIFICANCE:  Fixator-associated complications are common in dogs, with the majority of complications related to implant infection. Region and placement of transarticular frames should be carefully considered when selecting stabilization method