Browsing by Author "Kinard, Lucas A."

Now showing 1 - 6 of 6
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    Articular chondrocytes and mesenchymal stem cells seeded on biodegradable scaffolds for the repair of cartilage in a rat osteochondral defect model
    (Elsevier, 2014) Dahlin, Rebecca L.; Kinard, Lucas A.; Lam, Johnny; Needham, Clark J.; Lu, Steven; Kasper, F. Kurtis; Mikos, Antonios G.
    This work investigated the ability of co-cultures of articular chondrocytes and mesenchymal stem cells (MSCs) to repair articular cartilage in osteochondral defects. Bovine articular chondrocytes and rat MSCs were seeded in isolation or in co-culture onto electrospun poly(ɛ-caprolactone) (PCL) scaffolds and implanted into an osteochondral defect in the trochlear groove of 12-week old Lewis rats. Additionally, a blank PCL scaffold and untreated defect were investigated. After 12 weeks, the extent of cartilage repair was analyzed through histological analysis, and the extent of bone healing was assessed by quantifying the total volume of mineralized bone in the defect through microcomputed tomography. Histological analysis revealed that the articular chondrocytes and co-cultures led to repair tissue that consisted of more hyaline-like cartilage tissue that was thicker and possessed more intense Safranin O staining. The MSC, blank PCL scaffold, and empty treatment groups generally led to the formation of fibrocartilage repair tissue. Microcomputed tomography revealed that while there was an equivalent amount of mineralized bone formation in the MSC, blank PCL, and empty treatment groups, the defects treated with chondrocytes or co-cultures had negligible mineralized bone formation. Overall, even with a reduced number of chondrocytes, co-cultures led to an equal level of cartilage repair compared to the chondrocyte samples, thus demonstrating the potential for the use of co-cultures of articular chondrocytes and MSCs for the in vivo repair of cartilage defects.
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    Evaluation of antibiotic releasing porous polymethylmethacrylate space maintainers in an infected composite tissue defect model
    (Elsevier, 2013-11) Spicer, Patrick P.; Shah, Sarita R.; Henslee, Allan M.; Watson, Brendan M.; Kinard, Lucas A.; Kretlow, James D.; Bevil, Kristin; Kattchee, Lauren; Bennett, George N.; Demian, Nagi M.; Mende, Katrin; Murray, Clinton K.; Jansen, John A.; Wong, Mark E.; Mikos, Antonios G.; Kasper, F.Kurtis
    This study evaluated the in vitro and in vivo performance of antibiotic-releasing porous polymethylmethacrylate (PMMA)-based space maintainers comprising a gelatin hydrogel porogen and a poly(DL-lactic-co-glycolic acid) (PLGA) particulate carrier for antibiotic delivery. Colistin was released in vitro from either gelatin or PLGA microparticle loaded PMMA constructs, with gelatin-loaded constructs releasing colistin over approximately 7 days and PLGA microparticle-loaded constructs releasing colistin up to 8 weeks. Three formulations with either a burst release or extended release in different doses were tested in a rabbit mandibular defect inoculated with Acinetobacter baumannii (2 × 107 colony forming units/mL). In addition, one material control that released antibiotic but was not inoculated with A. baumannii was tested. A. baumannii was not detectable in any animal after 12 weeks by culture of the defect, saliva, or blood. Defects with high-dose, extended-release implants had greater soft tissue healing compared to defects with burst release implants, with 8 out of 10 animals showing healed mucosae compared to 2 out of 10 with healed mucosae, respectively. Extended release of locally delivered colistin via a PLGA microparticle carrier improved soft tissue healing over the implants compared to burst release of colistin from a gelatin carrier.
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    Osteochondral tissue regeneration through polymeric delivery of DNA encoding for the SOX trio and RUNX2
    (Elsevier, 2014) Needham, Clark J.; Shah, Sarita R.; Dahlin, Rebecca L.; Kinard, Lucas A.; Lam, Johnny; Watson, Brendan M.; Lu, Steven; Kasper, F. Kurtis; Mikos, Antonios G.
    Native osteochondral repair is often inadequate owing to the inherent properties of the tissue, and current clinical repair strategies can result in healing with a limited lifespan and donor site morbidity. This work investigates the use of polymeric gene therapy to address this problem by delivering DNA encoding for transcription factors complexed with the branched poly(ethylenimine)–hyaluronic acid (bPEI–HA) delivery vector via a porous oligo[poly(ethylene glycol) fumarate] hydrogel scaffold. To evaluate the potential of this approach, a bilayered scaffold mimicking native osteochondral tissue organization was loaded with DNA/bPEI–HA complexes. Next, bilayered implants either unloaded or loaded in a spatial fashion with bPEI–HA and DNA encoding for either Runt-related transcription factor 2 (RUNX2) or SRY (sex determining region Y)-box 5, 6, and 9 (the SOX trio), to generate bone and cartilage tissues respectively, were fabricated and implanted in a rat osteochondral defect. At 6 weeks post-implantation, micro-computed tomography analysis and histological scoring were performed on the explants to evaluate the quality and quantity of tissue repair in each group. The incorporation of DNA encoding for RUNX2 in the bone layer of these scaffolds significantly increased bone growth. Additionally, a spatially loaded combination of RUNX2 and SOX trio DNA loading significantly improved healing relative to empty hydrogels or either factor alone. Finally, the results of this study suggest that subchondral bone formation is necessary for correct cartilage healing.
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    Synthesis of oligo(poly(ethylene glycol) fumarate)
    (Nature Publishing Group, 2012) Kinard, Lucas A.; Kasper, F. Kurtis; Mikos, Antonios G.
    This protocol describes the synthesis of oligo(poly(ethylene glycol) fumarate) (OPF) (1-35 kDa)(a polymer useful for tissue engineering applications) by a one-pot reaction of poly(ethylene glycol) (PEG) and fumaryl chloride. The procedure involves three parts: dichloromethane and PEG are first dried; the reaction step follows in which fumaryl chloride and triethylamine are added dropwise to a solution of PEG in dichloromethane; and finally the product solution is filtered to remove byproduct salt, and the OPF product is twice crystallized, washed, and dried under vacuum. The reaction is affected by PEG molecular weight and reactant molar ratio. The OPF product is cross-linked by radical polymerization by either a thermally induced or UV-induced radical initiator, and the physical properties of the OPF oligomer and resulting cross-linked hydrogel are easily tailored by varying PEG molecular weight. OPF hydrogels are injectable, polymerize in situ, and undergo biodegradation by hydrolysis of ester bonds. The expected time required to complete this protocol is 6 d.
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    Synthetic biodegradable hydrogel delivery of demineralized bone matrix for bone augmentation in a rat model
    (Elsevier, 2014) Kinard, Lucas A.; Dahlin, Rebecca L.; Lam, Johnny; Lu, Steven; Lee, Esther J.; Kasper, F. Kurtis; Mikos, Antonios G.
    There exists a strong clinical need for a more capable and robust method to achieve bone augmentation, and a system with fine-tuned delivery of demineralized bone matrix (DBM) has the potential to meet that need. As such, the objective of the present study was to investigate a synthetic biodegradable hydrogel for the delivery of DBM for bone augmentation in a rat model. Oligo(poly(ethylene glycol) fumarate) (OPF) constructs were designed and fabricated by varying the content of rat-derived DBM particles (either 1:3, 1:1 or 3:1 DBM:OPF weight ratio on a dry basis) and using two DBM particle size ranges (50–150 or 150–250 μm). The physical properties of the constructs and the bioactivity of the DBM were evaluated. Selected formulations (1:1 and 3:1 with 50–150 μm DBM) were evaluated in vivo compared to an empty control to investigate the effect of DBM dose and construct properties on bone augmentation. Overall, 3:1 constructs with higher DBM content achieved the greatest volume of bone augmentation, exceeding 1:1 constructs and empty implants by 3- and 5-fold, respectively. As such, we have established that a synthetic, biodegradable hydrogel can function as a carrier for DBM, and that the volume of bone augmentation achieved by the constructs correlates directly to the DBM dose.
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    Synthetic Hydrogel Delivery of Growth Factors and Demineralized Bone Matrix for Bone Augmentation
    (2014-04-24) Kinard, Lucas A.; Mikos, Antonios G.; Kasper, Kurt; Zygourakis, Kyriacos; Farach-Carson, Cindy
    The overarching objective of this thesis was to investigate synthetic hydrogel delivery of growth factors and demineralized bone matrix (DBM) for bone augmentation. Our motivation rests on observed weaknesses of current clinical approaches to bone augmentation, which synthetic hydrogels hope to overcome based on non-invasive application, contouring, tunability, and drug delivery. First, we investigated the release of bone morphogenetic protein-2 (BMP-2) from gelatin microparticles. Hydrogel composites based on oligo(poly(ethylene glycol) fumarate) (OPF) were prepared to investigate the effect of gelatin amount, gelatin type, and BMP-2 loading phase on release. The most significant factor affecting the release of BMP-2 was the loading phase, whereby gelatin loading reduced the burst release and increased BMP-2 release during later phases. Our results indicated tunability of the physical properties and BMP-2 release kinetics of our hydrogel composites. Second, we developed a rat model for bone augmentation and investigated our BMP-2 delivery system in vivo. Our animal model achieved rigid immobilization of bilateral implants apposed to the parietal bone of the rat. The BMP-2 release profile was varied and compared to the implantation of a material control without BMP-2. The volume of bone augmentation did not vary between groups after 4 weeks largely due to insignificant hydrogel degradation. Altogether, a promising rat model of bone augmentation was established; however, refinement of the hydrogel composites was suggested. Lastly, we investigated OPF for the delivery of DBM for bone augmentation in a rat model. OPF constructs were designed and fabricated by varying the content of rat-derived DBM particles and using two DBM particle size ranges. The physical properties of the constructs and the bioactivity of the DBM were evaluated. Select formulations were evaluated in vivo compared to an empty control to investigate the effect of DBM dose and construct properties on bone augmentation. Overall, constructs with higher DBM content achieved the greatest volume of bone augmentation, exceeding lower DBM constructs and empty implants by 3-fold and 5-fold, respectively. We established that a synthetic, biodegradable hydrogel can function as a carrier for DBM, and that the volume of bone augmentation achieved by the constructs correlated directly to DBM dose.