Browsing by Author "Jansen, John A."

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    Autologously Generated Tissue-Engineered Bone Flaps for Reconstruction of Large Mandibular Defects in an Ovine Model
    (Mary Ann Liebert, Inc., 2015) Tatara, Alexander M.; Kretlow, James D.; Spicer, Patrick P.; Lu, Steven; Lam, Johnny; Liu, Wei; Cao, Yilin; Liu, Guangpeng; Jackson, John D.; Yoo, James J.; Atala, Anthony; van den Beucken, Jeroen J.J.P.; Jansen, John A.; Kasper, F. Kurtis; Ho, Tang; Demian, Nagi; Miller, Michael John; Wong, Mark E.; Mikos, Antonios G.
    The reconstruction of large craniofacial defects remains a significant clinical challenge. The complex geometry of facial bone and the lack of suitable donor tissue often hinders successful repair. One strategy to address both of these difficulties is the development of an in vivo bioreactor, where a tissue flap of suitable geometry can be orthotopically grown within the same patient requiring reconstruction. Our group has previously designed such an approach using tissue chambers filled with morcellized bone autograft as a scaffold to autologously generate tissue with a predefined geometry. However, this approach still required donor tissue for filling the tissue chamber. With the recent advances in biodegradable synthetic bone graft materials, it may be possible to minimize this donor tissue by replacing it with synthetic ceramic particles. In addition, these flaps have not previously been transferred to a mandibular defect. In this study, we demonstrate the feasibility of transferring an autologously generated tissue-engineered vascularized bone flap to a mandibular defect in an ovine model, using either morcellized autograft or synthetic bone graft as scaffold material.
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    Dual growth factor delivery from bilayered, biodegradable hydrogel composites for spatially-guided osteochondral tissue repair
    (Elsevier, 2014) Lu, Steven; Lam, Johnny; Trachtenberg, Jordan E.; Lee, Esther J.; Seyednejad, Hajar; van den Beucken, Jeroen J.J.P.; Tabata, Yasuhiko; Wong, Mark E.; Jansen, John A.; Mikos, Antonios G.; Kasper, F. Kurtis
    The present work investigated the use of biodegradable hydrogel composite scaffolds, based on the macromer oligo(poly(ethylene glycol) fumarate) (OPF), to deliver growth factors for the repair of osteochondral tissue in a rabbit model. In particular, bilayered OPF composites were used to mimic the structural layers of the osteochondral unit, and insulin-like growth factor-1 (IGF-1) and bone morphogenetic protein-2 (BMP-2) were loaded into gelatin microparticles and embedded within the OPF hydrogel matrix in a spatially controlled manner. Three different scaffold formulations were implanted in a medial femoral condyle osteochondral defect: 1) IGF-1 in the chondral layer, 2) BMP-2 in the subchondral layer, and 3) IGF-1 and BMP-2 in their respective separate layers. The quantity and quality of osteochondral repair was evaluated at 6 and 12 weeks with histological scoring and micro-computed tomography (micro-CT). While histological scoring results at 6 weeks showed no differences between experimental groups, micro-CT analysis revealed that the delivery of BMP-2 alone increased the number of bony trabecular islets formed, an indication of early bone formation, over that of IGF-1 delivery alone. At 12 weeks post-implantation, minimal differences were detected between the three groups for cartilage repair. However, the dual delivery of IGF-1 and BMP-2 had a higher proportion of subchondral bone repair, greater bone growth at the defect margins, and lower bone specific surface than the single delivery of IGF-1. These results suggest that the delivery of BMP-2 enhances subchondral bone formation and that, while the dual delivery of IGF-1 and BMP-2 in separate layers does not improve cartilage repair under the conditions studied, they may synergistically enhance the degree of subchondral bone formation. Overall, bilayered OPF hydrogel composites demonstrate potential as spatially-guided, multiple growth factor release vehicles for osteochondral tissue repair.
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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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    Evaluation of Bone Regeneration Using the Rat Critical Size Calvarial Defect
    (Nature Publishing Group, 2012-10) Spicer, Patrick P.; Kretlow, James D.; Young, Simon; Jansen, John A.; Kasper, F. Kurtis; Mikos, Antonios G.
    Animal models that are reliably reproducible, appropriate analogues to the clinical condition they are used to investigate, and that offer minimal morbidity and periprocedural mortality to the subject are the keystone to the preclinical development of translational technologies. For bone tissue engineering, a number of small animal models exist. Here we describe the protocol for one such model, the rat calvarial defect. This versatile model allows for evaluation of biomaterials and bone tissue engineering approaches within a reproducible, nonload-bearing orthotopic site. Critical steps to ensure appropriate experimental control and troubleshooting tips learned through extensive experience with this model are provided. The surgical procedure itself takes approximately 30 minutes to complete with approximately 2 hours of perioperative care, and tissue harvest is generally performed 4 to 12 weeks postoperatively. Several analytical techniques are presented, which evaluate the cellular and extracellular matrix components, functionality and mineralization, including histological, mechanical and radiographic methods.
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    Multimodal porogen platforms for calcium phosphate cement degradation
    (Wiley, 2019) Lodoso-Torrecilla, Irene; Grosfeld, Eline-Claire; Marra, Abe; Smith, Brandon T.; Mikos, Antonios G.; Ulrich, Dietmar JO; Jansen, John A.; van den Beucken, Jeroen JJP
    Calcium phosphate cements (CPCs) represent excellent bone substitute materials due to their biocompatibility and injectability. However, their poor degradability and lack of macroporosity limits bone regeneration. The addition of poly(d,l‐lactic‐co‐glycolic acid) (PLGA) particles improves macroporosity and therefore late stage material degradation. CPC degradation and hence, bone formation at an early stage remains challenging, due to the delayed onset of PLGA degradation (i.e., after 2–3 weeks). Consequently, we here explored multimodal porogen platforms based on sucrose porogens (for early pore formation) and PLGA porogens (for late pore formation) to enhance CPC degradation and analyzed mechanical properties, dynamic in vitro degradation and in vivo performance in a rat femoral bone defect model. Porogen addition to CPC showed to decrease compressive strength of all CPC formulations; transition of the crystal phase upon in vitro incubation increased compressive strength. Although dynamic in vitro degradation showed rapid sucrose dissolution within 1 week, no additional effects on CPC degradation or bone formation were observed upon in vivo implantation.
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    Osteochondral Tissue Regeneration using a Bilayered Composite Hydrogel with Modulating Dual Growth Factor Release Kinetics in a Rabbit Model
    (Elsevier, 2014) Kima, Kyobum; Lama, Johnny; Lua, Steven; Spicer, Patrick P.; Lueckgena, Aline; Yasuhiko, Tabata; Wong, Mark E.; Jansen, John A.; Mikos, Antonios G.; Kasper, F. Kurtis
    Biodegradable oligo(poly(ethylene glycol) fumarate) (OPF) composite hydrogels have been investigated for the delivery of growth factors (GFs) with the aid of gelatin microparticles (GMPs) and stem cell populations for osteochondral tissue regeneration. In this study, a bilayered OPF composite hydrogel that mimics the distinctive hierarchical structure of native osteochondral tissue was utilized to investigate the effect of transforming growth factor-β3 (TGF-β3) with varying release kinetics and/or insulin-like growth factor-1 (IGF-1) on osteochondral tissue regeneration in a rabbit full-thickness osteochondral defect model. The four groups investigated included (i) a blank control (no GFs), (ii) GMP-loaded IGF-1 alone, (iii) GMP-loaded IGF-1 and gel-loaded TGF-β3, and (iv) GMP-loaded IGF-1 and GMP-loaded TGF-β3 in OPF composite hydrogels. The results of an in vitro release study demonstrated that TGF-β3 release kinetics could be modulated by the GF incorporation method. At 12 weeks post-implantation, the quality of tissue repair in both chondral and subchondral layers was analyzed based on quantitative histological scoring. All groups incorporating GFs resulted in a significant improvement in cartilage morphology compared to the control. Single delivery of IGF-1 showed higher scores in subchondral bone morphology as well as chondrocyte and glycosaminoglycan amount in adjacent cartilage tissue when compared to a dual delivery of IGF-1 and TGF-β3, independent of the TGF-?3 release kinetics. The results suggest that although the dual delivery of TGF-β3 and IGF-1 may not synergistically enhance the quality of engineered tissue, the delivery of IGF-1 alone from bilayered composite hydrogels positively affects osteochondral tissue repair and holds promise for osteochondral tissue engineering applications.
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    Repair of complex ovine segmental mandibulectomy utilizing customized tissue engineered bony flaps
    (Public Library of Science, 2023) Watson, Emma; Pearce, Hannah A.; Hogan, Katie J.; Dijk, Natasja W.M. van; Smoak, Mollie M.; Barrios, Sergio; Smith, Brandon T.; Tatara, Alexander M.; Woernley, Timothy C.; Shum, Jonathan; Pearl, Craig B.; Melville, James C.; Ho, Tang; Hanna, Issa A.; Demian, Nagi; Beucken, Jeroen J.J.P. van den; Jansen, John A.; Wong, Mark E.; Mikos, Antonios G.
    Craniofacial defects require a treatment approach that provides both robust tissues to withstand the forces of mastication and high geometric fidelity that allows restoration of facial architecture. When the surrounding soft tissue is compromised either through lack of quantity (insufficient soft tissue to enclose a graft) or quality (insufficient vascularity or inducible cells), a vascularized construct is needed for reconstruction. Tissue engineering using customized 3D printed bioreactors enables the generation of mechanically robust, vascularized bony tissues of the desired geometry. While this approach has been shown to be effective when utilized for reconstruction of non-load bearing ovine angular defects and partial segmental defects, the two-stage approach to mandibular reconstruction requires testing in a large, load-bearing defect. In this study, 5 sheep underwent bioreactor implantation and the creation of a load-bearing mandibular defect. Two bioreactor geometries were tested: a larger complex bioreactor with a central groove, and a smaller rectangular bioreactor that were filled with a mix of xenograft and autograft (initial bone volume/total volume BV/TV of 31.8 ± 1.6%). At transfer, the tissues generated within large and small bioreactors were composed of a mix of lamellar and woven bone and had BV/TV of 55.3 ± 2.6% and 59.2 ± 6.3%, respectively. After transfer of the large bioreactors to the mandibular defect, the bioreactor tissues continued to remodel, reaching a final BV/TV of 64.5 ± 6.2%. Despite recalcitrant infections, viable osteoblasts were seen within the transferred tissues to the mandibular site at the end of the study, suggesting that a vascularized customized bony flap is a potentially effective reconstructive strategy when combined with an optimal stabilization strategy and local antibiotic delivery prior to development of a deep-seated infection.
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    Tunable calcium phosphate cement formulations for predictable local release of doxycycline
    (Elsevier, 2023) Liu, Qian; Lodoso-Torrecilla, Irene; Gunnewiek, Raquel Klein; Harhangi, Harry R.; Mikos, Antonios G.; van Niftrik, Laura; Jansen, John A.; Chen, Lili; Beucken, Jeroen J.J.P. van den
    Background Osteomyelitis is a bacterial infection, which leads to bone loss. Local treatment focuses on elimination of bacteria, which is preferable for simultaneous management of the bone defect after sequestrectomy and bone reconstruction in one-stage treatment of osteomyelitis. Calcium phosphate cements (CPCs) have attracted increased attention as bone substitute material because of their injectability and in situ self-setting properties, which allow for minimally invasive surgical procedures and local drug delivery. Methods We herein established a system to achieve different release profiles of the antibiotic drug doxycycline from CPC by finetuning their formulation. These CPC formulations were generated via facile addition of hydrolytically degrading PLGA particles, varying doses of doxycycline, and addition of the lubricant CMC. Results The CPC formulations exhibited appropriate handling properties in terms of injectability and setting time. Furthermore, doxycycline release profiles showed an adequate burst release followed by a cumulative release of up to 100% over a period of 8 weeks. Importantly, the released doxycycline retained its antibacterial activity against Staphylococcus aureus, the major pathogen causing osteomyelitis. Using an in vivo implantation model, antibacterial efficacy was demonstrated by a rapid decrease of inoculated S. aureus at the CPC surface and within surrounding tissues. Conclusions Our data show the versatility of the CPC system toward local antibacterial therapy, extending its application beyond bone substitution.