Reduction of ectopic bone growth in critically-sized rat mandible defects by delivery of rhBMP-2 from kerateine biomaterials

Kowalczewski, Christine; Tombyln, Seth; Wasnick, David C.; Hughes, Michael; Ellenburg, Mary D.; Callahan, Michael F.; Smith, Thomas L.; Dyke, Mark Van; Burnett, Luke; Saul, Justin M.

doi:10.1016/j.biomaterials.2013.12.087

Cited by 52 publications

(51 citation statements)

References 30 publications

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“…It has previously been observed that release of rhBMP-2 from keratin hydrogels correlates with the rate of gel erosion [22, 23], suggesting a possible interaction between rhBMP-2 and keratin. Here, we determined an equilibrium binding value by a solid phase assay for rhBMP-2 and rhIGF-1 in order to (1) evaluate the strength of the interaction and (2) to determine if alkylation led to a change in the interaction.…”

Section: Resultsmentioning

confidence: 99%

“…Similarly, given the effects of keratin in burn wound healing [14], co-delivery of antibiotics may aid in reducing bacterial colonization to provide improved treatment and healing profiles [63]. As noted above, the higher binding affinity of rhBMP-2 for keratin may be advantageous compared to collagen in reducing ectopic bone growth, as we have recently reported [23]. Further, the ability to modulate keratin biomaterials that promote strong cell attachment while providing temporal control over delivery of therapeutic agents may lend keratin to other TERM applications that require more than a material alone.…”

Section: Discussionmentioning

confidence: 96%

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Alkylation of human hair keratin for tunable hydrogel erosion and drug delivery in tissue engineering applications

et al. 2015

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Polymeric biomaterials that provide a matrix for cell attachment and proliferation while achieving delivery of therapeutic agents are an important component of tissue engineering and regenerative medicine strategies. Keratins are a class of proteins that have received attention for numerous tissue engineering applications because, like other natural polymers, they promote favorable cell interactions and have non-toxic degradation products. Keratins can be extracted from various sources including human hair, and they are characterized by a high percentage of cysteine residues. Thiol groups on reductively extracted keratin (kerateine) form disulfide bonds, providing a more stable cross-linked hydrogel network than oxidatively extracted keratin (keratose) that cannot form disulfide crosslinks. We hypothesized that an iodoacetamide alkylation (or “capping”) of cysteine thiol groups on the kerateine form of keratin could be used as a simple method to modulate the levels of disulfide crosslinking in keratin hydrogels, providing tunable rates of gel erosion and therapeutic agent release. After alkylation, the alkylated kerateines still formed hydrogels and the alkylation led to changes in the mechanical and visco-elastic properties of the materials consistent with loss of disulfide crosslinking. The alkylated kerateines did not lead to toxicity in MC3T3-E1 pre-osteoblasts. These cells adhered to keratin at levels comparable to fibronectin and greater than collagen. Alkylated kerateine gels eroded more rapidly than non-alkylated kerateine and this control over erosion led to tunable rates of delivery of rhBMP-2, rhIGF-1, and ciprofloxacin. These results demonstrate that alkylation of kerateine cysteine residues provides a cell-compatible approach to tune rates of hydrogel erosion and therapeutic agent release within the context of a naturally-derived polymeric system.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 96%

Alkylation of human hair keratin for tunable hydrogel erosion and drug delivery in tissue engineering applications

et al. 2015

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“…Unlike collagen and some other naturally-derived proteins, to our knowledge humans do not produce enzymes that specifically degrade keratins (i.e., keratinases), which allows these materials to persist in vivo for longer periods of time. Lastly, in terms of controlled release, we have previously suggested 35,36 that release of therapeutic agents from keratin biomaterials is related to adsorption affinity of these materials to keratin and therefore release is not simply diffusion-mediated.…”

Section: Introductionmentioning

confidence: 99%

Keratin hydrogel carrier system for simultaneous delivery of exogenous growth factors and muscle progenitor cells

et al. 2015

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Ideal material characteristics for tissue engineering or regenerative medicine approaches to volumetric muscle loss (VML) include the ability to deliver cells, growth factors and molecules that support tissue formation from a system with a tunable degradation profile. Two different types of human hair-derived keratins were tested as options to fulfill these VML design requirements: (1) oxidatively extracted keratin (keratose) characterized by a lack of covalent crosslinking between cysteine residues, and (2) reductively extracted keratin (kerateine) characterized by disulfide crosslinks. Human skeletal muscle myoblasts cultured on coatings of both types of keratin had increased numbers of multinucleated cells compared to collagen or Matrigel™ and adhesion levels greater than collagen. Rheology showed elastic moduli from 102 – 105 Pa and viscous moduli from 101 – 104 Pa depending on gel concentration and keratin type. Kerateine and keratose showed differing rates of degradation due to the presence or absence of disulfide crosslinks, which likely contributed to observed differences in release profiles of several growth factors. In vivo testing in a subcutaneous mouse model showed that keratose hydrogels can be used to deliver mouse muscle progenitor cells and growth factors. Histological assessment showed minimal inflammatory responses and an increase in markers of muscle formation.

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“…The current clinical strategy that uses supraphysiological doses of rhBMP-2 in the device helps to overcome the therapeutic threshold set by BMP-2 antagonists and inhibitors. Previous studies have focused on lowering loading concentrations by using alternative biomaterials to control the rate BMP-2 release from the carrier system [12, 18, 19, 51]. …”

Section: Discussionmentioning

confidence: 99%

“…This negative feedback mechanism provides a way to self-regulate endogenous BMP-2 levels under healing conditions and in clinical examples when rhBMP-2 is delivered exogenously as part of a synthetic bone graft. Considerable effort has been focused on the exploration of controlling the amount of rhBMP-2 delivered at the implant site either through alternative carrier systems [18–20] or through the use of other delivery strategies [21–23]. …”

Section: Introductionmentioning

confidence: 99%

Surface-mediated delivery of siRNA from fibrin hydrogels for knockdown of the BMP-2 binding antagonist noggin

Kowalczewski

Saul

2015

Acta Biomaterialia

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Antagonists and inhibitory molecules responsible for maintaining tissue homeostasis can present a significant barrier to healing when tissue engineering/regenerative medicine strategies are employed. One example of this situation is the up-regulation of antagonists such as noggin in response to increasing concentrations of bone morphogenetic protein 2 (BMP-2) present from endogenous bone repair processes or delivered exogenously from biomaterials (synthetic bone grafts). While recombinant human (rh)BMP-2 delivered from synthetic bone grafts has been shown to be an effective alternative to autografts and allografts, the supraphysiological doses of rhBMP-2 have led to clinically-adverse side effects. The high rhBMP-2 dosage may be required, in part, to overcome the presence of antagonists such as noggin. Small interfering RNA (siRNA) is an appealing approach to overcome this problem because it can knock-down antagonists or inhibitory molecules in a temporary manner. Here, we conducted fundamental studies on the delivery of siRNA from material surfaces as a means to knock-down antagonists like noggin. Nonviral cationic lipid (Lipofectamine)-siRNA complexes were delivered from a fibrin hydrogel surface to MC3T3-E1 preosteoblasts that were treated with a supraphysiological dose of rhBMP-2 to achieve noggin mRNA expression levels higher than cells naïve to rhBMP-2. Confocal microscopy and flow cytometry showed intracellular uptake of siRNA in over 98% of MC3T3-E1 cells after 48 hours. Doses of 0.5μg and 1μg noggin siRNA were able to significantly reduce noggin mRNA to levels equivalent to those in MC3T3-E1 cells not exposed to rhBMP-2 with no effects on cell viability. Graphical Abstract

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Reduction of ectopic bone growth in critically-sized rat mandible defects by delivery of rhBMP-2 from kerateine biomaterials

Cited by 52 publications

References 30 publications

Alkylation of human hair keratin for tunable hydrogel erosion and drug delivery in tissue engineering applications

Alkylation of human hair keratin for tunable hydrogel erosion and drug delivery in tissue engineering applications

Keratin hydrogel carrier system for simultaneous delivery of exogenous growth factors and muscle progenitor cells

Surface-mediated delivery of siRNA from fibrin hydrogels for knockdown of the BMP-2 binding antagonist noggin

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