Scaffolds, Growth Factors, and Tissue Constructs Hasan Uludag Department of Chemical & Materials Engineering, Department of Biomedical Engineering, and Faculty of Pharmacy & Pharmaceutical Sciences, University of Alberta, Edmonton, AB Delivery Systems

Bone Healing: an orchestrated process of molecular and cellular events Hematoma Angiogenesis Influx of Stem Cells Osteogenic Differentiation Bone Deposition Remodelling chemotaxis, proliferation, differentiation, osteogenesis, and apoptosis all processes regulated by growth factors and the extracellular matrix Shier D. et al., Hole's Human Anatomy & Physiology, 1996.

Approaches for Bone Regeneration: Extracellular Matrices: dynamic scaffolding capable of modulating cell activity: natural (collagen) or synthetic (apatite fillers) Growth Factors: endogenous regulators of cellular activity: chemotaxis, proliferation, and differentiation (BMPs) Osteogenic Cells: cells that can differentiate under the influence of local factors (bone marrow cells or engineered cells)

A Brief History of BMP Development 1965 ~ Description of bone morphogenetic activity from demineralized bone matrix (M. Urist, Science) 1988 ~ Cloning of recombinant human BMP-2 and reproduction of BMP activity by a single protein (Wozney et al., Science) ~ Development of a delivery system >2000 ~ Regulatory approval, publications on specific clinical indications, success rates, and alternatives. TORONTO BOSTON GENETICS INSTITUTE INC.

Osteoinductive Devices in Clinics BMP-2 Soaked Collagen SpongeWet Sponge in Fusion Cage Demineralized Bone Powder to be Soaked with OP-1 (BMP-7)

Representation of an Osteoinductive Device cell flux BMP release biomaterial scaffold

Effect of biomaterial scaffold on BMP release kinetics from implants release kinetics ≈ 'retention' Subsequent Pharmacokinetics Initial (3 hr) Recovery of 125 I-BMP-2 in Rat Ectopic Model

Retention of different BMPs in implants Collagen SpongePoly(glycolic acid) Time (days) Percent Retention

Relationship between BMP retention and osteoinductive activity in implants Strategy-1 Biomaterial-1 Biomaterial-2 BMP-X Strategy-2 Biomaterial BMP-Y BMP-Z

BMP-2 vs. BMP-4: Comparison of protein retention and bone formation in the rat ectopic model Pharmacokinetics Osteoinduction

O N H NiPAM (N-isopropylacrylamide) O O R Alkyl-methacrylates O O N O O NASI (N-acryloxysuccinimide) Engineered biomaterials for increased retention of BMPs after injection NiPAM/EMA-49 kD NiPAM/EMA/NASI-50 kD NiPAM/EMA-404 kD NiPAM/EMA/NASI-422 kD Temperature-Sensitive Polymers BMP-biomaterial interactions BMPs

BMP-2 Retention by NiPAM-Polymers (intramuscular injection model in rats) Time (days) % Retention

An Osteoinductive Device by Gene Delivery cell flux release of osteoinductive (BMP-2) genes biomaterial scaffold... Lieberman et al. (UCLA) Huard et al. (U. Pittsburg) Helm et al. (U. Virginia) 1999.

Medicinal Agent Medicinal Agent Growth Factors for Systemic Bone Therapy BP conjugation as a means to impart bone affinity (Zhang et al., Chem. Soc. Rev. 2006) Bisphosphonates Protein

Protein chemistry to couple bisphosphonates therapeutic proteins sulfoSMCC aminoBP ( ) sulfoSMCC Protein Medicinal Agent

New bisphosphonates engineered specifically for targeting proteins to bone Medicinal Agent (Bansal et al., J. Pharm. Sci. 2004; Bansal et al., Angew Chem. 2005) Di-Bisphosphonate Tetra-Bisphosphonate

Effectiveness of BP-coupled proteins to seek bone after systemic administration ? Targeting Efficiency: Bone Delivery of BP-Conjugate Bone Delivery of Native Protein Medicinal Agent (Zhang et al., Chem. Soc. Rev. 2006)

ACKNOWLEDGEMENTS Co-workers and Collaborators S. Gittens G. Bansal T.J. Gao G. Wohl S. ZhangT. Haque A. Jalil J. Yang C. KucharskiJ.E.I. Wright J. Wozney (Genetics Institute) W. Sebald (U. of Würzburg) R.F. Zernicke, J.R. Matyas (UC) A. Lavasanifar (UA) Financial Support Canadian Institutes of Health Research, AHFMR/CFI,Genetics Institute Inc., Millenium Biologics, Whitaker Foundation, NSERC