Biomedical Engineering Reference
In-Depth Information
Table 14.1
Characteristics of the Growth Factors Used in Tissue Engineering
Growth Factor
Isoelectric
Point (IEP)
Molecular
Weight (kDa)
Biological
Substances for
Growth Factor
Binding
Functions of Growth Factor
Basic fibroblast
growth factor
(bFGF)
9.6
16
Heparin or heparan
sulfate
Stimulating the cells involved
in the healing process
(bone, cartilage, nerve, etc),
angiogenesis
Transforming
growth TGF-
β
1
(TGF-
β
1)
9.5
25
Heparin or heparan
sulfate
Enhancing the wound healing,
stimulating the osteoblast
proliferation to enhance bone
formation
Collagen type IV
Latency associated
protein
Latent TGF-
b
1
binding protein
Bone
morphogenetic
protein-2 (BMP-2)
8.5
32
Collagen type IV
Stimulating the MSCs to
osteoblast lineage and
inducing the bone formation
both at bone and ectopic sites
Vascular endothelial
growth factor
(VEGF)
8.5
38
Heparin or heparan
sulfate
Stimulating the endothelial cell
growth, angiogenesis, and
capillary permeability
Hepatocyte growth
factor (HGF)
5.5
100
Heparin or heparan
sulfate
Stimulating of matrix
remodeling and epithelial
regeneration (liver, spleen,
kidney, etc.)
14.4
CONTROLLED RELEASE TECHNOLOGY
The controlled release of drugs such as proteins, growth factors, genes, and siRNAs is a main objec-
tive of DDS. The success of the controlled release of a drug for the required duration of time with
the optimum release mode depends on various factors, such as the physicochemical properties of the
drug and the drug-carrier matrix, type of dosage form, and the administration route. Successful drug
delivery has enormous academic, clinical, and practical impacts on gene therapy, cell and molecular
biology, pharmaceutical and food industries, and production of biotechnology products. The objective
of drug delivery involves the controlled release of drug, the prolongation of drug life-span, the accel-
eration of drug absorption, and the drug targeting. To achieve these objectives, a tremendous volume
of research has been performed. For example, drug has been chemically coupled with various water-
soluble polymers to enlarge the apparent molecular size, which allows the drug to prolong the serum
half-life period, in addition to encapsulation into nanocarriers including polymeric nanospheres,
polymer micelles, lipid emulsion, and liposomes
[17-22]
. Drug is often modified with the polymers
and polymer micelles to cover the molecular surface by a hydrophilic layer, which results in reduced
exclusion of the drug from blood circulation by the mononuclear phagocyte system (MPS) present in
the liver and spleen
[23-26]
. Thus, this polymeric modification prolongs the
in-vivo
life-span of the
