Bone morphogenetic protein‐2 decorated silk fibroin films induce osteogenic differentiation of human bone marrow stromal cells

Abstract

Bone morphogenetic protein (BMP)-2 has a critical role in bone formation and regeneration. Therefore, the ability to immobilize this molecule in certain matrices may be crucial in bone tissue engineering. Using carbodiimide chemistry, BMP-2 was directly immobilized on silk fibroin films. Whereas human bone marrow stromal cells cultured on unmodified silk fibroin films in the presence of osteogenic stimulants exhibited little if any osteogenesis, the same cells cultured on BMP-2 decorated films in the presence of osteogenic stimulants differentiated into an osteoblastic lineage as assessed by their significantly elevated alkaline phosphatase activity, calcium deposition, and higher transcript levels of collagen type I, bone sialoprotein, osteopontin, osteocalcin, BMP-2, and cbfa1. Using cell culture inserts, it was demonstrated that differentiation was induced by the immobilized protein and not by protein released into the culture medium. Comparison with a similar amount of medium-supplemented BMP-2, where no additional protein was added with medium changes, showed that delivery of BMP-2 immobilized on the biomaterial surface was more efficient than soluble delivery. The results illustrate that BMP-2 covalently coupled on silk biomaterial matrices retains biological function in vitro based on the induction of osteogenic markers in seeded bone marrow stromal cells.

The use of silk-based devices for fracture fixation

“…After 4 and 8 week time points in vivo, there was early resorption of the silk screw. Future material iterations may involve the incorporation of bioactive compounds such as BMP-2 to promote bone ingrowth or antibiotics to prevent infection [19][20][21][22][23]32,33 . Such factors can be used to modulate healing and promote remodelling of bone.…”

“…Silk is selected due to its robust mechanical features, biocompatibility and FDA-approved (Allergan Medical, Inc.) uses in medical devices. It is degradable in vivo with controllable rates from days to years and has the capability of being functionalized with bioactive compounds [18][19][20][21][22][23][24] . Moreover, silk materials maintain structural stability to 4170°C, are stable at extremes of pH and can be autoclaved for sterilization, all features that enhance potential utility in new medical devices when added to the mechanical features and biocompatibility 25,26 .…”

Silk polymer-based adenosine release: Therapeutic potential for epilepsy

“…Silk has been previously explored as a vehicle for drug delivery in the form of drug entrapping films [26], as drug encapsulating microspheres [27] and via silk and drug nanofilm deposition or coatings [27,28]. Peptides and proteins also have previously been chemically coupled to silk fibroin using carbodiimide chemistry [29,30].…”

Non-invasive characterization of structure and morphology of silk fibroin biomaterials using non-linear microscopy

“…[18,38,38,39,53]. This information is made readily available via three-dimensional reconstructions of TPEF-based optical sections, as shown in Figure 3 and 4.…”