TGF-β Activity Related to the Use of Collagen Membranes: In Vitro Bioassays

Abstract

Collagen membranes commonly used in guided bone regeneration are supposed to actively influence tissue regeneration and are not exclusively serving as passive barriers shielding away the soft tissue. The molecular mechanisms by which collagen membranes might affect tissue regeneration might involve the activation of transforming growth factor beta (TGF-β) signaling pathways. Here, we determined the TGF-β activity of supernatants and proteolytic lysates of five commercially available collagen membranes. The expression of TGF-β target genes interleukin 11 (IL11), NADPH oxidase 4 (NOX4), and proteoglycan 4 (PRG4) was evaluated by reverse transcriptase polymerase chain reaction and IL11 immunoassay in gingival fibroblasts. TGF-β signaling activation was further assessed by blocking the TGF-β receptor I kinase, a TGF-β neutralizing antibody, and showing the nuclear localization of phosphorylated Smad3 and total Smad2/3. We could identify two collagen membranes whose supernatants and lysates caused a robust increase of TGF-β receptor I kinase-dependent expression of IL11 in gingival fibroblasts. Moreover, the supernatant of a particular one membrane caused the nuclear localization of phosphorylated Smad3 and Smad2/3 in the fibroblasts. These results strengthen the evidence that some collagen membranes possess an intrinsic TGF-β activity that might actively influence the process of guided bone regeneration.

Proteomic Analysis of Porcine-Derived Collagen Membrane and Matrix

“…Even though not identified by the proteomic analysis, collagen membranes contain growth factors such as TGF-β [ 60 ]. However, and consistent with the proteomic analysis, neither the collagen membrane nor the matrix holds an intrinsic TGF-β activity based on a bioassay [ 61 ]. It is more likely that locally released growth factors, such as TGF-β, adsorb to the collagen and SLRPs, thus changing the biological behavior in vivo.…”

Osteoconductive Properties of a Volume-Stable Collagen Matrix in Rat Calvaria Defects: A Pilot Study

“…Even though VSCM failed to release detectable amounts of TGF-β activity into an aqueous extraction [36], the endogenous TGF-β may support the chondrogenic differentiation of the invading mesenchymal cells [36,37]. The role of TGF-β to support chondrogenic differentiation remains at the level of a hypothesis.…”

Active and Passive Mineralization of Bio-Gide® Membranes in Rat Calvaria Defects

“…Collagen membranes are usually of xenogeneic origin, having been subjected to a sequential series of processing steps that basically remove most of the original cellular components, ending up with a sterile ready-to-use biomaterial. However, the collagen membranes maintain the structural [ 8 , 9 ] and biochemical properties [ 9 , 10 ] of the original tissue. Moreover, the intrinsic biological activity of collagen membranes is reflected by in vitro bioassays, including those that test the activity of the conditioned medium [ 10 ], the adsorption of growth factors [ 11 , 12 ], and the cellular response upon seeding [ 9 , 13 ].…”

“…However, the collagen membranes maintain the structural [ 8 , 9 ] and biochemical properties [ 9 , 10 ] of the original tissue. Moreover, the intrinsic biological activity of collagen membranes is reflected by in vitro bioassays, including those that test the activity of the conditioned medium [ 10 ], the adsorption of growth factors [ 11 , 12 ], and the cellular response upon seeding [ 9 , 13 ]. In the clinical scenario, however, the collagen membranes are usually moistened with blood from the defect region, where, similar to wound healing, the collagen is inflated by the blood, and the healing cascade is initiated—with neutrophils and macrophages invading the spongy part of the membrane [ 14 ].…”