Biomimetic Scaffolds Obtained by Electrospinning of Collagen-Based Materials: Strategies to Hinder the Protein Denaturation

The use of biomaterials and scaffolds to boost bone regeneration is increasingly gaining interest as a complementary method to the standard surgical and pharmacological treatments in case of severe injuries and pathological conditions. In this frame, the selection of biomaterials and the accurate assessment of the manufacturing procedures are considered key factors in the design of constructs able to resemble the features of the native tissue and effectively induce specific cell responses. Accordingly, composite scaffolds based on type-I-collagen can mimic the composition of bone extracellular matrix (ECM), while electrospinning technologies can be exploited to produce nanofibrous matrices to resemble its architectural organization. However, the combination of collagen and electrospinning reported several complications due to the frequent denaturation of the protein and the variability of results according to collagen origin, concentration, and solvent. In this context, the strategies optimized in this study enabled the preparation of collagen-based electrospun scaffolds characterized by about 100 nm fibers, preserving the physico-chemical properties of the protein thanks to the use of an acetic acid-based solvent. Moreover, nanoparticles of mesoporous bioactive glasses were combined with the optimized collagen formulation, proving the successful design of composite scaffolds resembling the morphological features of bone ECM at the nanoscale.

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Modulation of pulmonary alveolar type II cell phenotype and communication by extracellular matrix and KGF

AJP Cell Physiology ◽

10.1152/ajpcell.2001.281.4.c1291 ◽

2001 ◽

Vol 281 (4) ◽

pp. C1291-C1299 ◽

Cited By ~ 58

Author(s):

Brant E. Isakson ◽

Richard L. Lubman ◽

Gregory J. Seedorf ◽

Scott Boitano

Keyword(s):

Extracellular Matrix ◽

Growth Factor ◽

Type I Collagen ◽

Cultured Cells ◽

Cell Phenotype ◽

Alveolar Type ◽

Specific Cell ◽

Specific Marker ◽

Type I ◽

Type Ii

The alveolar epithelium consists of two cell types, alveolar type I (AT1) and alveolar type II (AT2) cells. We have recently shown that 7-day-old cultures of AT2 cells grown on a type I collagen/fibronectin matrix develop phenotypic characteristics of AT1 cells, display a distinct connexin profile, and coordinate mechanically induced intercellular Ca2+ changes via gap junctions (25). In this study, we cultured AT2 cells for 7 days on matrix supplemented with laminin-5 and/or in the presence of keratinocyte growth factor. Under these conditions, cultured AT2 cells display AT2 type morphology, express the AT2-specific marker surfactant protein C, and do not express AT1-specific cell marker aquaporin 5, all consistent with maintenance of AT2 phenotype. These AT2-like cells also coordinate mechanically induced intercellular Ca2+ signaling, but, unlike AT1-like cells, do so by using extracellular nucleotide triphosphate release. Additionally, cultured cells that retain AT2 cell-specific markers express connexin profiles different from cultured cells with AT1 characteristics. The parallel changes in intercellular Ca2+ signaling with cell differentiation suggest that cell signaling mechanisms are an intrinsic component of lung alveolar cell phenotype. Because lung epithelial injury is accompanied by extracellular matrix and growth factor changes, followed by extensive cell division, differentiation, and migration of AT2 progenitor cells, we suggest that similar changes may be vital to the lung recovery and repair process in vivo.

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Comparison of physical–chemical properties of type I collagen from different species

Food Chemistry ◽

10.1016/j.foodchem.2005.06.053 ◽

2006 ◽

Vol 99 (2) ◽

pp. 244-251 ◽

Cited By ~ 90

Author(s):

Yung Kai Lin ◽

Deng Cheng Liu

Keyword(s):

Type I Collagen ◽

Chemical Properties ◽

Type I ◽

Physical Chemical

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Temporal expression of PDGF receptors and PDGF regulatory effects on osteoblastic cells in mineralizing cultures

AJP Cell Physiology ◽

10.1152/ajpcell.1997.272.5.c1709 ◽

1997 ◽

Vol 272 (5) ◽

pp. C1709-C1716 ◽

Cited By ~ 52

Author(s):

X. Yu ◽

S. C. Hsieh ◽

W. Bao ◽

D. T. Graves

Keyword(s):

Osteoblast Differentiation ◽

Type I Collagen ◽

Receptor Expression ◽

Osteoblastic Cells ◽

Nodule Formation ◽

Specific Cell ◽

Type I ◽

Apparent Contradiction ◽

Tyrosyl Phosphorylation

Platelet-derived growth factor (PDGF) is mitogenic and chemotactic for osteoblastic cells in vitro. It is expressed during osseous wound healing and stimulates formation of new bone in vivo. PDGF stimulates cells by binding to specific cell surface receptors. The purpose of this study was to examine the effects of PDGF on osteoblastic proliferation and differentiation in long-term mineralizing cultures. Utilizing Northern blot analysis, we found that continuous PDGF treatment increased histone expression, indicative of enhanced proliferation, but suppressed osteoblast differentiation, demonstrated by inhibition of alkaline phosphatase, type I collagen, and osteocalcin expression. The inhibitory effect of PDGF on the differentiated function of osteoblasts was further established by findings that PDGF significantly inhibited nodule formation. The expression of PDGF receptors varied at different stages of culture. PDGF receptor mRNA expression increased when the cells had achieved a mature phenotype, during the stage of matrix maturation, and then decreased. However, as demonstrated by thymidine incorporation assays, the capacity of PDGF to stimulate DNA synthesis actually decreased during osteoblast maturation, as receptor expression increased. To investigate this apparent contradiction, tyrosyl phosphorylation and immunoblot assays were performed to assess changes in PDGF activation of their cognate receptors. The pattern of PDGF-induced tyrosyl phosphorylation remained relatively constant. This suggests that the diminished mitogenic activity of PDGF that occurs after osteoblast differentiation is regulated at a postreceptor level.

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Collagen fibrillogenesis in vitro: interaction of types I and V collagen

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142670 ◽

1986 ◽

Vol 44 ◽

pp. 210-211

Author(s):

Arthur J. Wasserman ◽

Kathy C. Kloos ◽

David E. Birk

Keyword(s):

Type I Collagen ◽

Corneal Stroma ◽

Minor Component ◽

Homogeneous Distribution ◽

Type I ◽

Type V Collagen ◽

Fibril Morphology ◽

Type V ◽

In Vitro Interaction

Type I collagen is the predominant collagen in the cornea with type V collagen being a quantitatively minor component. However, the content of type V collagen (10-20%) in the cornea is high when compared to other tissues containing predominantly type I collagen. The corneal stroma has a homogeneous distribution of these two collagens, however, immunochemical localization of type V collagen requires the disruption of type I collagen structure. This indicates that these collagens may be arranged as heterpolymeric fibrils. This arrangement may be responsible for the control of fibril diameter necessary for corneal transparency. The purpose of this work is to study the in vitro assembly of collagen type V and to determine whether the interactions of these collagens influence fibril morphology.

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