Construction of Collagen Scaffolds That Mimic the Three-Dimensional Architecture of Specific Tissues

Abstract

Every tissue and organ has its own 3-dimensional (3D) extracellular matrix (ECM) organization. Cells in a 3D bioscaffold for tissue engineering typically align new ECM components according to the bioscaffold provided. Therefore, scaffolds with a specific 3D structural design resembling the actual ECM of a particular tissue may have great potential in tissue engineering. Here, we show that, using specific freezing regimes, 3D scaffolds that mimic the 3D architecture of specific tissues can be made from collagen. Three examples are given, namely, scaffolds resembling the cup-shaped parenchymal (alveolar) architecture of lung, scaffolds that mimic the parallel collagen organization of tendon, and scaffolds that mimic the 3D organization of skin. For the preparation of these tissue-specific scaffolds, we relied on simple techniques without the need for expensive or customized equipment. Freezing rate, type of suspension medium, and additives (e.g., ethanol) were found to be prime parameters in controlling scaffold morphology.

Novel Freeze-Drying Methods to Produce a Range of Collagen–Glycosaminoglycan Scaffolds with Tailored Mean Pore Sizes

“…The effects of T f on pore structure in scaffolds produced from a variety of biomaterials have been investigated in previous studies. [22][23][24][25] However, in these studies, the cooling rate was also varied in conjunction with T f , making it difficult to determine the specific mechanisms behind changes in pore structure. Several studies have investigated the effects of cooling rate on the pore structure of freeze-dried scaffolds.…”

“…Annealing times of 0. 25,6,12,18, and 48 h were used to determine the effects of annealing on pore size (Fig. 2, E).…”

“…22,25 However, a study by O'Brien et al 13 has shown that cooling rate also affects the uniformity of the pore structure. It was found that a cooling rate of 0.98C=min produced scaffolds with homogeneous pore structure, whereas quicker or slower cooling rates reduced the uniformity of the structure formed.…”

“…This allowed control of the cooling rate and eliminated the possibility of sample thawing during transport between the freezing and drying apparatus, which were separate devices in many studies. 22,23,25 The use of annealing to alter the pore size of a freeze-dried scaffold is a novel aspect of this study. Annealing has been used previously to encourage crystallization and reduce the drying cycle times of pharmaceuticals, 17,26,27 but has yet to be investigated for its effects on the structure of freeze-dried scaffolds.…”

In VivoMagnetic Resonance Imaging of Type I Collagen Scaffold in Rat: Improving Visualization of Bladder and Subcutaneous Implants

“…This most likely represented the stored bulk water present in the honeycomb structure and large interstitial spaces of the collagen scaffold. 28 After implantation, the PBS in the scaffold would be replaced by body fluids, maintaining the hyperintense appearance of the scaffold in MR images. In contrast, the COL-USPIO scaffold showed a region of hypointensity but this quickly disappeared within 2 weeks.…”