Yingke_Wu

Publication date: August 2015
Source:Biomaterials, Volume 61
Author(s): Nathan A. Hotaling , Kapil Bharti , Haydn Kriel , Carl G. Simon Jr.
Despite the growing use of nanofiber scaffolds for tissue engineering applications, there is not a validated, readily available, free solution for rapid, automated analysis of nanofiber diameter from scanning electron microscope (SEM) micrographs. Thus, the goal of this study was to create a user friendly ImageJ/FIJI plugin that would analyze SEM micrographs of nanofibers to determine nanofiber diameter on a desktop computer within 60 s. Additional design goals included 1) compatibility with a variety of existing segmentation algorithms, and 2) an open source code to enable further improvement of the plugin. Using existing algorithms for centerline determination, Euclidean distance transforms and a novel pixel transformation technique, a plugin called “DiameterJ” was created for ImageJ/FIJI. The plugin was validated using 1) digital synthetic images of white lines on a black background and 2) SEM images of nominally monodispersed steel wires of known diameters. DiameterJ analyzed SEM micrographs in 20 s, produced diameters not statistically different from known values, was over 10-times closer to known diameter values than other open source software, provided hundreds of times the sampling of manual measurement, and was hundreds of times faster than manual assessment of nanofiber diameter. DiameterJ enables users to rapidly and thoroughly determine the structural features of nanofiber scaffolds and could potentially allow new insights to be formed into fiber diameter distribution and cell response.

Abstract

Publication date: September 2015
Source:Biomaterials, Volume 63
Author(s): Keiko Yoshizawa , Ryo Mizuta , Tetsushi Taguchi
The bonding behavior of hexanoyl (Hx: C6) group-modified alkaline-treated gelatin (HxAlGltn) porous films ((P)HxAlGltn) on the porcine intestine was evaluated. (P)HxAlGltns with various porosities were prepared by the salt-leaching method for various solid–liquid ratios. (P)HxAlGltns bonded more strongly to porcine intestine surfaces than did porous AlGltn films ((P)AlGltns). L929 cells cultured on (P)HxAlGltns showed adhesivity than cells cultured on (P)AlGltns. Faster tissue infiltration and a shorter degradation time of highly porous (P)HxAlGltns were observed after implantation in rat subcutaneous tissues. The angiogenic markers CD34 and α-SMA were highly expressed around (P)HxAlGltns that had high porosity. These results indicated that highly porous (P)HxAlGltns have advantages with respect to not only bonding strength on wet soft tissues, but also angiogenesis.

Nature Materials. doi:10.1038/nmat4294

Authors: Donald R. Griffin, Westbrook M. Weaver, Philip O. Scumpia, Dino Di Carlo & Tatiana Segura

Publication date: July 2015
Source:Biomaterials, Volume 58
Author(s): Min Kyung Lee , Max H. Rich , Jonghwi Lee , Hyunjoon Kong
Bioactive hydrogels have been extensively studied as a platform for 3D cell culture and tissue regeneration. One of the key desired design parameters is the ability to control spatial organization of biomolecules and cells and subsequent tissue in a 3D matrix. To this end, this study presents a simple but advanced method to spatially organize microchanneled, cell adherent gel blocks and non-adherent ones in a single construct. This hydrogel system was prepared by first fabricating a bimodal hydrogel in which the microscale, alginate gel blocks modified with cell adhesion peptides containing Arg-Gly-Asp sequence (RGD peptides), and those free of RGD peptides, were alternatingly presented. Then, anisotropically aligned microchannels were introduced by uniaxial freeze-drying of the bimodal hydrogel. The resulting gel system could drive bone marrow stromal cells to adhere to and differentiate into neuron and glial cells exclusively in microchannels of the alginate gel blocks modified with RGD peptides. Separately, the bimodal gel loaded with microparticles releasing vascular endothelial growth factor stimulated vascular growth solely into microchannels of the RGD-alginate gel blocks in vivo. These results were not attained by the bimodal hydrogel fabricated to present randomly oriented micropores. Overall, the bimodal gel system could regulate spatial organization of nerve-like tissue or blood vessels at sub-micrometer length scale. We believe that the hydrogel assembly demonstrated in this study will be highly useful in developing a better understanding of diverse cellular behaviors in 3D tissue and further improve quality of a wide array of engineered tissues.

Article

Electrospinning is a useful method of biomaterial fabrication, but a lack of bioactivity in the final construct can limit their application as mimics for biological matrices. Here, the authors fabricate a degradable electrospun scaffold as an in vitro and in vivo mimic of the extracellular matrix.

Nature Communications doi: 10.1038/ncomms7639

Authors: Ryan J. Wade, Ethan J. Bassin, Christopher B. Rodell, Jason A. Burdick

Nature Materials. doi:10.1038/nmat4157

Authors: Ted T. Lee, José R. García, Julieta I. Paez, Ankur Singh, Edward A. Phelps, Simone Weis, Zahid Shafiq, Asha Shekaran, Aránzazu del Campo & Andrés J. García

Publication date: June 2015
Source:Biomaterials, Volume 52
Author(s): Gang Chen , Jinlong Chen , Bo Yang , Lei Li , Xiangyou Luo , Xuexin Zhang , Lian Feng , Zongting Jiang , Mei Yu , Weihua Guo , Weidong Tian
In tissue engineering, scaffold materials provide effective structural support to promote the repair of damaged tissues or organs through simulating the extracellular matrix (ECM) microenvironments for stem cells. This study hypothesized that simulating the ECM microenvironments of periodontium and dental pulp/dentin complexes would contribute to the regeneration of tooth root. Here, aligned PLGA/Gelatin electrospun sheet (APES), treated dentin matrix (TDM) and native dental pulp extracellular matrix (DPEM) were fabricated and combined into APES/TDM and DPEM/TDM for periodontium and dental pulp regeneration, respectively. This study firstly examined the physicochemical properties and biocompatibilities of both APES and DPEM in vitro, and further investigated the degradation of APES and revascularization of DPEM in vivo. Then, the potency of APES/TDM and DPEM/TDM in odontogenic induction was evaluated via co-culture with dental stem cells. Finally, we verified the periodontium and dental pulp/dentin complex regeneration in the jaw of miniature swine. Results showed that APES possessed aligned fiber orientation which guided cell proliferation while DPEM preserved the intrinsic fiber structure and ECM proteins. Importantly, both APES/TDM and DPEM/TDM facilitated the odontogenic differentiation of dental stem cells in vitro. Seeded with stem cells, the sandwich composites (APES/TDM/DPEM) generated tooth root-like tissues after being transplanted in porcine jaws for 12 w. In dental pulp/dentin complex-like tissues, columnar odontoblasts-like layer arranged along the interface between newly-formed predentin matrix and dental pulp-like tissues in which blood vessels could be found; in periodontium complex-like tissues, cellular cementum and periodontal ligament (PDL)-like tissues were generated on the TDM surface. Thus, above results suggest that APES and DPEM exhibiting appropriate physicochemical properties and well biocompatibilities, in accompany with TDM, could make up an ECM microenvironment for tooth root regeneration, which also offers a strategy for complex tissue or organ regeneration.

Publication date: April 2015
Source:Biomaterials, Volume 46
Author(s): Fan Wei Meng , Peter F. Slivka , Christopher L. Dearth , Stephen F. Badylak
Extracellular matrix (ECM) derived from a variety of source tissues has been successfully used to facilitate tissue reconstruction. The recent development of solubilized forms of ECM advances the therapeutic potential of these biomaterials. Isolated, soluble components of ECM and matricryptic peptides have been shown to bias macrophages toward a regulatory and constructive (M2-like) phenotype. However, the majority of studies described thus far have utilized anatomically and morphologically similar gastrointestinal derived ECMs (small intestine, esophagus, urinary bladder, etc.) and a small subset of macrophage markers (CD206, CD86, CCR7) to describe them. The present study evaluated the effect of solubilized ECM derived from molecularly diverse source tissues (brain and urinary bladder) upon primary macrophage phenotype and function. Results showed that solubilized urinary bladder ECM (U-ECM) up-regulated macrophage PGE2 secretion and suppressed traditional pro-inflammatory factor secretion, consistent with an M2-like phenotype. The hyaluronic acid (HA) component in solubilized U-ECM played an important role in mediating this response. Brain ECM (B-ECM) elicited a pro-inflammatory (M1-like) macrophage response and contained almost no HA. These findings suggest that the molecular composition of the source tissue ECM plays an important role in influencing macrophage function and phenotype.