Electrospun polycaprolactone matrices with tensile properties suitable for soft tissue engineering.

The extracellular environment is a complex network of functional and structural components that impart chemical and mechanical stimuli that affect cellular function and fate. Cell differentiation on three dimensional scaffolds is also determined by the modulus of the substrate. Electrospun PCL nanofibers, which mimic the extra cellular matrix, have been developed with a wide variety of solvents and their combinations. The various studies have revealed that the solvents used influence the physical and mechanical properties, resulting in scaffolds with Young's modulus in the range of 1.8-15.4 MPa, more suitable for engineering of hard tissue like bone. The current study describes the use of benign binary solvent-generated fibrous scaffolds with a Young's modulus of 36.05 ± 13.08 kPa, which is almost 50 times lower than that of scaffolds derived from the commonly used solvents, characterized with myoblast, which can be further explored for applications in muscle and soft tissue engineering.

Electrospun type 1 collagen matrices preserving native ultrastructure using benign binary solvent for cardiac tissue engineering.

Electrospinning is a well-established technique that uses a high electric field to fabricate ultrafine fibrous scaffolds from both natural and synthetic polymers to mimic the cellular microenvironment. Collagen is one of the most preferred biopolymers, due to its widespread occurrence in nature and its biocompatibility. Electrospinning of collagen alone has been reported, with fluoroalcohols such as hexafluoroisopropanol (HFIP) and trifluoroethanol (TFE), but the resultant collagen lost its characteristic ultrastructural integrity of D-periodicity 67 nm banding, confirmed by transmission electron microscopy (TEM), and the fluoroalcohols used were toxic to the environment. In this study, we describe the use of glacial acetic acid and DMSO to dissolve collagen and generate electrospun nanofibers of collagen type 1, which is non-toxic and economical. TEM analysis revealed the characteristic feature of native collagen triple helical repeats, showing 67 nm D-periodicity banding pattern and confirming that the ultrastructural integrity of the collagen was maintained. Analysis by scanning electron microscopy (SEM) showed fiber diameters in the range of 200-1100 nm. Biocompatibility of the three-dimensional (3D) scaffolds was established by MTT assays using rat skeletal myoblasts (L6 cell line) and confocal microscopic analysis of immunofluorescent-stained sections of collagen scaffolds for muscle-specific markers such as desmin and actin. Primary neonatal rat ventricular cardiomyocytes (NRVCM) seeded onto the collagen scaffolds were able to maintain their contractile function for a period of 17 days and also expressed higher levels of desmin when compared with 2D cultures. We report for the first time that collagen type 1 can be electrospun without blending with copolymers using the novel benign solvent combination, and the method can be potentially explored for applications in tissue engineering.

Electrospun Type 1 Collagen Matrices Using a Novel Benign Solvent for Cardiac Tissue Engineering.

Electrospinning is a well-established technique that uses a high electric field to fabricate ultra fine fibrous scaffolds from both natural and synthetic polymers to mimic the cellular microenvironment. Collagen is one of the most preferred biopolymers due to its biocompatibility and widespread occurrence in nature. Electrospinning of Collagen alone has been reported with fluoroalcohols such as Hexafluoroisopropanol (HFIP) and Trifluoroethanol (TFE), which are toxic to the environment. In this study we describe the use of a novel benign binary solvent to generate nanofibers of Collagen type 1, which is non-toxic and economical. Transmission electron microscopy (TEM) analysis revealed the characteristic feature of native collagen namely the 67 nm banding pattern, confirming that the triple helical structure was maintained. Scanning Electron Microscopy (SEM) analysis showed the fiber diameters to be in the 200-800 nm range. Biocompatibility of the three dimensional (3D) scaffolds was established by MTT assays using skeletal myoblasts and Confocal Microscopic analysis of immunofluorescent stained sections for muscle specific markers such as Desmin and Actin. Primary neonatal rat ventricular cardiomyocytes seeded onto the scaffolds were able to maintain their contractile function for a period of 17 days. Our work provides evidence that Collagen 1 can be electrospun without combining with other polymers using a novel benign solvent and we are currently exploring the potential of this approach for cardiac and skeletal muscle tissue engineering. This article is protected by copyright. All rights reserved.

Karyotyping in retinoblastoma--a statistical approach.

PURPOSE: Karyotype analysis in hereditary retinoblastoma is considered to be of marginal value in risk prediction due to uncertainties in the assessment of 13q14 deletions. However, it is a low cost genetic test for retinoblastoma in developing countries. In the present study, the results of karyotype analysis were refined by a statistical method to overcome limitations. METHODS: Karyotype analysis was performed by trypsin-Giemsa banding and naked eye karyotyping for 33 bilateral, 25 unilateral and one regressed retinoblastoma patients. The percentage of metaphases with 13q14 deletions in each case was plotted on a scatter diagram. Normalization of the data was achieved by log transformation and the results were statistically analyzed by one-sample 't' test using SPSS version 9.0. RESULTS: Seven samples had 13q14 deletion percentages above the cutoff value. One-sample 't' test showed significance (p< 0.001). By this method, two unilateral and five bilateral patients had 13q14 deletions, constituting 11.8 % of cases. CONCLUSION: For accuracy, statistical analysis should be considered as an adjunct in karyotyping.