Hello

There is a main question!

What kind of tissue do you want to work on?

@Mohammad Khorsand-Ghayeni

Well being a design engineer my main focus is to consider various scaffold design for various tissue and try to find the key point that are consider in designing these scaffolds. So i do not have a specific tissue that i want to work but yes if you suggest some scaffold design for specific tissue it will also be meaningful for me.

Thanks

Hi, to be synthetic, some key parameters are:

-structure: massive, porous or not (which size of pores...), fibrous, micro/nanostructuration

-composition: synthetic or natural material(s)

-physico-chemical properties: hydrophobicity/hydrophilicity, biocompatibility (in vitro and in vivo), bioactivity (functionalization of the scaffolds for a given cell type?), biodegradability (in vitro and in vivo)

I would also add mechanical properties such as Young's modulus.  The characterization methods will vary but normally we do SEM to quickly evaluate the geometry but then concentrate on the biological assays.  In particular, fluorescence microscopy after tagging appropriate structures (e.g. nuclei with DAPI, actin with phalloidin, live/dead staining) to show where the cells are and their health qualitatively.

A simple start would be a woodpile scaffold composed of alternating layers of parallel lines.  It can get as complex as you'd like.

I don't quite understand question 4 but most scaffolds are not designed to be removed; they either stay in or are degraded entirely. 

Hi,

In general, the materials using in scaffold design are basically from the natural-derived biomaterials [including protein-based biomaterial (collagen, chitosan, silk etc.) and polysaccharide-based biomaterials (cellulose, chitin/chitosan, alginate etc.)]. This is mainly due to their chemical composition similar to the tissues, high biocompatibility therefore they are believed to be more fully integrated into the surrounding tissues and hence more easily in remodelling in respond to changes in tissue need. Parameters that you need to consider for optimum scaffold structure are biocompatibility, biodegradation, mechanical support, porosity, pore size, interconnectivity, elasticity and so on.

Hi Zulfiqar

1. There are so many methods for producing scaffolds and it depends on your application. You can make an injectable hydrogel for soft tissue reconstruction or make a calcium phosphate based bioceramic for bone tissue engineering. Electrospinning, solid casting, molding pre-gelled solutions and so many other methods are available. First of all, you need to know what is your final application.

2,3. Porosity, mechanical properties of the scaffold (Young's modulus and Rheological properties), degradation of the scaffold facing the PBS in different pH or enzymes, swelling ratio of hydrogels, morphological investigations by SEM or TEM, densitometry and etc. Again, it depends on the type of the scaffold and application. Electrical properties, for instance, are important for nerve and muscle applications but not for skin tissue engineering.

4. Basically, you don't need to remove the tissue from the scaffold and actually you can't do it. You need to use the whole system in vivo to see how the recipient's body would respond to your structure.

What I would suggest is to look for a particular application and read some literature on that one. You will get some good insight on what should be done and what is needed when designing a scaffold. Each tissue has its own characteristics and you cannot pursue one method for all the applications.

Good luck with your research!