POLYGLYCOLIDE (PGA) POLYMER SCAFFOLDS
FOR TISSUE ENGINEERING

Tissue loss is one of the most common problems in human health care. Tissue Engineering has been defined as “The use of naturally occurring and/or synthetic materials in conjunction with cells to create biologic substitutes to serve as functional tissue replacements.” 1 In the late 1980’s researchers developed porous PGA polymer scaffolds that enabled scientists to grow thick (1 mm and greater) layers of tissue.2 Since then, a number of functional tissue equivalents have been grown in the laboratory including skin, cartilage, tendon, bone, blood vessels, bowel, bladder and liver.1,2,3,4,5,6,7,8,9

Scaffolds fabricated from PGA have proven useful for growing three-dimensional tissue equivalents in vitro.3,4,5,6,7,8,9 Small-diameter fibers of PGA or PLA are aligned or randomly entangled to form a strong, flexible and porous three-dimensional matrix. The scaffold allows cells to attach and grow in a three dimensional space while nutrient flow is maintained throughout the matrix.2

VWRCN sells PGA or PLA scaffolding available in two formats. The two formats are: aligned or non-aligned. The non-aligned Scaffolds are fabricated from spun fibers using a non-woven textile process, are sold as sheets 4 cm square and 2 mm thick and resemble felt. Further modifications of the basic scaffold material can be conducted in the laboratory to enhance cell attachment and growth5,6, 11 or to modify the physical properties and resorption rate of the non-aligned scaffold.10 Standard aligned scaffolds are also fabricated from spun fibers and are available in sheets 4 cm square and .5 mm thick, as well as tubes 4 mm in diameter and 4 cm long. A variety of custom three-dimensional shapes and tubular structures can be made with the aligned scaffolding. Custom sheets can vary in thickness from 50 to 2000 microns. Thicker structures can be made at a premium. The main advantage of the aligned scaffold is that structures, including tubing, are seamless, other scaffolds must be sutured.

VWRCN provides the scaffold as non-sterile. The scaffolds are packaged in pouches flushed with an inert gas and containing a desiccant pack. Upon opening, the scaffolds should be thoroughly washed in 100% isopropyl alcohol (IPA), followed by washing in sterile distilled water. In many applications, this washing procedure provides adequate sterilization and the scaffolds can be immediately incubated in media. If validated sterility is desired, the scaffolds should be washed thoroughly in IPA, drained and dried in a desiccated oven at 30 C for 30 minutes. Scaffolds can then be sterilized by ethylene oxide. The temperature should not exceed 30 C during the ethylene oxide sterilization cycle. E-Beam and Gamma sterilization may also be used, however, some deterioration of polymer properties will occur using these methods. These effects are minimized if the scaffold is kept at 0 C or below during irradiation. The scaffold should not be autoclaved.

Custom scaffolds made from polylactide (PLLA), PGA/PLLA copolymers and other synthetic resorbable polymers are available upon request. Please e-mail us at info@SCIDEMO.COM to inquire.

REFERENCES
1. Vacanti, J., Transplantation Society Abstracts, 1998 Meeting, Montreal
2. Ferber, D., Review Article, Science, Vol. 284, April 16, 1999, p. 422
3. Freed, L. et al, Biotechnology, Vol 12, July 1994, p. 689
4. Niklason, L. et al, Science, Vol 284, April 16, 1999, p. 489
5. Kim, B.S. et al, Biotechnol. Bioeng., (1998) 57(1), pp. 46-54
6. Kim, T.H., et al, Tissue Eng., (1997), 3(3), pp. 303-308
7. Vunjak-Novakovic, G. et al, J. Serb. Chem. Soc. (1997), 62(9), pp 787-799
8. Holder, W.D., et al, Tissue Eng., (1997), 3(2), pp 149-160
9. Grande, D. A. et al, J. Biomed. Mater. Res. , (1997), 34(2), pp 211-220
10. Mooney, D.J. et al, Biomaterials, (1996), 17(2), pp115-124
11. Gao, J. et al, J. Biomed. Mater. Res. , 42, 417 (1998).