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Encouraging Vascular Regeneration using Bioactive Glass Microfibers

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Vascularization using bioactive glass

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Developments in tissue engineering over recent years have made possible the restoration of serious trauma.1 Using temporary scaffolds of biologically compatible substitutes, such as bioengineered tissue, damaged, injured or missing body tissues can be replaced.

With significant advances in the available scaffolds for use in tissue engineering, the provision of an adequate blood vessel system—vascularization— has become the key limitation to the regeneration of tissues after trauma.2

Several approaches have been used to achieve the necessary vascularization to supply sufficient blood to bioengineered tissue. These include loading the scaffold with angiogenic growth factors, such as vascular endothelial cell growth factor (VEGF), or endothelial cells and even prevascularization of the tissue to be implanted.2

Bioactive glasses have been shown to provide effective scaffolds for soft tissue engineering.1 They are biocompatible, lightweight and strong, and can be produced to degrade at a rate that matches the growth of new tissue.1 More recently, it has become apparent that bioactive glass also promotes angiogenesis that is important for supporting new tissue growth.

This article explores the potential of bioactive glass to enhance vascular regeneration.

 

The Need for Tissue Engineering After Trauma

The human body has a remarkable ability to heal itself after undergoing trauma. However, such healing is a complex biological process requiring many different cell types to complete the necessary steps at the right time.3 If large amounts of tissue have been lost, tissue engineering is used to provide a temporary biomaterial scaffold to provide the necessary support or shape while the new tissue grows.

Initially, damaged blood vessels must constrict to stem blood loss but then they are required to regenerate to provide nutrients to the new tissue created to restore the damage. Vascular regeneration is thus an important step in the healing process. If there is not an adequate vascular system, the nutrients required for growth cannot be supplied.

Bioactive glass, by virtue of its biocompatibility, strength and range of achievable properties, is widely used to provide support in tissue engineering and been used with much success in the repair of bone, soft tissue and cartilage repair.1 Once implanted in the body, reactions occur on the surface of bioactive glass that facilitate bonding with existing tissue. Furthermore, bioactive glass can release ions, such as calcium that is important for regeneration of skin and bone, that are needed to support regeneration and promote rapid bone formation.4

More recently it has also become apparent that bioactive glass can promote vascularization without the need for adding growth factors to the scaffold.5-7

 

Bioactive Glass can Accelerate Healing

Bioactive glass is a valuable tool in tissue engineering. Although originally used to facilitate bone repair, it has also provided tremendous benefit when included as a component of bioscaffold materials used in soft tissue repair. Bioactive glass has been shown to speed up healing and has the added benefit that its rate of resorption can be tailored to meet a particular repair need.1

A novel form of borate bioactive glass has been successfully used in wound healing.8 A fibrous network of calcium-rich glass fibers forms a scaffold to promote skin regeneration. When this bioactive glass was used in patients with diabetic ulcers who were at risk of limb amputation, the skin was fully repaired in almost two thirds of cases after a few months with little if any scarring.8

More recently, it has been shown that bioactive glass actively enhances tissue regeneration by stimulating the secretion of angiogenic growth factors that promote the proliferation of microvascular endothelial cells and enhance revascularization.5,6 Thus, bioactive glass is able to augment a critical process in tissue regeneration.7 This allows more rapid tissue repair without the need for adding recombinant inductive growth factors.

 

Conclusion

Bioactive glass is established as a key tool in a range of tissue engineering applications. It promotes the repair of bone and soft tissue whilst providing structural support. Furthermore, the bioactive glass can be designed to last just as long as is needed for the new tissue to gain the necessary volume and strength for the repair to be completed.

In addition, it has been shown that bioactive glass also increases the levels of angiogenic growth factor, which accelerate vascular regeneration. Vascularization is a key process in tissue repair since blood vessels are required to provide the nutrient for new tissue to develop and grow. Previously, recombinant growth factors were added to tissue engineering scaffolds to promote the creation of new blood vessels. This extra process can now be obviated by including bioactive glass as a component of the scaffold material.

Proangiogenic potential is thus another desirable quality that can be added to the properties of bioactive glass. This further supports the use of bioactive glass in temporary healing scaffolds during tissue engineering procedures.

Mo-Sci produces medical implant grade bioactive glass in a range of formats suitable for use in a wide variety of tissue engineering scaffolds and can tailor its composition to meet specific requirements.9

 

References

  1. Rahaman MN, Day DE, Bal S, et al. Bioactive glass in tissue engineering. Acta          Biomaterialia 2011;7:2355 2373.

  2. Baiguera S and Ribatti D. Endothelialization approaches for viable engineered tissues. Angiogenesis. 2013 Jan;16(1):1 14.

  3. Guo S, and DiPietro LA. Factors Affecting Wound Healing. J Dent Res. 2010;89(3): 219–229.

  4. Gerhardt L-C and Boccaccini AR. Bioactive Glass and Glass-Ceramic Scaffolds for Bone Tissue Engineering. Materials 2010;3:3867 3910.

  5. Day RM, et al. Bioactive glass stimulates the secretion of angiogenic growth factors and angiogenesis in vitro. Tissue Eng. 2005 May-Jun;11(5-6):768 77.

  6. Leu A and Leach JK. Proangiogenic Potential of a Collagen/Bioactive Glass Substrate. Pharmaceutical Research 2008;25 (5):1222–1229.

  7. Gorustovich A, et al. Effect of bioactive glasses on angiogenesis: In-vitro and in-vivo evidence: A review. Tissue Eng. Part B Rev. 2010;16:199 207.

  8. The American Ceramic Society Press release 4 May 2011. Available at https://www.sciencedaily.com/releases/2011/05/110503133056.htm

  9. Mo Sci Corporation website. http://www.mo-sci.com/