**Author details**

*Alginates - Recent Uses of This Natural Polymer*

articular cartilage defects in mice [84].

the regeneration of cardiac tissue [87].

Finally, TGF-β1-releasing alginate hydrogels have been used to promote chondrogenesis of MSCs, demonstrating in vitro increase of chondrogenic markers and healing of

Another important application of alginate/MSC constructs is the treatment of myocardial lesions. Yu et al. combined RGD-functionalized alginate hydrogels with human bone marrow MSCs showing that they could improve left ventricular function after myocardial infarction in a rat acute myocardial infarction model [85]. Cyclic RGD in alginate hydrogels has been also shown to promote neoangiogenesis and cardiac neovascularization, improving cardiac function in animals postmyocardial infarction [86]. Finally, when alginate hydrogels are used for cardiac regeneration, it has been shown that G-type alginates possess properties suited for

MSCs have been combined with alginate hydrogels for tendon repair purposes in animal model of tendon tears. For example, rat Achilles tendon lesions have been treated with hydrogels loaded with MSCs [88] showing healing of higher quality than surgical meshes and sutures. In addition, RGD-functionalized hydrogels loaded with TGF-β3 and loaded with periodontal and gingival MSCs were found to efficiently produce tendon tissue when implanted subcutaneously in mice [89]. Alginate hydrogels have also been widely utilized as wound dressings either alone or in combination with MSCs. For this application, various types of MSCs have been used including umbilical cord MSCs [90] and bone marrow MSCs in

Finally, alginate hydrogels have been used to protect MSCs from the local immune response elicited when allogeneic cells are implanted in vivo. They have been shown to provide protection from the immune system increasing the survival of MSCs in the hostile environment of the host-releasing immunomodulatory

In conclusion, alginate/MSC constructs have been used for a wide variety of regenerative medicine applications, ranging from musculoskeletal to cardiac tissue repair. MSCs isolated from adult and fetal tissues have been combined with alginate hydrogels functionalized with extracellular matrix components, minerals, and other natural polymers and evaluated in vitro and in vivo. In vitro studies demonstrated the ability of alginate hydrogel at different formulations to support MSC growth and differentiation toward several lineages, whereas in vivo data have shown that when alginate-based materials are combined with MSCs, they can achieve successful healing of bone and cartilage defects, myocardial tissue after myocardial infarction, tendon tears, and skin wound. Nonetheless, evaluation of safety and efficacy of the constructs is required prior to clinical use. Existing in vitro and in vivo data demonstrate the potential of alginates to play an important future role in regenerative medicine, reaching the bedside and achieving regenera-

alginate-chitosan hydrogels with antibacterial properties [66].

**72**

factors [91].

**4. Conclusions**

tion of damaged tissues.

**Conflict of interest**

The authors declare no conflict of interest.

Michail E. Klontzas1,2, Hicham Drissi3 and Athanasios Mantalaris2 \*

1 Wallace H. Coulter Department of Biomedical Engineering, Biomedical Systems Engineering Laboratory, Georgia Institute of Technology, Atlanta, GA, USA

2 School of Medicine, Winship Cancer Institute, Emory University, Atlanta, GA, USA

3 Department of Orthopaedics, School of Medicine, Emory University, Atlanta, GA, USA

\*Address all correspondence to: sakis.mantalaris@gatech.edu

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
