Development of an injectable and bioactive bulking material for the treatment of urinary incontinence, "Beyond the Abstract," by Kyung Min Park

BERKELEY, CA ( - Various biomaterials, which play a role as either passive or active bulking materials, have been utilized to treat urinary incontinence. However, these materials are still insufficient to regenerate the tissues surrounding the urethra (i.e., urethral muscle). In the present study, the authors have developed an injectable hydrogel material that can promote urethral muscle regeneration through sustained release of basic fibroblast growth factor (bFGF). In order to achieve the sustained delivery of bFGF, the authors have tried to incorporate a heparin-based nanogel into the gelatin-based injectable hydrogels. After injection of the hydrogel composite, the bioactive matrices not only supported urethral muscle regeneration, but also played a role as a physical bulking matrix. In addition, the procedure for injection of the composite hydrogel is simple. Furthermore, the hydrogel formula is rapidly solidified when injected into body, which prevents the diffusion of polymer precursor solutions. The unique characteristics of the novel approach enable the hydrogel composite to be an excellent candidate for the clinical use to treat urinary disease as well as a broad range of other regenerative medicine applications.

 bta Kyung-Min-Park fig1
Figure 1. Schematic representation of sequential growth factor delivery systems using macro/nanogel composites. The different growth factors can be encapsulated either into heparin nanogel or into gelatin macrogels, resulting in sequential release behaviors.

In recent years, multiple growth factor delivery systems, which can be designed to deliver growth factors sequentially or in tandem, have received more attention than sustained delivery systems because of their ability to recapitulate biological processes in in vivo microenvironments. Using the macro/nano-gel composite, we can also utilize the systemic growth factor delivery systems that can mimic the in vivo environment. We can incorporate the different growth factors either into the heparin nanogel or into the macrogel matrix. Figure 1 illustrates the sequential delivery system of multiple growth factors using the macro/nanogel composites. For instance, recent studies demonstrated that the sequential delivery of pro-angiogenic factors (i.e., vascular endothelial growth factor, VEGF; angiopoietin-2, ANG-2) and pro-maturation factors (i.e., platelet-derived growth factor, PDGF; and aniopoietin-1, ANG-1) promoted therapeutic angiogenesis.[1] Park and colleagues reported similar approaches. They utilized double-layered core-shell microcapsules for the sequential delivery of VEGF and PDGF, resulting in enhanced angiogenic activity of endothelial cells.[2] Thus, we expect that our macro/nanogel composite may provide advanced therapeutic techniques for a broad range of tissue engineering as well as vascular tissue regeneration.


  1. Brudno, Y., Ennett-Shepard, A. B., Chen, R. R., Aizenberg, M. & Mooney, D. J. Enhancing microvascular formation and vessel maturation through temporal control over multiple pro-angiogenic and pro-maturation factors. Biomaterials 34, 9201-9209, doi:10.1016/j.biomaterials.2013.08.007 (2013).
  2. Choi, D. H., Subbiah, R., Kim, I. H., Han, D. K. & Park, K. Dual Growth Factor Delivery Using Biocompatible Core-Shell Microcapsules for Angiogenesis. Small, doi:10.1002/smll.201300427 (2013).

Written by:
Kyung Min Park as part of Beyond the Abstract on This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

Postdoctoral Research Fellow
Dept. of Chemical & Biomolecular Engineering
Johns Hopkins Physical Sciences-Oncology Center (PSOC), and
The Institute for NanoBioTechnology (INBT)
The Johns Hopkins University
Baltimore, MD USA

Macro/nano-gel composite as an injectable and bioactive bulking material for the treatment of urinary incontinence - Abstract

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