Regenerative medicine (RM) holds the potential to address some of society’s most intractable health problems and restore or establish normal bodily function. Today, regenerative medicine is an emerging technology that relies on the convergence of a number of competencies in biotechnology and bioengineering. By merging these collective competencies, researchers hope to provide the critical answers to the complex problems of tissue engineering and extend these concepts into regenerative medicine.

Fig. 1 – A double wall resorbable PGA braided textile scaffold allows for design control to simulate the 3D luminal architecture of organs to support regenerative medicine.
Advanced high definition 3D textile architecture (HD3DTA) employed in the creation of luminal scaffold constructs is one example in which regenerative medicine has enjoyed the convergence of strategic technologies and resources. A significant proof point is the pairing of biomedical textile engineering with innovative fiber biomaterials in tissue scaffold development. These luminal structures with 3D functional mechanical architectures can enable the engineering of hollow- bodied constructs for numerous hollow organ regenerative applications.

Endogenous Recruitment

Innovation has advanced RM. Innovation by its simplest definition is “something that has impact.” The field of tissue regeneration and reconstruction is based on three major and innovative technologies: (1) stem cell technology, (2) growth factor technology, and (3) biomaterial technology.

Biomaterials have made a significant impact in RM not only through implantable and biodegradable medical textiles, but also in the 3D architectural and bioengineering approach to organ scaffold design. Advanced biomaterials will eventually transform such traditional textile engineering activities into the next generation of therapeutic applications.

Tissue engineers have faced a number of RM challenges. One of the great puzzles in tissue engineering and regenerative therapies revolves around the persistent belief that eventually biotechnology would discover the switch to turn on or turn off the necessary cell processes that would allow the transplantation of healthy in vitro cultured tissues. The puzzle lies in the fact that in vitro success has not yet fully translated to in vivo success. Now, the prevailing mentality centers on encouraging endogenous (in vivo) cellular mechanisms to bring about the body’s natural self-healing process. This activity is termed “endogenous recruitment.”

Progenitor or healing stem cells specifically destined for the repair and regeneration process circulate throughout the human bloodstream. Many of these healing stem cells reside quietly, waiting in niches associating with specific organ tissues. Endogenous recruitment requires that the micro- and macro-architectural designs of endogenous tissue scaffolds provide functional mechanical properties for these cells to proliferate in a simulated organ-like matrix. These matrices must experience mechanical properties and native forces associated with the natural molecular and cellular processes within the functional organ system in order to prompt cells to naturally populate the scaffold or to encourage endogenous recruitment of the body’s regenerative cells with the help of growth and trophic agents. The engineer merely provides the appropriate stage for this tissue regeneration to play out.

Impact of Convergent Technologies

Fig. 2 – Warp knit scaffold provides high surface area for tissue engineering.
Synthetic biomedical textiles have long enjoyed an important role in implantable vascular graft technology. The basic constructs familiar in synthetic textile repair can now be confidently transformed into biodegradable tissue scaffolds by changing the building block materials of construction. The impact of coupling new biomaterials with precision textile engineering allows the tissue engineer the ability to control multiple functional tissue mechanical properties of the biodegradable with “rational,” or modifiable, scaffold design. This technology presents a number of innovative approaches to scaffold performance in situ. Hollow organ architecture in scaffold design using Secant Medical® highdefinition 3D luminal constructs offers a number of applications, among the most obvious being vascular tissue engineered scaffolds.

The vascular scaffold is analogous to the 3D support matrix-architecture into and onto which organ cells regenerate into the tissues of importance. A key distinction between grafts and scaffolds is that the scaffold is deliberately intended to be a temporary structure and is designed to be resorbed by the body over time as the scaffold is populated by the organ tissue. Resorption supports tissue remodeling. In contrast, vascular grafts are permanent implant devices. In the simplest terms, the graft is a foreign body. Unfortunately, over time, scientists have learned that graft implants have limited ability to replicate biology. This limitation is the driving force behind endogenous recruitment. Material advances now allow more reliable bio-inspired structures to be designed to support tissue regeneration.

Medical Design Briefs Magazine

This article first appeared in the August, 2012 issue of Medical Design Briefs Magazine.

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