William Lafayette Mondy

Annual Viral Expression in a Sea Slug Population: Life Cycle Control and Symbiotic Chloroplast Maintenance

In a few well-known cases, animal population dynamics are regulated by cyclical infections of protists, bacteria, or viruses. In most of these cases, the pathogen persists in the environment, where it continues to infect some percentage of successive generations of the host organism. This persistent re-infection causes a long-lived decline, in either population size or cycle, to a level that depends upon pathogen density and infection level (1-4). We have discovered, on the basis of 9 years of observation, an annual viral expression in Elysia chlorotica, an ascoglossan sea slug, that coincides with the yearly, synchronized death of all the adults in the population. This coincidence of viral expression and mass death is ubiquitous, and it occurs in the laboratory as well as in the field. Our evidence also suggests that the viruses do not re-infect subsequent generations from an external pathogen pool, but are endogenous to the slug. We are led, finally, to the hypothesis that the viruses may be involved in the maintenance of symbiotic chloroplasts within the molluscan cells.

Computer-aided design of microvasculature systems for use in vascular scaffold production

In vitro biomedical engineering of intact, functional vascular networks, which include capillary structures, is a prerequisite for adequate vascular scaffold production. Capillary structures are necessary since they provide the elements and compounds for the growth, function and maintenance of 3D tissue structures. Computer-aided modeling of stereolithographic (STL) micro-computer tomographic (micro-CT) 3D models is a technique that enables us to mimic the design of vascular tree systems containing capillary beds, found in tissues. In our first paper (Mondy et al 2009 Tissue Eng. at press), using micro-CT, we studied the possibility of using vascular tissues to produce data capable of aiding the design of vascular tree scaffolding, which would help in the reverse engineering of a complete vascular tree system including capillary bed structures. In this paper, we used STL models of large datasets of computer-aided design (CAD) data of vascular structures which contained capillary structures that mimic those in the dermal layers of rabbit skin. Using CAD software we created from 3D STL models a bio-CAD design for the development of capillary-containing vascular tree scaffolding for skin. This method is designed to enhance a variety of therapeutic protocols including, but not limited to, organ and tissue repair, systemic disease mediation and cell/tissue transplantation therapy. Our successful approach to in vitro vasculogenesis will allow the bioengineering of various other types of 3D tissue structures, and as such greatly expands the potential applications of biomedical engineering technology into the fields of biomedical research and medicine.

Osmium Tetroxide Labeling of (Poly)Methyl Methacrylate Corrosion Casts for Enhancement of Micro-CT Microvascular Imaging

In order to enhance micro-computer tomography (micro-CT) imaging of corrosion casts of fine vasculature, metals can be added to the casting resin before perfusion. However, perfused metals lead to vasoconstriction or vessel damage resulting in nonphysiologic vascular casts. A novel method for coating methyl methacrylate vascular casts with osmium tetroxide has been developed in order to increase micro-CT contrast without affecting the vascular structure. This technique was verified using corrosion casts of the lung vasculature of New Zealand white rabbits. Osmium tetroxide coating of methyl methacrylate vascular corrosion casts resulted in an increase in overall sample contrast that translated into an increase in the resolution of the vasculature. This method can therefore lead to increased resolution in the characterization of fine vascular structures.

The Basement Membrane: Key to the Reverse Engineering Biological Tissues

We reveal the basement membrane, a specialized connective tissue structure found in all tissue systems, as a framework in an adaptive computer aided design (CAD) strategy for the reverse engineering of 3 dimensional (3D) tissue structures. Our approach to the creation of functional 3D tissue structures is centered on our previous models of vascular supply systems which included complete and accurate replications of capillary bed systems, the circulatory interface necessary to sustain 3D tissue structures. By using the basement membrane as a guide, we seek to design models for the reverse engineering of the other extracellular connective tissue structures and their matrix elements. We demonstrate the basement membrane as a platform for the design and engineering of tissue scaffolding for vascularized alveolar systems in the lung and for the vascularized dermal skin layer. The resulting structure will support the 3D growth and differentiation of cells and their products. The biomedical industry stands to be greatly impacted by this CAD approach to the engineering of 3D tissue structures.