PPTI: Medical Products Based on Unique Biomaterials

PPTI is focused on developing products to improve medical and surgical outcomes, based on an extensive portfolio of proprietary biomaterials. Biomaterials are materials that are used to direct, supplement, or replace the functions of living systems. The interaction between materials and living systems is dynamic. It involves the response of the living system to the materials (e.g., biocompatibility) and the response of the materials to the living system (e.g., degradation). The requirements for performance within this demanding biological environment have been a critical factor in limiting the myriad of possible metal, polymer, and ceramic compositions to a relatively small number that to date have been proven useful in medical devices.

The goal of biomaterials development historically has been to produce inert materials -- materials that elicit little or no response from the living system. However, the Company believes that such conventional biomaterials are constrained by their inability to convey appropriate messages to the cells which surround them -- the same messages that are conveyed by proteins in normal human tissues.

PPTI's Biomaterials Strategy

The products targeted for development by PPTI are based on a new generation of biomaterials which have been designed to be recognized and accepted by human cells, to aid in the natural process of bodily repair (including the healing of tissue and the restoration or augmentation of its form and function), and, ultimately, to promote the regeneration of tissues. The Company believes that the successful realization of these properties will substantially expand the role that artificial devices can play in the prevention and treatment of human disability and disease, and enable the culture of native tissues for successful reimplantation.

Through its proprietary core technology, PPTI produces high molecular weight polymers that can be processed into a variety of material forms such as gels, sponges, films, and fibers, with their physical strength and rate of resorption tailored to each potential product application. These polymers are constructed of the same amino acids as natural proteins found in the body. The Company has demonstrated that its polymers can mimic the biological and chemical functions of natural proteins and peptides, such as the attachment of cells through specific membrane receptors and the ability to participate in enzymatic reactions, thus overcoming a critical limitation of conventional biomaterials. In addition, materials made from PPTI's polymers have demonstrated excellent biocompatibility in a variety of feasibility studies.

PPTI's Biomaterials Technology Platform

PPTI's patented core technology enables messages that direct activities of cells to be precisely formulated and presented in a structured environment similar to what nature has demonstrated to be essential in creating, maintaining and restoring the body's functions. The Company's protein polymers are made by combining the techniques of modern biotechnology and traditional polymer science. The techniques of biotechnology are used to create synthetic genes which direct the biological synthesis of protein polymers in recombinant microorganisms. The methods of traditional polymer science are used to design novel materials for specific product applications by combining the properties of individual "building block" components in polymer form.

In contrast to natural proteins, either isolated from natural sources or produced using traditional genetic engineering techniques, PPTI's technology results in the creation of new proteins with unique properties. PPTI has demonstrated its capability to create materials that:

• combine properties of different proteins found in nature;

• reproduce and amplify selected activities of natural proteins;

• eliminate undesired properties of natural proteins; and

• incorporate synthetic properties via chemical modifications.

Silk-Elastin Polymers

PPTI's primary products under development are based on protein polymers combining selected properties from two of the most extraordinary structural proteins found in nature: silk and elastin.

Silk, based upon its crystalline structure,

has long been known as an incredibly

strong material, and has a long

history of medical use in humans

as a material for sutures.

Elastin fibers are one of the most

remarkable rubber-like materials ever studied.

Found in human tissues such as lungs and

arteries, elastin fibers must expand and contract

over a lifetime, and can be extended

nearly three times their resting length

without damaging their flexibility.

Despite the incredible individual properties of silk and elastin, neither of these natural protein materials is capable of being processed into forms other than what nature has provided without destroying their valuable materials properties. However, PPTI's proprietary technology has enabled the creation of polymers that combine the repeating blocks of amino acids responsible for the strength of silk and the elasticity of elastin. By precisely varying the number and sequence of the different blocks in the assembled protein polymer, new combinations of properties that the Company believes will be of substantial value in developing new medical products have been created.

Additional Protein Polymers

PPTI has also created protein polymers based on repeating blocks of amino acids found in two other classes of structural proteins found in nature: collagen and keratin.

Collagen is the principal structural

component of the body, found in some shape

or form in virtually every tissue, ranging from

shock-absorbing cartilage to light-transmitting

corneas. The defining characteristic of collagen

is a triple-helix structure formed by the

assembly of three identical molecular chains.

Keratin is a major component

of hair, nails and skin.

Its rope-like structure

is based on the alpha helix,

cross-linked into bundles.

The development of materials based on these polymers is at an early stage of research. The Company has also identified numerous additional natural proteins constructed of repeating amino acid sequences that provide a library of "building blocks" for future polymer, materials, and medical product development.