PuraMatrix™ Technology
Our scientific founders have pioneered the related fields of self-assembling peptides, collagen structure, tissue engineering, biodegradable biomaterials, controlled drug delivery, 3-D cell culture, and cellular biology. The technology underpinning 3DM's next generation biomaterials--a synthetic, in situ self-assembling, amino-acid based, three-dimensional hydrogel scaffold--is exclusively licensed from the Massachusetts Institute of Technology, where it has undergone over a decade of research and publication. In 2005, the NIH granted our scientific founders at MIT a multi-year $6.5M program grant for Functionalized Self-Assembling Peptides in Regenerative Medicine.
PuraMatrix™ can be used as a scaffold for cell-attachment to encapsulate cells in 3-D, plate cells in 2-D coatings, or cell culture microcarriers in suspension cultures. (Flash movie) A number of these cell types have not been able to be grown properly outside of the body, heretofore uncultivable, or have required materials which are frowned upon because they introduce undefined variables, inconsistency and foreign materials to the research experiment or clinical therapy. PuraMatrix is forward compatible with in vivo implant studies, for use as an injectable soft tissue matrix fill, drug and therapeutic stem cell carrier, and medical device implant coating. PuraMatrix versions are available for clinical therapeutic and bioproduction cGMP requirements.
Clinical & Technological Advantages:
- Benefits of 3D in vitro cell culture & cell structures with the ease of 2D plating
- Enables accelerated healing/regeneration – quicker resorption in vivo while allowing tissue ingrowth
- Nanofiber self-assembly –1st synthetic nano-scale scaffolds able to replace native ECM
- Biocompatible & non-immunogenic – low concentration (1-3%) of amino acids in water
- Synthetic origin – solves reproducibility, sterility, disease risk and regulatory concerns
- Radiolucent – allows noninvasive radiographic measurement of bone regeneration
- Compatible & easily combined with surgical tools, implants, therapeutics
- Bioactive customization – add bioactive motifs for specific biological response
- Regulated as medical device – structural scaffold, clean tox & biocompatability
- Intellectual property – strong granted patents enable patent work-around for combination products
3-Dimensional Cell Culture Matrices
Given the growing body of literature, drug discovery efforts at major pharmaceutical and biotechnology companies are beginning to adopt 3-D culture techniques in their cell-based assays, especially in the context of Drug Screening, Toxicology Assays, High Content Screening, and Bioproduction.
Using products like PuraMatrix™, in order to create synthetic extracellular matrix (ECM) scaffolds and tuned 3-D microenvironments, has proven to yield better data while also reducing the number of animals used for expensive in vivo testing. The National Cancer Institute's US$40 million new program on the cellular micro-environment will spur research and adoption of 3-D culture techniques and products in both academia and industry.
Until recently, 3-D cell culture has required either animal-derived materials, with their inherent reproducibility and cell signaling issues, or much larger synthetic scaffolds, which fail to approximate the physical nanometer-scale and chemical attributes of native ECM. PuraMatrix™'s nanometer-sized fibers, very difficult and expensive to create without 3DM's patented molecular self-assembly, provides a scaffold encapsulating cells in 3 dimensions and allowing defined cell culture conditions, cell migration, nutrient diffusion, and cell harvesting.
For the first time, the cell biology and drug discovery communities now have a biocompatible bare matrix scaffold which can be combined with relevant proteins and growth factors to more closely resemble the in vivo milieu, and which is forward compatible with cGMP requirements for cell therapy, medical device and bioproduction applications. The PuraMatrix™ gels have undergone extensive in vivo toxicology safety testing.
ECM, Microenvironments, and 3-D Culture
The extracellular matrix (ECM) is a vital component of cellular microenvironments, providing cells and tissues the appropriate 3-D architecture for normal growth and development.
Most cell culture and cell signaling research has used two-dimensional constructs to study single cell populations treated selectively with soluble factors in a homogeneous environment (Sipe, NIH, 2002). This greatly simplifies the research models, but also mitigates the powerful effects of ECM and 3-D culture conditions on the cells of interest.
Many studies have demonstrated that the ECM promotes key signaling pathways, influencing and enabling cell proliferation, differentiation, and proper cell-cell and cell-tissue interactions. Recreating these conditions and structures in vitro, rather than growing cells in 2-D petri dishes and flasks, has yielded tools for more rapid and accurate biological analyses (Geiger et al., 2001). Moreover, fields of tissue engineering, stem cell biology, and cancer biology are realizing that ECM and a tuned three-dimensional microenvironment are critical for the proper understanding required for any successful clinically-relevant therapies.
SAPS not only provide the 3-D context for research, but they also fulfill the more stringent bioproduction and clinical requirements necessary for eventual therapies (see PuraMatrix™ Comparison Table).
3DM's patent portfolio consists of 5 granted patents (numerous filings in process worldwide, dominated by US5670483).
Peptide Hydrogel Scaffolds Overview
Over the past ten years, a new class of biologically-inspired polypeptide biomaterials has been discovered and tested in the context of cell culture, stem cell biology and tissue engineering.
These peptide hydrogel scaffolds, which we call PuraMatrix™, have been used successfully as a synthetic in vitro and in vivo ECM, proving themselves as a critical component to successful 3-D cell growth.
PuraMatrix™ is synthesized in small (16 amino acids long, 5 nanometers) oligopeptide fragments that self-assemble into nanofibers on a scale similar to the in vivo extracellular matrix (ECM).
The physical size relative to cells and proteins, and the amphiphilic peptides' impressive water-structuring abilities mimic in vivo ECM, allowing cells to proliferate, migrate through, and engage in critical cell-cell interactions in the presence of key regulatory molecules.
These fine nanofibers create a 3-dimensional porous scaffold that is very difficult or impossible to synthetically produce by other manufacturing techniques.The fiber density and average pore size correlates with the concentration of peptide solution that is used to produce the material, which can be varied from 0.02 to 3% in water (5-10mg/ml w/v) depending on the application and thickness of gel required.
The material consists of amphiphilic peptides that have alternating repeating units of positively-charged lysine or arginine and negatively-charged aspartate and glutamate residues. These peptides contain 50% charged residues and are characterized by their periodic repeats of alternating ionic hydrophilic and hydrophobic amino acids; thus, the interaction between the distinct polar and non-polar surfaces facilitates self-assembly of the material into a nanofiber hydrogel scaffold which can coat surfaces or encapsulate cells as a 3-D weak gel (Zhang, et al., 1995; Holmes, et al., 2000; Kisiday, et al., 2002).
Hence, PuraMatrix™ mimics important physical and chemical aspects of the in vivo microenvironment - a provisional synthetic matrix ECM - while eliminating complicating variables such as those from animal-derived materials such as collagen, fibronectin, mouse sarcoma ECM, and cadaver tissue.
Unlike most other materials, PuraMatrix™ can be sterilized through UV radiation or filtration, and has proven itself shelf-stable at room temperature for up to 18 months, lowering the processing, transportation, and inventory costs.
Clinical Quality and Compatibility
PuraMatrix™ is synthetic and sterile, hence suitable for bioproduction and can be readily used in the clinic, unlike many animal derived materials (bovine or otherwise) that lack the consistent quality control, thus complicating clinical reproducibility and risking the introduction of undesirable contaminants (cell signaling motifs, adventitious agents, etc.).
PuraMatrix™ is manufactured in large scale quantities, using processes which are compatible with medical-grade quality standards. Additionally, PuraMatrix™ can be used for closed, sterile system culture in vitro and can also be injected in vivo without causing the immunoresponsive events that materials such as collagens and alginates can illicit.
The past two decades have witnessed the quest for biocompatible, resorbable and effective scaffold materials for cell culture, tissue engineering and in vivo use. Synthetic macroporous scaffolds, such as PLA and PLGA biodegradable polymers, have seen limited success due to either their large scaffold size relative to cells, acidic breakdown products, charge density, or inability to allow the creation of true microcellular environments (Langer, 1996).
On the other hand, animal-derived products such as bovine collagen, intestinal submucosa, cadaver tissue, basement membrane ECM, and mouse sarcoma extract may not provide the appropriate signaling that is required by the clinician. Also, these materials may be immunogenic and complicate clinical therapies without strict quality control. These risks are amplified in cancer patients with suppressed immune systems.
Hence, PuraMatrix™ fulfills the best of both groupings of traditional biomaterials:
- the stringent bioproduction requirements that will be required for therapeutic applications through its synthetic composition, free of the signaling motifs, adventitious agents in animal product, and
- a nanoporous/nanofiber gel to enable proper 3-D cell growth and the creation of microenvironments surrounding cell colonies.
Moreover, PuraMatrix™ can be sterilized in situ and has proven itself shelf-stable at room temperature for up to three years.
Comparison of PuraMatrix™ to Other Scaffolds