DOW-UAP-D119: Biomaterials - A Medical Survey from Silicone Implants to Dialysis Membranes

Source file: DOW-UAP-D119_AAWSAP-DIRD-Biomaterials-January-7-2010.pdf Originating agency: Defense Intelligence Agency (DIA), Defense Warning Office, under the AAWSA Program Document type: Defense Intelligence Reference Document (DIRD), "Acquisition Threat Support" series; control number DIA-08-0912-006 Date: 7 January 2010 (information cutoff date, ICOD: 1 December 2009) Classification: UNCLASSIFIED//FOR OFFICIAL USE ONLY, with the FOUO caveat struck through on every page; released 2026 Page count: 32 VIRIN: 260918-D-D0360-1108 PURSUE Release: 6

Summary

"Biomaterials" is a Defense Intelligence Reference Document dated 7 January 2010, with an information cutoff date of 1 December 2009, prepared by the Acquisition Support Division (DWO-3) of the DIA's Defense Warning Office, Directorate for Analysis. The author is redacted as "AAP Person 65." The administrative note is the series' standard text: "one in a series of advanced technology reports produced in FY 2009" under the AAWSA Program, with questions to AAP Person 1, the AAWSA Program Manager, at a DIA address in Washington, and a warning that further dissemination of the photographs is not authorized.

After an introduction with two short subsections ("Importance of Biocompatibility" and "Science of Biomaterials"), the paper runs through some twenty topical sections, from biosensors and silicones to titanium implants and dialysis, and ends with a two-paragraph "Summary and Recommendations." It is heavily illustrated, with 31 figures, many of them product photographs and marketing images, and, unlike its sister papers DOW-UAP-D117 and DOW-UAP-D118, it contains no references or endnotes at all.

The paper does not mention UFOs or UAP. More strikingly, it never mentions aircraft, spaceflight, pilots or military applications either. Its only phrase that points beyond civilian medicine is a note that biosensors monitor tissues "for medical therapeutics or for assessing human performance" (page 8). If it serves any of the technical areas in the program's Statement of Objectives (DOW-UAP-D110), it would be human effects, the human interface or the catch-all of supporting topics, but the paper itself draws no such connection.

Research Article

Definitions and the biocompatibility problem

The paper opens with a definition: "Biomaterials are metals, ceramics, polymers, glasses, carbons, and composite materials intended to interface with biological systems" (page 5). They are usually nonliving, although "recent definitions also include living skin and tissues produced in culture." The author separates biocompatible materials of synthetic origin (artificial hips, stents, pacemakers, catheters) from biological materials such as bone, and from biomimetic ones, such as the calcium hydroxyapatite coating on artificial hips, which resembles the coating of mollusk shells. The uses listed go well beyond implants: cell culture, blood-protein assays, fertility-regulation implants in cattle, diagnostic gene arrays, the aquaculture of oysters and "cell-silicon 'biochips'" (page 6).

Figure 2 conveys the scale of the field with worldwide annual device counts: 300,000,000 catheters, 75,000,000 contact lenses, 25,000,000 renal dialyzers, 7,000,000 intraocular lenses, more than 2,000,000 cardiovascular stents, 1,000,000 hip and knee prostheses, 500,000 dental implants, 400,000 vascular grafts, 300,000 breast implants, 200,000 heart valves, 200,000 pacemakers and 100,000 left ventricular assist devices, under the caption "Millions of lives saved. The quality of life improved for millions more. A $100 billion industry" (page 7). No source is given for these figures.

The central problem is biofouling. Once a device is implanted, its surface becomes coated with proteins, blood-formed elements, immune cells and sometimes scar tissue, a foreign-body reaction that isolates it from the body. For implanted sensors the record is bleak: in "more than 600 reported studies since 1996" results have been so poor "that many companies have abandoned implantable sensor devices altogether," and the trend is toward optical sensors placed outside the body (page 6). The paper also notes that biomaterials usually face "the same very stringent safety requirements as those of new drug therapies" (page 7), a point it returns to in its conclusion.

Biosensors: the hardest job

Implantable biosensors, which monitor glucose, oxygen, blood pH, adrenal hormones, nervous activity, heart performance or blood pressure, "place some of the greatest functional demands on biomaterials." A heart valve can tolerate a low-level foreign-body reaction, but the same reaction can render a blood-glucose sensor "useless after a few days" (page 8). Protective membranes let small molecules through while excluding proteins and cells such as macrophages, but "No one biomaterial is best for all sensor applications": a membrane that passes glucose may not pass the oxygen the sensor needs. The bloodstream is "the most hostile location," both for sensor performance and because of the risk of clotting. The most successful membrane materials have been porous Teflon, polyurethanes and cellulose acetate (page 9).

Polymers: silicone, Teflon, biodegradables and hydrogels

The paper lists seven of the best-known biomaterials (silicone, Teflon, biodegradable polymers, hydrogels, titanium alloys, ceramics and tissue constructs) and five of the largest applications (cardiovascular devices, hip and knee joints, contact lenses, drug delivery and kidney dialysis) (page 9). Silicone, chemically polydimethylsiloxane (PDMS) and "often mistakenly called 'silicon,'" is blood compatible, sterilizable and tunable in hardness. The paper recalls the 1995 class-action settlement against Dow Corning over breast implants and quotes the Institute of Medicine's finding that connective-tissue disease, cancer and neurological disease "are no more common in women with breast implants than in women without implants"; Dow, it says, left the medical silicone business (page 10). Silicone's gas permeability makes it standard for oxygen and carbon-dioxide sensor membranes, and it appears in tracheostomy tubes and in Mepiform sheets for keloid scars (pages 11-12).

Teflon (PTFE) is inert and slippery thanks to its strong carbon-fluorine bonds; its expanded form, ePTFE or Gore-Tex, is porous enough for tissue ingrowth and is used in vascular grafts and lip implants. Yet PTFE sheds wear particles under compression or abrasion, and "applying it in the wrong circumstances" can produce a reaction "that no longer qualifies as 'biocompatible'" (page 14). Biodegradable polymers degrade in two steps, hydrolysis into shorter chains and then enzymatic attack, ending in "bulk erosion," the mechanism of "All the commercially available synthetic devices and sutures" (page 15). The paper's clearest clinical argument comes here: a rigid stainless-steel bone plate shields the healing bone from load, so the bone tends to refracture when the plate is removed, whereas a degradable fixation can transfer load gradually and never needs removal. Polylactide (PLA), made from corn starch in the United States or sugarcane elsewhere, appears in sutures, screws, dental membranes and drug microspheres; a PLA sheet placed over the heart after open-heart surgery stays for "a week or so" and then dissolves (pages 16-17). Polyethylene glycol creates "nonfouling" surfaces, and hydrogels such as poly(HEMA), with water content "of up to 90 percent," serve in drug release, artificial tendons, wound adhesives, artificial skin and contact lenses (pages 17-18).

Metals and ceramics

Titanium hip implants "often show no visible sign of their existence" and "In adults, they can last a lifetime" (page 18). Bioceramics range from inert oxides to resorbable materials that the body eventually replaces. Alumina has served as the joint surface of total hip prostheses "for more than 20 years" because of its very low friction and wear; hydroxyapatite, processed into a porous "bone-like" structure, is used in vertebral prostheses, middle-ear bones and jaw repair; and coral skeletons can be converted into hydroxyapatite by heat (page 19). Dental porcelains can be harder than natural enamel but more brittle, and zirconium oxide, with a three-point bending strength "exceeding 900 megapascals," is presented as a coming material for bridges and implant superstructures, shaped with CAD/CAM molds (page 20).

A later section returns to titanium (pages 29-31). Its thin, adherent oxide film, titania, is credited with its tolerance in warm, salty body fluids, and "Essentially all pacemakers, neurostimulators, and various other implanted medical devices" use it as a case material. The paper tells the story of osseointegration: in 1952 the Swedish professor Per-Ingvar Brånemark fixed living rabbit bone in a titanium holder and found after many days that the two had fused so completely that removal was impossible; "He called this osseointegration and saw the possibilities for human use" (page 29). It then lists surface treatments (sandblasting, plasma etching, acid pitting and, as of 2008, laser-melted pits), hydroxyapatite coatings about 1 micron thick, spherical hydroxyapatite nanopowder, and silane treatments that attract proteoglycans and collagen, and it prefers the alloy Ti-6Al-4V over cobalt-chromium for coated implants because of lower stress shielding (pages 30-31).

Tissue, blood, eyes and drugs

Tissue engineering, the author writes, "is a bit of a misnomer," since it is really advanced cell culture (page 20). Cells and signaling molecules are seeded into porous biodegradable scaffolds shaped like the missing bone or tissue (Figure 19), and "Perhaps the biggest challenge" is growing blood vessels in time, since without a blood supply "cells will die, and mass infection will occur" (page 21). Scaffolds built by computer-driven, ink-jet-like deposition can produce simple structures such as the cartilage of an ear lost in an accident, but not complex organs like a heart or kidney (page 22).

Blood contact is the most demanding setting. Figure 21 lists contact times, from minutes-to-hours for guidewires to "lifetime" for vascular grafts, heart valves and stents (page 23). Materials in blood tend to trigger thrombus, which can break loose and cause a stroke or embolism; small grafts under 5 millimeters in internal diameter are "'safe' only when anticoagulant drugs are used," and implants colonized by antibiotic-resistant bacteria such as MRSA may have to be removed before an infection can be resolved (page 24). The paper describes Gore's Teflon vascular grafts and atrial-septal-defect patches for infants, a stainless-steel and Teflon Björk-Shiley valve, balloon-expanded stainless-steel stents and self-expanding nitinol stents, held collapsed by cold saline and opened by body heat through the shape-memory effect (pages 23-26). Contact lenses get a short history, crediting modern soft lenses to the Czech chemist Otto Wichterle and his assistant Drahoslav Lím, followed by PMMA, rigid gas-permeable lenses made by adding silicone to acrylics, and silicone hydrogels launched in 1999 (pages 26-27). Drug-delivery polymers, driven largely by the need for slow insulin release in brittle diabetes, offer localized delivery, sustained release and drug stabilization; the standard polymers PLA and PLGA have been used "for more than 20 years" (pages 27-29).

Dialysis and the paper's conclusion

The final technical section explains hemodialysis: blood drawn through two large needles flows through thousands of hollow fibers while waste diffuses out. "The design of dialyzers is primarily an exercise in biomaterial selection," the author writes, naming Cuprophane as the most common membrane. High-flux membranes aim to pass beta-2-microglobulin (11,600 daltons) but not albumin (about 66,400 daltons), and dialysis keeps "millions of people" alive, usually for several hours three to four times a week (pages 31-32).

The "Summary and Recommendations" section, despite its title, makes no recommendations. It argues that because biomaterials "often serve critical, perhaps life-and-death, functions" they require large amounts of money and time to test, and that "This appears to be the reason the biomedical industry is slow to produce and accept new materials." Existing implant materials have generally been available for more than 20 years, and "most of the innovation is occurring in devising new ways to embody the materials and apply them to new applications" (page 32).

What the paper does not contain

The contrast with its sister documents is sharp. DOW-UAP-D117 (metallic glasses) and DOW-UAP-D118 (programmable matter), dated about three weeks earlier, both frame their subjects around aerospace and offer explicit horizons (20-50 years; 2050). This paper offers no timeline, no forecast, no assessment of foreign research and no application outside civilian medicine. It cites no sources, so its statistics, including the device counts and the "600 reported studies," cannot be traced from the document itself, and many of its illustrations are manufacturer materials (the ePTFE lip-implant before-and-after images, a Polysciences advertisement, a PLA barrier graphic with the slogan "The Clear Choice," Gore products).

There are also editorial slips. From Figure 25 onward the captions no longer match the list of figures or the text: two figures are captioned 25 and two 26, the contact lens appears as Figure 25 but is cited as Figure 27, and the Cuprophane membrane is captioned Figure 29 but cited as Figure 31. A scaffold polymer is called CSLA in the text and CSLG in its caption, and the dialysis text and its figure disagree on the color of the dots. Two technical statements also differ from standard accounts: the paper calls PLA short-lived (days) and PGA longer-lived (months), whereas PGA is usually described as the faster-degrading of the two, and its contact-lens history places PMMA after the soft lens, although rigid PMMA lenses came first.

Significance

For the archive, the paper's main value is as evidence of how far AAWSAP's reference series ranged. The official description warns that "not every DIRD in the series directly concerns aerospace systems or future threat assessment"; this is the clearest case among the early DIRDs. The document gives no reason why a general medical primer on implants, stents and contact lenses was produced under an advanced aerospace weapons program. The program's Statement of Objectives does include human effects and the human interface, and the paper's single mention of "assessing human performance" is the only thread in that direction, but any connection is an inference the document does not make.

On its own terms, the paper is a competent, textbook-level overview of the biomaterials field as it stood around 2009, and its central judgment, that safety testing keeps medicine tied to established materials such as silicone, Teflon, biodegradable polyesters, ceramics and titanium, is plausible and plainly argued. Its lack of sources, its commercial imagery and its editorial errors limit its usefulness as a reference, and it contains nothing about UAP.

Key People

Locations

Key Concepts

Notable Quotes

"Experiences of many investigators (more than 600 reported studies since 1996) with the biocompatibility of biomaterials related to the function of implanted biosensors have been poor such that many companies have abandoned implantable sensor devices altogether." -- page 6

"Because of this, biomaterials are usually subjected to the same very stringent safety requirements as those of new drug therapies." -- page 7

"These types of responses are not specifically important to implantable devices that have structural rather than sensing functions, such as heart valves, but they can completely render a biosensor for blood glucose, for example, useless after a few days." -- page 8

"No one biomaterial is best for all sensor applications, primarily because different biomaterials behave differently relative to the substance being sensed." -- page 8

"This is a bit of a misnomer in that it is an advanced form of cell culture and cellular biology and has little in common with engineering in the classical sense of application of mathematics and physics to problems." -- page 20

"Perhaps the biggest challenge for tissue engineering is how to ensure angiogenesis in a timely fashion within the scaffold construct; without a blood supply, cells will die, and mass infection will occur." -- page 21

"The design of dialyzers is primarily an exercise in biomaterial selection." -- page 32

"Existing materials for implants are generally based on materials that have been available for more than 20 years. Biodegradable materials, particularly the polylactide and glycolide, have a long history of safe and effective use. Building on this solid foundation, most of the innovation is occurring in devising new ways to embody the materials and apply them to new applications." -- page 32