far, most new MPTs have relied only upon chemical barriers (spermicides, antimicrobial agents) to prevent pregnancy and infection, with mixed
relsuts. Promising trials suggest that gels containing tenofovir, an anti-retroviral drug, cut the incidence of HIV by roughly 40%. But, the predominant topical spermicide, N9, causes inflammation of the vaginal mucosa that actually increases risk of HIV infection. Thus far, no
other MPT work as well as condoms.
But a new tampon-shaped microfiber mesh developed at the University of Washington provides both chemical
and physical barriers to pregnancy and HIV. Bioengineers mixed two HIV medications, a Herpes treatment, and a spermicide
into two different polymers that the body safely degrades and absorbs over a few days. The liquified polymers passed through an electric field that drew
them into fibers several hundred nanometers thick, roughly the wavelength of visible light. The fibers collected into a mesh on a mold in the shape of a
The mesh allows for two step release of drugs: one readily dissolves in the vagina and releases its drugs within minutes, while the other emits its
active ingredients over a period of days. By changing the ratio of the two polymers and the fibers' thickness, researchers can "tune" the dosage and speed with which the drugs release. The project's principle investigator, Dr. Kim Woodrow, believes that the polymers could be
used in the future to deliver additional drugs, including prophylaxis against bacterial STIs. An experiment in mice found that the mesh effectively
delivered in vivo a dye analogous to the HIV drugs.
On top of this, experiments demonstrated that in vitro, sperm could not pass through the mesh even when it contained no spermicide. Conceivably,
such a super-thin mesh could be inserted into a woman's vagina and provide barely detectable contraception and HIV protection for a few day period. These
results, recently published in PLos ONE, caught the attention of the Bill and Melinda Gates Foundation and earned a $1 million grant.
Bill and Melinda Gates are not looking for Dr. Woodrow to develop the "condom of the future." Rather, the grant provides money
to continue investigating the versatility and ability of such fiberts to deliver compounds relevant to creating more effective MPTs. Woodrow's mesh
provides a compelling model for how to deliver a slew of drugs and block sperm but significant scientific problems around elasticity, drug delivery, and
kinetics need resolved before researchers can translate this into a commercial product. Between solving these basic research questions and passing clinical
tests for efficacy and safety, a contraceptive made from nanofibers likely remains years away.
Down the road, such a combination of chemical and physical defenses may yield a far superior way of avoiding pregnancy and HIV. While a discreet MPT may
allow more women more control in terms of contraception, such a product cannot solve the greatest challenge for family planning -- ensuring that everyone has access to them.
Despite the low cost of condoms,
222 million women
report that they still do not have sufficient access to contraceptives. These women account for nearly 80% of unintended pregnancies around the world. Until the "condom of
the future" arrives, we should focus on providing everyone access to the reliable old latex.