Scientists and entrepreneurs who contemplate developing nanomedicine products face several unique challenges in addition to many of the traditional hurdles of product development. In this review we analyze the major physicochemical, biologic and functional characteristics of several nanomedicine products on the market and explore the question of what made them unique. What made them successful? We also focus on the regulatory challenges faced by nanomedicine product developers. Based on these analyses, we propose the factors that are most likely to contribute to the success of nanomedicine products.

Young, and mid size biotech companies can benefit hugely from the US National Institutes of Health (NIH), not least because of the agency's non-dilutive funding, guidance, and opportunities for collaboration. Increasingly, however, there is a fair bit of misunderstanding about what the NIH can and cannot do for a biotech entrepreneur.

After a heart attack, patients often undergo a procedure to open up the clogged artery and install a tiny meshlike device called a stent to keep the artery propped open. In most cases, the body reacts to this foreign object with scar-tissue formation, and the artery narrows again. To combat this re-clogging process, National Institutes of Health inventors developed paclitaxel-coated stents and later licensed it to Angiotech. Approved by the Food and Drug Administration in March 2004, these stents are expected to substantially reduce the use of coronary artery bypass surgery, an expensive operation now performed annually on 350,000-plus Americans. This and three other examples of NIH licensing success stories are described in this paper: (a) Kepivance, which improves the quality of life for cancer patients by eliminating mouth sores, (b) AIDS drug ddI, an important component of many combination drug therapies, and (c) Vitravene, the first and only antisense drug to be approved by FDA. These four examples will illustrate the success not only of the NIH licensing program, but also the innovative approaches taken by NIH inventors and the persistence of its commercial partners. This paper also highlights the business and legal lessons learned from these four cases.

Certain yeasts cause large-scale spoilage of preserved food materials, partly as a result of their ability to grow in the presence of the preservatives allowed in food and beverage preservation. This study used robotic methods to screen the collection of Saccharomyces cerevisiae gene deletion mutants for both increased sensitivity and increased resistance to sorbic acid, one of the most widely-used weak organic acid preservatives. In this way it sought to identify the non-essential, non-redundant activities that influence this resistance, activities that might be the potential targets of new preservation strategies. 237 mutants were identified as incapable of growth at pH 4.5 in presence of 2 mM sorbic acid, while 34 mutants exhibit even higher sorbate resistance than the wild-type parental strain. A number of oxidative stress-sensitive mutants, also mitochondrial mutants, are sorbate-sensitive. This appears to reflect the importance of sustaining a reducing intracellular environment (high reduced glutathione levels and NADH/NAD and NADPH/NADP ratios). Sorbate resistance is also very severely compromised in mutants lacking an acidified vacuole, in vacuolar protein sorting (vps) mutants, in mutants defective in ergosterol biosynthesis (erg mutants) and with several defects in actin and microtubule organization. Sorbate resistance is, however, elevated with the loss of the Yap5 transcription factor; with single losses of two B-type cyclins (Clb3p, Clb5p); and with loss of a plasma membrane calcium channel activated by endoplasmic reticulum stress (Cch1p/Mid1p).

A simple and rapid method for preparing plasma membranes from isolated cells or tissues is described. The membranes were characterised (a) biochemically by an analysis of specific marker enzymes, (b) by quantitation of cell surface receptors, and (c) immunologically by their ability to elicit specific allogeneic responses from cytotoxic T cells in secondary in vitro stimulations. Based on both biochemical and immunologic criteria, plasma membranes prepared by the method described here are of equal or greater 'purity' compared to those prepared by two other methods that are most widely used to date and the yields are several-fold higher.

Successful transplantation of cell surface molecules from the membranes of one cell type to recipient cells of a different type is described. Plasma membranes purified from donor cells were fluoresceinated and fused to recipient cells using poly(ethylene glycol) and the fate of the transplanted membrane components was followed by fluorescence microscopy. In approximately 100 min the 'foreign' membrane components were seen to cluster and internalise. During this time, judged by the criteria of hormonal stimulation and immune cytotoxic killing, the cell surface of the recipient cell mimicked the cell surface phenotype of the donor cell.

The isolation and characterization of a hybridoma cell line producing a monoclonal IgG1 antibody against a spin-label nitroxide group is described. The antibody recognizes a synthetic hapten containing linked dinitrophenyl and 2,2,6,6-tetramethylpiperidinyl 1-oxy groups, having an affinity of 3.6±1.0·106 M−1 for the soluble hapten at 25°C. The antibody binds to phospholipid vesicles containing 2 mol% of spin label-derivitized lipid (lipid hapten) with an affinity of 1.5±0.2·108 M−1. This monoclonal IgG1 mediates the binding of hapten-bearing lipid vesicles to mouse macrophage RAW264 cells bearing Fc receptors. The cellular responses to this binding are similar to those observed previously using polyclonal rabbit anti-hapten IgG. As with the heterogeneous antibodies, the monoclonal IgG1 is more efficient in mediating cellular uptake when the vesicles are in the ‘fluid’ physical state (dimyristoylphosphatidylcholine at 37°C) compared to ‘solid’ (dipalmitoylphosphatidylcholine at 37°C). Despite the enhanced binding of ‘fluid’ phospholipid vesicles to cells, only the ‘solid’ vesicles triggered a significant respiratory burst in RAW264 macrophages.

We have studied the binding of liposomes containing dinitrophenylated lipid to rat basophil leukemia cells armed with monoclonal anti-dinitrophenyl IgE. The liposomes were either "fluid" at 37 degrees C (dimyristoylphosphatidylcholine or an equimolar binary mixture dipalmitoylphosphatidylcholine and cholesterol) or "solid" (dipalmitoylphosphatidylcholine, distearoylphosphatidylcholine, or dibehanoylphosphatidylcholine). We have also studied the immune mediated degranulation of these cells induced by the above lipid membrane targets. In some cases both studies were carried out with liposomes containing various surface densities of lipid haptens. From these studies we conclude that freely mobile nonaggregated lipid haptens in bilayer membrane targets can trigger efficient serotonin release from rat basophil leukemia cells in the presence of specific antihapten IgE. Solid target membranes are also effective as stimulators of serotonin release. The release of serotonin depends strongly on the surface density of lipid haptens over a narrow range of surface densities. These studies with lipid membrane targets having well defined physical properties indicate the need for generalized molecular models of receptor-mediated cell triggering.

We have included a lipid hapten in lipid monolayers coated on alkylated quartz microscope slides to serve as specific antibody-dependent targets for rat basophil leukemia cells.At room temperature basophils armed with specific monoclonal IgE antibodies adhere tightly to the monolayer only when the monolayers contain lipid hapten and only in the presence of Mg2+ and/or Ca2+.The basophils undergo specific IgE-and haptendependent immunologic degranulation under these conditions.Fluoresceinated IgE antibodies bound to Fc receptors on the basophil and located within -100 nm of the monolayer target fluoresce when excited by laser radiation undergoing total internal reflection within the quartz slide.An optical interference pattern produced by two focused intersecting coherent laser beams having total internal reflection within the quartz slide serves as a control to ensure that all of the emitted fluorescence radiation from the IgE molecules is due t o stimulation by evanescent radiation and not by scattered radiation.The interference pattern is also used for pattern photobleaching experiments to determine the rates of lateral diffusion of IgE molecules bound to the monolayers, in the absence of cells.Specific antibody-dependent adherence of basophils to the monolayer target results in a marked enhancement of IgE fluorescence in the field of the evanescent wave.Microscopic examination of the fluorescence of the fluoresceinated IgE molecules in the region of basophil membrane-monolayer membrane contact reveals an extremely complex pattern, presumably due to cellular filopodia-like structures that are anchored t o the target membrane via IgE molecules bound simultaneously to Fc receptors and lipid haptens.These structures are not observable with conventional epifluorescence microscopy due t o the fluorescence of IgE molecules bound to the basophils in regions other than the interface between the monolayer and basophil membranes.The concentration of IgE molecules in the contact region appears to be high and could give rise to Fc-Fc receptor complex formation or other redistributions of Fc receptors that provide signals for basophil degranulation.

We have measured the binding of two radioiodinated monoclonal anti-dinitrophenyl antibodies (IgE and IgG2a) to two dinitrophenylated lipid haptens in lipid bilayer membranes having various compositions and physical properties. These antibodies bind strongly to the lipophilic dinitrophenyl group in some membranes. Dimyristoylphosphatidylcholine and dipentadecanoylphosphatidylcholine containing 2 mol % dinitrophenyl lipid hapten bind anti-dinitrophenyl antibodies below the chain-melting transition temperatures of these lipids (22 and 35 degrees C, respectively) but not above these temperatures. Evidently, the lipophilic dinitrophenyl group is partially or completely buried in the hydrophobic region of these bilayers at temperatures above the chain-melting transition temperatures. The inclusion of increasing concentrations of cholesterol in such membranes (e.g. in dimyristoylphosphatidylcholine at 37 degrees C) results in a marked enhancement of antibody binding. It was found that a third lipid hapten containing the dinitrophenyl group does not show this strong dependence of antibody binding on the physical state of the lipid membrane. The weak immunologic degranulation of rat basophil leukemia cells by dimyristoylphosphatidylcholine membrane targets at 37 degrees C can be attributed to a weak binding of anti-dinitrophenyl IgE to these membranes (Balakrishnan, K., Hsu, F. J., Cooper, A. D., and McConnell, H. M. (1982) J. Biol. Chem. 257, 6427-6433). However, if the antibody is first allowed to bind to this membrane below the lipid chain-melting transition temperature, these IgE-coated membrane targets are very effective in releasing serotonin from the rat basophil leukemia cells when the temperature is raised to 37 degrees C.

A new method for studying the physicochemical determinants of IgE-mediated activation of basophils is described. Rat basophil leukemia cells having IgE receptors were preincubated with monoclonal anti-dinitrophenyl IgE. These cells were then exposed to liposomes containing dinitrophenyl conjugated to phosphatidylethanolamine. The release of serotonin was measured. Using this system it was observed that liposomes containing dinitrophenyl conjugated to phosphatidylethanolamine by aminoethylformamidomethoxy acetyl (but not by caproic acid) were able to trigger the release of serotonin. "Solid" liposomes composed of dipalmitoylphosphatidylcholine and 2 mol % hapten were more potent inducers of serotonin release than "fluid" liposomes composed of dimyristoylphosphatidylcholine and hapten, but the fluid liposomes definitely triggered the cells to release serotonin. The addition of cholesterol to both types of liposomes enhanced their potency as activators and diminished the difference between the two types of phospholipid. This occurred despite the fact that cholesterol renders the solid liposomes fluid. Since it is unlikely that these fluid membranes can provide lateral forces that produce IgE-Fc receptor molecular clustering, we conclude that either receptor clustering is not necessary for basophil triggering, or molecular clustering is driven by molecular forces derived from IgE and components of the basophil cell.