Medical Device Daily Contributing Writer and MDDs

NORWICH, UK – A team from Imperial College London and Cambridge University has devised a way to image cells without killing them, making it possible to watch biology in action. Among the real-time processes recorded are the congregating of protein complexes, microvilli responding to changes in osmotic pressure and viruses preparing to infect a cell.

The researches have used their equipment to deliver single molecules to precise locations on the surface of cells. They have “painted” nanoscale pictures by the molecule-by-molecule application of fluorescent DNA and simulated a heart attack in a petri dish by administering a single molecule of a toxin to a cardiomyocyte, prompting it to become arrhythmic.

The technique, called Scanning Ion Conductance Microscopy (SICM) uses a micropipette to deliver a small voltage to the surface of the cell. By scanning the pipette across the cell, it is possible to create an image of the surface. No special preparation is required and the cells can be imaged on standard culture dishes.

In addition, the pipette can be used to perform nanoscale measurements on the cell surface, such as recording a single ion channel or for the controlled addition of reagents.

“The big advantage of our technique is that it is non-contact,” said David Klenerman, of Cambridge University, speaking at the British Association Science Festival here last week. “A lot of structural biology is based on examining dead cells. Now we can see live cells. It is not the highest resolution that has been achieved, but it is the highest achieved on a live cell.”

While SICM is not a new technique, the researchers have produced a micropipette that is smaller than any of its predecessors, enabling the resolution to go down to 10 nanometres.

Using fluorescent DNA, Klenerman and colleagues have painted the Cambridge University crest on a cell in lines that are under one micron in width. “This demonstrates very high control of where you put molecules and shows you can use the technique to do assays on individual living cells,” Klenerman said.

The team has studied epithelial kidney cells, uncovering the same features that are seen in scanning electron micrographs, but then going on to follow the life history of microvilli, showing them responding to changes in osmotic pressure. Currently, the researchers are applying the technique to visualise ion channels in neurons, and Klenerman said this is leading to the development of a smart patch clamp technique, where the characteristic on/off behavior of ion channels can be followed live.

The micropipettes can be used also to apply pressure to a cell, pushing it down or sucking it up, without actually making contact. That means that it is possible to probe the mechanical properties of individual cells.

Micropipettes can be constructed with a double barrel, to deliver two different molecules at the same time, and it also is possible to construct them with four and eight barrels.

The technique opens up the possibility of performing cell repairs, but Klenerman said that is some way off.

“We can locally deliver reagents, but at present we are getting information about normal cells and finding out about diseased cells. You could then think about using that information to repair damaged cells.”

Imperial College has spun out a company, Ionscope (London), to sell the equipment. Klenerman told Medical Device Daily's sister publication BioWorld International that this was suitable for research purposes only at present. “It is far from an established technology: There is some way to go before it could be applied systematically. But we have shown what is possible.”

CE-mark approvals

• Cyntellect (San Diego) reported that its Laser-Enabled Analysis and Processing (LEAP) System has won CE-marking.

LEAP is an automated instrument that combines high-speed optical imaging of cells, real-time image analysis and high-speed laser manipulation of individual live cells presented in microplate formats. It is designed to enable researchers to rapidly and selectively laser-irradiate specific cells achieving >99.9% purity. The in situ processing nature means researchers can exploit rare cell populations or cells that are typically refractory to currently available purification technologies (e.g. primary cells, patient cells or delicate cell lines) as well as more robust commonly used cell types.

Cyntellect said that LEAP-based laser manipulation of cells has also been demonstrated to effectively permeabilize cells transiently without inducing cellular toxicity. This approach, called LaserFect, enables introduction of a wide variety of biomolecules including ions, siRNAs, proteins and quantum dots, many of which cannot be transfected using current technologies.

• OptiMedica (Cannes, France/Santa Clara, California) reported receiving ISO 13485 certification and that its Pascal Photocoagulator has received CE-marking. Launched in the U.S. earlier this year, the Pascal Photocoagulator is now available for sale internationally.

OptiMedica holds the exclusive license to the PASCAL (PAttern SCAn Laser) method of photocoagulation and its associated technologies, which are FDA-approved to treat a variety of retinal conditions. The photocoagulator was previewed recently at the New Therapies in Retinal Diseases International Congress in Rome.

Jean-Robert Strele, vice president of international business for OptiMedica, said, “These approvals have come at just the right time for us, as we are exhibiting Pascal at two prestigious retina conferences this month as well as the American Academy of Ophthalmology in November.”

The first Pascal systems placed outside the U.S. will be at practices in Japan and Europe.

OptiMedica develops devices that treat ophthalmic disorders such as diabetic retinopathy, age-related macular degeneration, retinal vascular occlusive disease and retinal tears and detachments.

• Pall (East Hills, New York) reported recieving the CE mark for its eBDS System to detect bacterial contamination of red blood cells. The Pall eBDS is a culture-based test used by blood centers to detect bacterial contamination of platelets, the leading infectious cause of sickness and death from a transfusion. Results of a study presented at the International Society of Blood Transfusion (ISBT) 2006 Congress show the efficacy of the system in also detecting bacteria that are commonly found as contaminants of red blood cells.