Successful cell and molecular imaging relies on advances in both contrast agents and imaging systems.  Our team includes experts in the design and evaluation of high resolution imaging systems.  We bring together faculty with expertise in development of imaging systems ranging from ultrahigh resolution microscopy to  image  molecules  and  macromolecular  aggregates  (Malcolm  Brown)  to  endoscopic  microscopes  to visualize  human  tissue  in  vivo (Tom  Milner,  Rebecca  Richards-Kortum, AJ  Welch). We have deliberately included faculty with interests in ultra high resolution, ultra-sensitive imaging systems which are currently focused on more basic research and those developing systems for immediate clinical use so that students can appreciate this entire spectrum.  The combined expertise of our imaging faculty enables study of interdisciplinary topics, which push the limits of currently available systems.  

As an example with immediate clinical impact, Drs. Smalling  and Milner are developing differential phase optical  coherence  tomography  (DP-OCT)  and  intravascular  ultrasound (IVUS)  to  identify  and  characterize vulnerable  plaques  in  coronary  arteries. Optical Coherence Tomography (OCT) is a technique for high resolution imaging of strongly scattering biological tissues. Their approach  combines  IVUS  and DP-OCT to  provide  high  resolution  (5-10  µm) tomographic  images  of  vulnerable  plaques  in  coronary  arteries.   Rapid rotation of a microprism  at  the distal end of a catheter probe allows construction of a three-dimensional tomographic map of the luminal side of a coronary artery.  The investigators are working to develop a hybrid intravascular tomographic imaging  method  that  can  provide  co-registered  optical  and  acoustic  images  that  would  have  decided advantages over existing methods.  

Dr.  Richards-Kortum is collaborating with Drs. Follen and Gillenwater to develop spectroscopic  and  imaging  instrumentation  for  in  vivo  detection  of  cancer  and  its  precursors. Their groups have developed spectrometers to measure fluorescence excitation emission matrices and reflectance spectra at multiple source detector separations.  These instruments have been used in clinical  trials  of  over  1,500  patients  at  UTMDACC  to  determine  the  optical  properties  of  normal  and precancerous tissues of the uterine cervix and oral cavity. Results show that this information can be used to discriminate precancers with high sensitivity and specificity.  Based  on  these  results,  their groups  have  recently  developed  low  cost  instrumentation  to  image  the  fluorescence  and  reflectance  of tissue in real time. 

The ability to monitor not only molecular biomarkers of disease in the body  but  also  the  distribution  and transport  of  biological  compounds  in individual cells is a growing frontier of diagnostic  and  therapeutic  technology, and  it  is  an  area  that  relies  on  the development of novel imaging systems and  collaborative  approaches.   One such collaboration has united the strengths of the Shear and Brodbelt groups.  A primary interest of  the  Shear  group  is  examination  of how the intracellular chemistry of cells may  be  controlled  and  monitored  in  site-specific  ways,  along  with development  of  strategies  for restricting  the  action  of  signal transduction  enzymes  and  enzyme inhibitors to highly localized cytosolic coordinates. Characterization  of subcellular  chemical events,  such  as neurotransmitter  release at a synapse, requires the ability to separate and measure  very  small quantities  of  a  diverse set  of  molecules.  The Shear group is exploring the use of capillary electrophoresis and multiphoton-excited fluorescence to probe various biological fluorophores, including the neurotransmitters serotonin and dopamine, and europeptides such as the enkephalins.  These new methods are applicable to samples as small as 100 femtoliters which will allow analysis of single cells.  The Brodbelt group is  developing  mass  spectrometric  methods  for  structural  characterization  and  quantitation  of  biological molecules  in  physiological  matrices.  Electrospray  ionization  is  used  to  transport  species  directly  from solution  into  the  mass  spectrometer,  and  tandem mass  spectrometric  methods  allow  elucidation  of  the structures.  IGERT trainee Courtney Sherman is participating in the development of an on-line method for monitoring the photodegradation products of neurotransmitters, allowing confirmation of the types of products formed.  

A  strength  of  our  IGERT  program  is  that  we  bring  together  faculty  with  diverse  backgrounds.  For example, Professors Barbara, Shih and Vandenbout have developed and use sensitive imaging and spectroscopy tools to study heterogeneous materials such as near-field scanning optical microscopy and single molecule spectroscopy. Here, we bring these basic research tools to bear on biological problems by providing an environment with the necessary mix of disciplines.   The  Barbara  group  is  studying retrovirus  replication,  by  means  of  single  molecule  fluorescence  resonance  energy  transfer.  The Vandenbout and Brown labs have pioneered several high resolution light and electron optical methods. Brown and IGERT trainee Andrew Bowling are using AFM, light microscopy and HRTEM to monitor biosynthetic reactions of enzyme complexes in single plasma membrane sheets mounted on synthetic substrates.  Using  this  technology,  it  is  possible  to  monitor  a  wide  variety  of  biosynthetic functions simultaneously using antibody and fluorescent brighteners to bind to products in real time. With HRTEM, it is possible to image single polymer glucan chains of cellulose or single peptides, DNA, cyclic glucans.  Vandenbout is developing a high resolution near field light microscope for detecting macromolecular aggregates using time-resolved and polarized fluorescence as a local probe of molecular order.  The high resolution of NSOM combined with fluorescence allows for determination of molecular order in domains as small as 25 nm.  With isolated chromophores the orientation of individual molecules or aggregates can be measured. Combining immunodetection with molecular imaging (electron,  force, and optical) is a powerful tool in the novel imaging system development in this program.  

The focus of our current IGERT  program  is  optical spectroscopy  and  imaging;  in this  renewal,  we  expand  our efforts  to  include  multimodal imaging.    Professor  Stas Emelianov  is  one  of  the  most recently  recruited  faculty  in BME at UT Austin.  His area of expertise  is  ultrasound microscopy,  and  as  part  of  this renewal,  he  will  develop interdisciplinary  collaborations to  provide  multimodal  optical and  ultrasonic  images  of  living specimens  with  cellular resolution.  Finally, image processing  is  an  integral  part  of cellular  and  molecular  imaging for  a  number  of  reasons  that include  de-noising  the  data, retrospective image alignment for longitudinal follow up and fusing and visualization of information from multiple  image  modalities. UT  Austin  is  a  leader  in  the  development  of  image  processing  and visualization.  Working with Professors Bovik, Narayana and others we will further expand these types of collaborations through interactions with faculty at UTMDACC and UTHSC-H.