Femtosecond plasma mediated laser ablation has advantages over mechanical osteotomy of cranial bone

BACKGROUND

Although mechanical osteotomies are frequently made on the craniofacial skeleton, collateral thermal, and mechanical trauma to adjacent bone tissue causes cell death and may delay healing. The present study evaluated the use of plasma-mediated laser ablation using a femtosecond laser to circumvent thermal damage and improve bone regeneration.

METHODS

Critical-size circular calvarial defects were created with a trephine drill bit or with a Ti:Sapphire femtosecond pulsed laser. Healing was followed using micro-CT scans for 8 weeks. Calvaria were also harvested at various time points for histological analysis. Finally, scanning electron microscopy was used to analyze the microstructure of bone tissue treated with the Ti:Sapphire laser, and compared to that treated with the trephine bur.

RESULTS

Laser-created defects healed significantly faster than those created mechanically at 2, 4, and 6 weeks post-surgery. However, at 8 weeks post-surgery, there was no significant difference. In the drill osteotomy treatment group, empty osteocyte lacunae were seen to extend 699 ± 27 µm away from the edge of the defect. In marked contrast, empty osteocyte lacunae were seen to extend only 182 ± 22 µm away from the edge of the laser-created craters. Significantly less ossification and formation of irregular woven bone was noted on histological analysis for drill defects.

CONCLUSIONS

We demonstrate accelerated bone healing after femtosecond laser ablation in a calvarial defect model compared to traditional mechanical drilling techniques. Improved rates of early regeneration make plasma-mediated ablation of the craniofacial skeleton advantageous for applications to osteotomy.

Intravital fluorescence imaging of small interfering RNA-mediated gene repression in a dual reporter melanoma xenograft model

Development of RNA interference (RNAi)-based therapeutics has been hampered by the lack of effective and efficient means of delivery. Reliable model systems for screening and optimizing delivery of RNAi-based agents in vivo are crucial for preclinical research aimed at advancing nucleic acid-based therapies. We describe here a dual fluorescent reporter xenograft melanoma model prepared by intradermal injection of human A375 melanoma cells expressing tandem tomato fluorescent protein (tdTFP) containing a small interfering RNA (siRNA) target site as well as enhanced green fluorescent protein (EGFP), which is used as a normalization control. Intratumoral injection of a siRNA specific to the incorporated siRNA target site, complexed with a cationic lipid that has been optimized for in vivo delivery, resulted in 65%±11% knockdown of tdTFP relative to EGFP quantified by in vivo imaging and 68%±10% by reverse transcription-quantitative polymerase chain reaction. No effect was observed with nonspecific control siRNA treatment. This model provides a platform on which siRNA delivery technologies can be screened and optimized in vivo.

Interrogation of inhibitor of nuclear factor κB α/nuclear factor κB (IκBα/NF-κB) negative feedback loop dynamics: from single cells to live animals in vivo

Full understanding of the biological significance of negative feedback processes requires interrogation at multiple scales as follows: in single cells, cell populations, and live animals in vivo. The transcriptionally coupled IκBα/NF-κB negative feedback loop, a pivotal regulatory node of innate immunity and inflammation, represents a model system for multiscalar reporters. Using a κB(5)→IκBα-FLuc bioluminescent reporter, we rigorously evaluated the dynamics of ΙκBα degradation and subsequent NF-κB transcriptional activity in response to diverse modes of TNFα stimulation. Modulating TNFα concentration or pulse duration yielded complex, reproducible, and differential ΙκBα dynamics in both cell populations and live single cells. Tremendous heterogeneity in the transcriptional amplitudes of individual responding cells was observed, which was greater than the heterogeneity in the transcriptional kinetics of responsive cells. Furthermore, administration of various TNFα doses in vivo generated ΙκBα dynamic profiles in the liver resembling those observed in single cells and populations of cells stimulated with TNFα pulses. This suggested that dose modulation of circulating TNFα was perceived by hepatocytes in vivo as pulses of increasing duration. Thus, a robust bioluminescent reporter strategy enabled rigorous quantitation of NF-κB/ΙκBα dynamics in both live single cells and cell populations and furthermore, revealed reproducible behaviors that informed interpretation of in vivo studies.

Inhibition of CD44 gene expression in human skin models, using self-delivery short interfering RNA administered by dissolvable microneedle arrays

Treatment of skin disorders with short interfering RNA (siRNA)-based therapeutics requires the development of effective delivery methodologies that reach target cells in affected tissues. Successful delivery of functional siRNA to the epidermis requires (1) crossing the stratum corneum, (2) transfer across the keratinocyte membrane, followed by (3) incorporation into the RNA-induced silencing complex. We have previously demonstrated that treatment with microneedle arrays loaded with self-delivery siRNA (sd-siRNA) can achieve inhibition of reporter gene expression in a transgenic mouse model. Furthermore, treatment of human cultured epidermal equivalents with sd-siRNA resulted in inhibition of target gene expression. Here, we demonstrate inhibition of CD44, a gene that is uniformly expressed throughout the epidermis, by sd-siRNA both in vitro (cultured human epidermal skin equivalents) and in vivo (full-thickness human skin equivalents xenografted on immunocompromised mice). Treatment of human skin equivalents with CD44 sd-siRNA markedly decreased CD44 mRNA levels, which led to a reduction of the target protein as confirmed by immunodetection in epidermal equivalent sections with a CD44-specific antibody. Taken together, these results demonstrate that sd-siRNA, delivered by microneedle arrays, can reduce expression of a targeted endogenous gene in a human skin xenograft model.

Development of B cells and erythrocytes is specifically impaired by the drug celastrol in mice

Background

Celastrol, an active compound extracted from the root of the Chinese medicine “Thunder of God Vine” (Tripterygium wilfordii), exhibits anticancer, antioxidant and anti-inflammatory activities, and interest in the therapeutic potential of celastrol is increasing. However, described side effects following treatment are significant and require investigation prior to initiating clinical trials. Here, we investigated the effects of celastrol on the adult murine hematopoietic system.

Methodology/Principal Findings

Animals were treated daily with celastrol over a four-day period and peripheral blood, bone marrow, spleen, and peritoneal cavity were harvested for cell phenotyping. Treated mice showed specific impairment of the development of B cells and erythrocytes in all tested organs. In bone marrow, these alterations were accompanied by decreases in populations of common lymphoid progenitors (CLP), common myeloid progenitors (CMP) and megakaryocyte-erythrocyte progenitors (MEP).

Conclusions/Significance

These results indicate that celastrol acts through regulators of adult hematopoiesis and could be used as a modulator of the hematopoietic system. These observations provide valuable information for further assessment prior to clinical trials.

Abstract LB-419: Multi-scalar approaches to interrogate the IκBα:NF-κB negative feedback loop: Quantitative dynamics in single cells, cell populations, and live animals in vivo

Cells have evolved complex molecular networks to sense environmental signals, transmit this information through the cell, and elicit appropriate biological responses. In particular, negative feedback loops represent a widely-utilized network motif capable of eliciting transient responses. To truly understand the biological significance of negative feedback processes, it is critical to study them at multiple scales: in single cells, in cell populations, and in animals. The IκBα:NF-κB negative feedback loop, a pivotal regulatory node of innate immunity and inflammation active in both immune cells and non-immune tissues, represents a model system for the use of multi-scalar reporter systems. To this end, we have utilized the κB5→IκBα-FLuc bioluminescent reporter to study dynamics of this transcriptionally-coupled negative feedback loop in response to diverse modes of stimulation which may be particularly relevant during cellular responses to inflammatory cytokines, such as TNFα. The κB5→IκBα-FLuc reporter enabled rigorous evaluation of the stimulus-specific dynamics of βκγα degradation and the downstream consequences of NF-κΔ nuclear translocation (i.e., NF-κΔ transcriptional activity) in single cells, cell populations and live animals in vivo. In response to modulation of TNFα concentration and pulse duration, complex, differential patterns in βκγα degradation and re-synthesis were discovered in both cell populations and single cells. Furthermore, IκBα dynamics observed in live animals in vivo upon modulation of TNFα dose strongly resembled those observed in single cells and cell populations upon modulating TNFα pulse duration, suggesting that increased doses of circulating TNFα were perceived by hepatocytes in vivo as pulses of increasing duration. Thus, a single bioluminescent reporter strategy enabled correlative quantitation of dynamic NF-κα:βκβα negative feedback loop responses in live single cells, cell populations, and tissues in vivo with a variety of rapid, low-cost, high-throughput approaches.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-419. doi:1538-7445.AM2012-LB-419

Abstract SY24-01: Use of imaging to guide the development of immune cell therapies

Advances in in vivo imaging have enabled the study of cellular and molecular biology in living animals models of human disease. When integrated with thorough studies in cell culture and directed ex vivo analyses, these tools can reveal the nuances of cellular mechanisms and the subtlety of therapeutic responses. This is leading to the identification and interrogation of molecular targets at a level that was not previously possible, and is refining and accelerating the study of novel therapeutic strategies directed at these targets. The impact of molecular imaging has been most dramatic in preclinical studies of animal models and is moving into clinical studies. With these tools we have a unique opportunity to ask, and answer, hard questions about disease processes and novel therapies in the context of living tissues. By preserving the tissue structure and cellular function in these studies we can gain more information that is more relevant to the disease processes. The advances in stem cell biology and transgenic sciences are creating animal models that are more relevant to human disease and response to therapy, and imaging is accelerating the study of these more predictive models. Molecular imaging is leading to new insights, and enabling new approaches in the emerging fields of stem cell therapy, nanotechnology and regenerative medicine. This is leading to dramatic changes in the way we screen and develop new drugs. It is likely that these visible animal models of human biology and disease comprise one of the most important contributions of molecular imaging to human health as they serve to accelerate and refine the analyses of mammalian biology and offer a rapid readout for the development of new therapies. Using imaging we have developed a combination of two well-developed biotherapies that together maximize delivery, and improve efficacy in preclinical models of ovarian cancer. The dual biotherapy is comprised of immunotherapy with cytokine induced killer (CIK) cells, and oncolytic virotherapy with an attenuated vaccinia virus. These two therapies have a proven safety record with decades of clinical evaluation of each individual biotherapy, but alone the therapies lack efficacy. The limitations of each therapy are well understood and explain the lack of efficacy. In considering these limitations we proposed and tested the combination therapy and demonstrated a complementarity that overcomes the limitations of each individual therapy and creates a therapeutic synergy that is highly efficacious in preclinical studies. Transporting cytotoxic agents to tumor targets has been the goal of cell-mediated delivery, however, immune cells can also i) produce their own tumoricidal effect, ii) conceal a payload from an immune response, iii) amplify a selective agent at the target site and iv) facilitate an antitumor immune response. Integrating the biology of a cellular delivery vehicle with that of the therapeutic payload, vaccinia virus, leads to enhanced antitumor effects. Both of the agents display broad tumor-targeting potential and possess unique tumor killing mechanisms, together the therapies are able to recognize and destroy a far greater number and diversity of malignant cells within the heterogeneous tumor than either agent alone. Effective cancer therapy will require recognition and elimination of the root of the disease, the cancer stem cell, and this combination has this potential. The tumor-selectivity of oncolytic viruses is due to modifications that take advantage of the unique biology of the cancer cell, and similar modifications for integration into the delivery vehicle increases the safety and improves therapeutic outcome. In this dose escalation trail the cell numbers will be fixed and the dose of virus increased, and we will use imaging methods as rapid measures of treatment response to asses efficacy and guide future development.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr SY24-01. doi:1538-7445.AM2012-SY24-01

Molecular imaging of inflammation and carcinogenesis

Development of imaging agents that can be used broadly for early detection of neoplasia at various tissue sites and at various stages of disease and that also can assess states of minimal residual disease would have tremendous utility in the diagnosis and management of cancer. In a series of articles culminating with a report in this issue of the journal (beginning on page 1536), Uddin and colleagues show their ability to systemically target the enzyme COX-2 with imaging probes that will serve as agents for early detection, risk assessment, prognosis, and intervention outcome measures. These probes will enable the detection and localization of regions of inflammation and a wide variety of premalignant lesions and cancers, with utility in monitoring the effects of cancer prevention and therapy.

In vivo near-infrared dual-axis confocal microendoscopy in the human lower gastrointestinal tract

Near-infrared confocal microendoscopy is a promising technique for deep in vivo imaging of tissues and can generate high-resolution cross-sectional images at the micron-scale. We demonstrate the use of a dual-axis confocal (DAC) near-infrared fluorescence microendoscope with a 5.5-mm outer diameter for obtaining clinical images of human colorectal mucosa. High-speed two-dimensional en face scanning was achieved through a microelectromechanical systems (MEMS) scanner while a micromotor was used for adjusting the axial focus. In vivo images of human patients are collected at 5 frames/sec with a field of view of 362×212 μm(2) and a maximum imaging depth of 140 μm. During routine endoscopy, indocyanine green (ICG) was topically applied a nonspecific optical contrasting agent to regions of the human colon. The DAC microendoscope was then used to obtain microanatomic images of the mucosa by detecting near-infrared fluorescence from ICG. These results suggest that DAC microendoscopy may have utility for visualizing the anatomical and, perhaps, functional changes associated with colorectal pathology for the early detection of colorectal cancer.

In vivo sustained release of siRNA from solid lipid nanoparticles

Small interfering RNA (siRNA) is a highly potent drug in gene-based therapy with a challenge of being delivered in a sustained manner. Nanoparticle drug delivery systems allow for incorporating and controlled release of therapeutic payloads. We demonstrate that solid lipid nanoparticles can incorporate and provide sustained release of siRNA. Tristearin solid lipid nanoparticles, made by nanoprecipitation, were loaded with siRNA (4.4-5.5 wt % loading ratio) using a hydrophobic ion pairing approach that employs the cationic lipid DOTAP. Intradermal injection of these nanocarriers in mouse footpads resulted in prolonged siRNA release over a period of 10-13 days. In vitro cell studies showed that the released siRNA retained its activity. Nanoparticles developed in this study offer an alternative approach to polymeric nanoparticles for encapsulation and sustained delivery of siRNA with the advantage of being prepared from physiologically well-tolerated materials.

Visualization of plasmid delivery to keratinocytes in mouse and human epidermis

The accessibility of skin makes it an ideal target organ for nucleic acid-based therapeutics; however, effective patient-friendly delivery remains a major obstacle to clinical utility. A variety of limited and inefficient methods of delivering nucleic acids to keratinocytes have been demonstrated; further advances will require well-characterized reagents, rapid noninvasive assays of delivery, and well-developed skin model systems. Using intravital fluorescence and bioluminescence imaging and a standard set of reporter plasmids we demonstrate transfection of cells in mouse and human xenograft skin using intradermal injection and two microneedle array delivery systems. Reporter gene expression could be detected in individual keratinocytes, in real-time, in both mouse skin as well as human skin xenografts. These studies revealed that non-invasive intravital imaging can be used as a guide for developing gene delivery tools, establishing a benchmark for comparative testing of nucleic acid skin delivery technologies.

Point-of-care pathology with miniature microscopes

Advances in optical designs are enabling the development of miniature microscopes that can examine tissue in situ for early anatomic and molecular indicators of disease, in real time, and at cellular resolution. These new devices will lead to major changes in how diseases are detected and managed, driving a shift from today's diagnostic paradigm of biopsy followed by histopathology and recommended therapy, to non-invasive point-of-care diagnosis with possible same-session definitive treatment. This shift may have major implications for the training requirements of future physicians to enable them to interpret real-time in vivo microscopic data, and will also shape the emerging fields of telepathology and telemedicine. Implementation of new technologies into clinical practice is a complex process that requires bridging gaps between clinicians, engineers and scientists. This article provides a forward-looking discussion of these issues, with a focus on malignant and pre-malignant lesions, by first highlighting some of the clinical areas where point-of-care in vivo microscopy could address unmet needs, and then by reviewing the technological challenges that are being addressed, or need to be addressed, for in vivo microscopy to become a standard clinical tool.

Pulse duration determines levels of Hsp70 induction in tissues following laser irradiation

Induction of heat shock protein (Hsp) expression correlates with cytoprotection, reduced tissue damage, and accelerated healing in animal models. Since Hsps are transcriptionally activated in response to stress, they can act as stress indicators in burn injury or surgical procedures that produce heat and thermal change. A fast in vivo readout for induction of Hsp transcription in tissues would allow for the study of these proteins as therapeutic effect mediators and reporters of thermal stress∕damage. We used a transgenic reporter mouse in which a luciferase expression is controlled by the regulatory region of the inducible 70 kilodalton (kDa) Hsp as a rapid readout of cellular responses to laser-mediated thermal stress∕injury in mouse skin. We assessed the pulse duration dependence of the Hsp70 expression after irradiation with a CO(2) laser at 10.6 μm in wavelength over a range of 1000 to 1 ms. Hsp70 induction varied with changes in laser pulse durations and radiant exposures, which defined the ranges at which thermal activation of Hsp70 can be used to protect cells from subsequent stress, and reveals the window of thermal stress that tissues can endure.

Heme oxygenase-1 deletion affects stress erythropoiesis

Background

Homeostatic erythropoiesis leads to the formation of mature red blood cells under non-stress conditions, and the production of new erythrocytes occurs as the need arises. In response to environmental stimuli, such as bone marrow transplantation, myelosuppression, or anemia, erythroid progenitors proliferate rapidly in a process referred to as stress erythropoiesis. We have previously demonstrated that heme oxygenase-1 (HO-1) deficiency leads to disrupted stress hematopoiesis. Here, we describe the specific effects of HO-1 deficiency on stress erythropoiesis.

Methodology/Principal Findings

We used a transplant model to induce stress conditions. In irradiated recipients that received hmox^+/− or hmox^+/+ bone marrow cells, we evaluated (i) the erythrocyte parameters in the peripheral blood; (ii) the staining intensity of CD71-, Ter119-, and CD49d-specific surface markers during erythroblast differentiation; (iii) the patterns of histological iron staining; and (iv) the number of Mac-1⁺-cells expressing TNF-α. In the spleens of mice that received hmox^+/− cells, we show (i) decreases in the proerythroblast, basophilic, and polychromatophilic erythroblast populations; (ii) increases in the insoluble iron levels and decreases in the soluble iron levels; (iii) increased numbers of Mac-1⁺-cells expressing TNF-α; and (iv) decreased levels of CD49d expression in the basophilic and polychromatophilic erythroblast populations.

Conclusions/Significance

As reflected by effects on secreted and cell surface proteins, HO-1 deletion likely affects stress erythropoiesis through the retention of erythroblasts in the erythroblastic islands of the spleen. Thus, HO-1 may serve as a therapeutic target for controlling erythropoiesis, and the dysregulation of HO-1 may be a predisposing condition for hematologic diseases.

Image-guided genomic analysis of tissue response to laser-induced thermal stress

The cytoprotective response to thermal injury is characterized by transcriptional activation of "heat shock proteins" (hsp) and proinflammatory proteins. Expression of these proteins may predict cellular survival. Microarray analyses were performed to identify spatially distinct gene expression patterns responding to thermal injury. Laser injury zones were identified by expression of a transgene reporter comprised of the 70 kD hsp gene and the firefly luciferase coding sequence. Zones included the laser spot, the surrounding region where hsp70-luc expression was increased, and a region adjacent to the surrounding region. A total of 145 genes were up-regulated in the laser irradiated region, while 69 were up-regulated in the adjacent region. At 7 hours the chemokine Cxcl3 was the highest expressed gene in the laser spot (24 fold) and adjacent region (32 fold). Chemokines were the most common up-regulated genes identified. Microarray gene expression was successfully validated using qRT- polymerase chain reaction for selected genes of interest. The early response genes are likely involved in cytoprotection and initiation of the healing response. Their regulatory elements will benefit creating the next generation reporter mice and controlling expression of therapeutic proteins. The identified genes serve as drug development targets that may prevent acute tissue damage and accelerate healing.

Abstract SY03-01: Molecular imaging with cellular resolution and molecular specificity using miniaturized microscopes

The earliest malignant lesions are microscopic in size and may be characterized by abnormal cell surface markers and disrupted microanatomy. The challenge for early detection of cancer is effectively using these features to localize and characterize those early lesions that are likely to progress. For cancers of the gastrointestinal (GI) tract there are some predisposing conditions that identify high-risk regions, and justify microscopic analyses for detection, diagnosis and guided biopsy of small, early lesions. In addition, microscopic analyses are used for detection of tumor margins in resection of skin and breast cancer and may have utility in resection of cancers.

Micro-optical designs are enabling the development of miniaturized microscopes that can reach inside the body to interrogate disease states with cellular resolution. In combination with molecular probes such instruments can be used to interrogate suspect lesions for early signs of malignancy and to determine if margins are clear. To enable molecular imaging with cellular resolution, we have developed miniaturized confocal fluorescence microscopes that are based on a dual-axis architecture. The dual-axis design enables the use of low numerical aperture lenses and a folded light path that is amenable to a small form factor and post objective scanning in the scan head. The design features of this microscope included axial and transverse resolutions comparable to that used by pathologists (5 µM), and a 0.5 × 0.5 × 0.5 mm 3-D field of view in an instrument that has an external diameter compatible with use in an endoscope for GI cancers, and that can reach into small cavities for guided resections.

The first dual-axis confocal (DAC) microscope that has been used in a clinical study in the colon with these capabilities has a 5-mm external diameter and an excitation wavelength of 780 nm. To enable early detection we have developed and tested a number of optical probes for use as molecular markers, and evaluated FDA-approved dyes as contrast for analysis of microanatomy. Studies in animals and man demonstrated the ability to observe microanatomy and discriminate malignant tissue from surrounding normal tissues. A wide variety of fluorescent agents are being developed and tested for cancer detection using macroscopic approaches. These agents can be detected at the cellular level with miniaturized microscopes for complementary analyses. Placement of the microscope can be guided by the macroscopic images, and the microscopic data can be used to substantiate the images. We have targeted surface markers and the cytoplasmic enzyme Cox-2 in these studies. We fitted the DAC microscopes with a needle lens to reach deep into the tissues and this instrument has been evaluated for guided resections of medulloblastoma in preclinical studies. The next-generation instruments have a smaller form factor and are designed for multispectral capabilities and faster scan times. This will increase their utility with increased access to tissues sites and multiplexed in vivo assays.

The co-development of molecular probes and micro-optical instruments to visualize cancer may improve detection of cancer, and can be used to assess therapeutic outcome. Advances in in vivo microscopy could lead to a fundamental shift in the diagnostic paradigm from biopsy with conventional histopathology to performance of point-of-care morphologic diagnosis using in vivo microscopic pathology. These technologies are closing the gap between the patient and the diagnostic event, and will have major ramifications for the training of future physicians to interpret real-time in vivo microscopic molecular data, and will advance the emerging field of telepathology. One of the features of multimodality molecular imaging is reaching across a range of scales from microscopic, cellular resolution, to macroscopic, whole body, imaging and new tools with microscopic capabilities are necessary to achieve these aims

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr SY03-01. doi:10.1158/1538-7445.AM2011-SY03-01

Non-damaging retinal phototherapy: dynamic range of heat shock protein expression

PURPOSE

Subthreshold retinal phototherapy demonstrated clinical efficacy for the treatment of diabetic macular edema without visible signs of retinal damage. To assess the range of cellular responses to sublethal hyperthermia, expression of the gene encoding a 70 kDa heat shock protein (HSP70) was evaluated after laser irradiation using a transgenic reporter mouse.

METHODS

One hundred millisecond, 532 nm laser exposures with 400 μm beam diameter were applied to the retina surrounding the optic nerve in 32 mice. Transcription from the HSP70 promoter was assessed relative to the control eye using a bioluminescence assay at 7 hours after laser application. The retinal pigmented epithelium (RPE) viability threshold was determined with a fluorescence assay. A computational model was developed to estimate temperature and the extent of cell damage.

RESULTS

A significant increase in HSP70 transcription was found at exposures over 20 mW, half the threshold power for RPE cell death. Computational modeling estimated peak temperature T = 49°C at HSP70 expression threshold. At RPE viability threshold, T = 57°C. Similar temperatures and damage indices were calculated for clinical subvisible retinal treatment parameters.

CONCLUSIONS

Beneficial effects of laser therapy have been previously shown to extend beyond those resulting from destruction of tissue. One hundred millisecond laser exposures at approximately half the threshold power of RPE damage induced transcription of HSP70, an indication of cellular response to sublethal thermal stress. A computational model of retinal hyperthermia can guide further optimization of laser parameters for nondamaging phototherapy.

Longitudinal, noninvasive imaging of T-cell effector function and proliferation in living subjects

Adoptive immunotherapy is evolving to assume an increasing role in treating cancer. Most imaging studies in adoptive immunotherapy to date have focused primarily on locating tumor-specific T cells rather than understanding their effector functions. In this study, we report the development of a noninvasive imaging strategy to monitor T-cell activation in living subjects by linking a reporter gene to the Granzyme B promoter (pGB), whose transcriptional activity is known to increase during T-cell activation. Because pGB is relatively weak and does not lead to sufficient reporter gene expression for noninvasive imaging, we specifically employed 2 signal amplification strategies, namely the Two Step Transcription Amplification (TSTA) strategy and the cytomegalovirus enhancer (CMVe) strategy, to maximize firefly luciferase reporter gene expression. Although both amplification strategies were capable of increasing pGB activity in activated primary murine splenocytes, only the level of bioluminescence activity achieved with the CMVe strategy was adequate for noninvasive imaging in mice. Using T cells transduced with a reporter vector containing the hybrid pGB-CMVe promoter, we were able to optically image T-cell effector function longitudinally in response to tumor antigens in living mice. This methodology has the potential to accelerate the study of adoptive immunotherapy in preclinical cancer models.

Development of quantitative molecular clinical end points for siRNA clinical trials

RNA interference (RNAi) is an evolutionarily conserved mechanism that results in specific gene inhibition at the mRNA level. The discovery that short interfering RNAs (siRNAs) are selective, potent, and can largely avoid immune surveillance has resulted in keen interest to develop these inhibitors as therapeutics. A single nucleotide-specific siRNA (K6a_513a.12, also known as TD101) was recently evaluated in a phase 1b clinical trial for the rare skin disorder, pachyonychia congenita (PC). To develop a clinical trial molecular end point for this type of trial, methods were developed to: (1) isolate total RNA containing amplifiable mRNA from human skin and callus material; (2) quantitatively distinguish the single-nucleotide mutant mRNA from wild-type K6a mRNA in both patient-derived keratinocytes and patient callus; and (3) demonstrate that repeated siRNA treatment results in sustained inhibition of mutant K6a mRNA in patient-derived keratinocyte cultures. These methods allow noninvasive sampling and monitoring of gene expression from patient-collected shavings and may be useful in evaluating the effectiveness of RNAi-based therapeutics, including inhibitors that specifically target single-nucleotide mutations.

Definition of an enhanced immune cell therapy in mice that can target stem-like lymphoma cells

Current treatments of high-grade lymphoma often have curative potential, but unfortunately many patients relapse and develop therapeutic resistance. Thus, there remains a need for novel therapeutics that can target the residual cancer cells whose phenotypes are distinct from the bulk tumor and that are capable of reforming tumors from very few cells. Oncolytic viruses offer an approach to destroy tumors by multiple mechanisms, but they cannot effectively reach residual disease or micrometastases, especially within the lymphatic system. To address these limitations, we have generated immune cells infected with oncolytic viruses as a therapeutic strategy that can combine effective cellular delivery with synergistic tumor killing. In this study, we tested this approach against minimal disease states of lymphomas characterized by the persistence of cancer cells that display stem cell-like properties and resistance to conventional therapies. We found that the immune cells were capable of trafficking to and targeting residual cancer cells. The combination biotherapy used prevented relapse by creating a long-term, disease-free state, with acquired immunity to the tumor functioning as an essential mediator of this effect. Immune components necessary for this acquired immunity were identified. We further demonstrated that the dual biotherapy could be applied before or after conventional therapy. Our approach offers a potentially powerful new way to clear residual cancer cells, showing how restoring immune surveillance is critical for maintenance of a disease-free state.

In vivo micro-image mosaicing

Recent advances in optical imaging have led to the development of miniature microscopes that can be brought to the patient for visualizing tissue structures in vivo. These devices have the potential to revolutionize health care by replacing tissue biopsy with in vivo pathology. One of the primary limitations of these microscopes, however, is that the constrained field of view can make image interpretation and navigation difficult. In this paper, we show that image mosaicing can be a powerful tool for widening the field of view and creating image maps of microanatomical structures. First, we present an efficient algorithm for pairwise image mosaicing that can be implemented in real time. Then, we address two of the main challenges associated with image mosaicing in medical applications: cumulative image registration errors and scene deformation. To deal with cumulative errors, we present a global alignment algorithm that draws upon techniques commonly used in probabilistic robotics. To accommodate scene deformation, we present a local alignment algorithm that incorporates deformable surface models into the mosaicing framework. These algorithms are demonstrated on image sequences acquired in vivo with various imaging devices including a hand-held dual-axes confocal microscope, a miniature two-photon microscope, and a commercially available confocal microendoscope.