Behavioral assessment of neuropathic pain, fatigue, and anxiety in experimental autoimmune encephalomyelitis (EAE) and attenuation by interleukin-10 gene therapy

Relapsing-remitting multiple sclerosis is commonly associated with motor impairments, neuropathic pain, fatigue, mood disorders, and decreased life expectancy. However, preclinical pharmacological studies predominantly rely on clinical scoring of motor deficit as the sole behavioral endpoint. Thus, the translational potential of these studies is limited. Here, we have assessed the therapeutic potential of a novel anti-inflammatory interleukin-10 (IL-10) non-viral gene therapy formulation (XT-101-R) in a rat relapsing remitting experimental autoimmune encephalomyelitis (EAE) model. EAE induced motor deficits and neuropathic pain as reflected by induction of low-threshold mechanical allodynia, suppressed voluntary wheel running, decreased social exploration, and was associated with markedly enhanced mortality. We also noted that voluntary wheel running was depressed prior to the onset of motor deficit, and may therefore serve as a predictor of clinical symptoms onset. XT-101-R was intrathecally dosed only once at the onset of motor deficits, and attenuated each of the EAE-induced symptoms and improved survival, relative to vehicle control. This is the first pharmacological assessment of such a broad range of EAE symptoms, and provides support for IL-10 gene therapy as a clinical strategy for the treatment of multiple sclerosis.

Enzymatically degradable poly(ethylene glycol) hydrogels for the 3D culture and release of human embryonic stem cell derived pancreatic precursor cell aggregates

This study aimed to develop a three dimensional culture platform for aggregates of human embryonic stem cell (hESC)-derived pancreatic progenitors that enables long-term culture, maintains aggregate size and morphology, does not adversely affect differentiation and provides a means for aggregate recovery. A platform was developed with poly(ethylene glycol) hydrogels containing collagen type I, for cell-matrix interactions, and peptide crosslinkers, for facile recovery of aggregates. The platform was first demonstrated with RIN-m5F cells, showing encapsulation and subsequent release of single cells and aggregates without adversely affecting viability. Aggregates of hESC-derived pancreatic progenitors with an effective diameter of 82 (15)μm were either encapsulated in hydrogels or cultured in suspension for 28 days. At day 14, aggregate viability was maintained in the hydrogels, but significantly reduced (88%) in suspension culture. However by day 28, viability was reduced under both culture conditions. Aggregate size was maintained in the hydrogels, but in suspension was significantly higher (∼ 2-fold) by day 28. The ability to release aggregates followed by a second enzyme treatment to achieve single cells enabled assessment by flow cytometry. Prior to encapsulation, there were 39% Pdx1(+)/Nkx6.1(+) cells, key endocrine markers required for β-cell maturation. The fraction of doubly positive cells was not affected in hydrogels but was slightly and significantly lower in suspension culture by 28 days. In conclusion, we demonstrate that a MMP-sensitive PEG hydrogel containing collagen type I is a promising platform for hESC-derived pancreatic progenitors that maintains viable aggregates, aggregate size, and progenitor state and offers facile recovery of aggregates.

Tissue engineering approaches to cell-based type 1 diabetes therapy

Type 1 diabetes mellitus is an autoimmune disease resulting from the destruction of insulin-producing pancreatic β-cells. Cell-based therapies, involving the transplantation of functional β-cells into diabetic patients, have been explored as a potential long-term treatment for this condition; however, success is limited. A tissue engineering approach of culturing insulin-producing cells with extracellular matrix (ECM) molecules in three-dimensional (3D) constructs has the potential to enhance the efficacy of cell-based therapies for diabetes. When cultured in 3D environments, insulin-producing cells are often more viable and secrete more insulin than those in two dimensions. The addition of ECM molecules to the culture environments, depending on the specific type of molecule, can further enhance the viability and insulin secretion. This review addresses the different cell sources that can be utilized as β-cell replacements, the essential ECM molecules for the survival of these cells, and the 3D culture techniques that have been used to benefit cell function.

Spinal interleukin-10 therapy to treat peripheral neuropathic pain

INTRODUCTION

  Current research indicates that chronic peripheral neuropathic pain includes a role for glia and the actions of proinflammatory factors. This review briefly discusses the glial and cytokine responses that occur following peripheral nerve damage in support of utilizing anti-inflammatory cytokine interleukin-10 (IL-10) therapy to suppress chronic peripheral neuropathic pain. SPINAL NONVIRAL INTERLEUKIN-10 GENE THERAPY:  IL-10 is one of the most powerful endogenous counter-regulators of proinflammatory cytokine function that acts in the nervous system. Subarachnoid (intrathecal) spinal injection of the gene encoding IL-10 delivered by nonviral vectors has several advantages over virally mediated gene transfer methods and leads to profound pain relief in several animal models. NONVIRAL GENE DELIVERY:  Lastly, data are reviewed that nonviral deoxyribonucleic acid (DNA) encapsulated by a biologically safe copolymer, poly(lactic-co-glycolic) acid (PLGA), thought to protect DNA, leads to significantly improved therapeutic gene transfer in animal models, which additionally and significantly extends pain relief.

CONCLUSIONS

  The impact of these early studies exploring anti-inflammatory genes emphasizes the exceptional therapeutic potential of new biocompatible intrathecal nonviral gene delivery approaches such as PLGA microparticles. Ultimately, ongoing expression of therapeutic genes is a viable option to treat chronic neuropathic pain in the clinic.

Inhibition of gamma-secretase activity promotes differentiation of embryonic pancreatic precursor cells into functional islet-like clusters in poly(ethylene glycol) hydrogel culture

We assessed the ability of a gamma-secretase inhibitor to promote the in vitro differentiation of induced embryonic pancreatic precursor cell aggregates into functional islet-like clusters when encapsulated within a three-dimensional hydrogel. Undifferentiated pancreatic precursor cells were isolated from E.15 rat embryos, dissociated into single cells, and aggregated in suspension-rotation culture. Aggregates were photoencapsulated into poly(ethylene glycol) hydrogels with entrapped collagen type 1 and cultured for 14 days with or without a gamma-secretase inhibitor. Gene expression, proinsulin content, and C-peptide release were measured to determine differentiation and maturation of encapsulated precursor cell aggregates. In the control medium, scattered breakthrough beta cell differentiation was observed; however, cells remained largely insulin negative. Upon addition of a gamma-secretase inhibitor the majority of cells in clusters became insulin positive, and insulin per DNA and glucose-stimulated insulin release measurements for these cultures were comparable with those for adult rat islets. Cluster counts after culture day 14 were 88% of those initially encapsulated, demonstrating excellent cluster survival in hydrogel culture. These results indicate that concerted differentiation of pancreatic precursor cell aggregates into functionally mature islet-like clusters can be achieved in poly(ethylene glycol)-based hydrogel cultures by blocking cell contact-mediated Notch signaling with a gamma-secretase inhibitor.

The administration of BDNF and GDNF to the brain via PLGA microparticles patterned within a degradable PEG-based hydrogel: Protein distribution and the glial response

Tailored delivery of neurotrophic factors (NFs) is a critical challenge that continues to inhibit strategies for guidance of axonal growth in vivo. Of particular importance is the ability to recreate innervation of distant brain regions by transplant tissue, for instance rebuilding the nigrostriatal track, one focus in Parkinson's disease research. Many strategies have utilized polymer drug delivery to target NF release in space and time, but combinatorial approaches are needed to deliver multiple NFs at relevant therapeutic times and locations without toxic side effects. Here we engineered a paradigm of PLGA microparticles entrapped within a degradable PEG-based hydrogel device to locally release two different types of NFs with two different release profiles. Hydrogel/microparticle devices were developed and analyzed for their ability to release GDNF in the caudal area of the brain, near the substantia nigra, or BDNF in the rostral area, near the striatum. The devices delivered their respective NFs in a region localized to within 100 μm of the bridge, but not exclusively to the targeted rostral or caudal ends. BDNF was slowly released over a 56-day period, whereas a bolus of GDNF was released around 28 days. The timed delivery of NFs from implanted devices significantly reduced the microglial response relative to sham surgeries. Given the coordinated drug delivery ability and reduced localized inflammatory response, this multifaceted PEG hydrogel/PLGA microparticle strategy may be a useful tool for further development in combining tissue engineering and drug delivery, and recreating the nigrostriatal track.

A novel composite construct increases the vascularization potential of PEG hydrogels through the incorporation of large fibrin ribbons

Developing a mechanism to vascularize tissue-engineered constructs is imperative for transplant function and integration, particularly when delivering hypoxia-sensitive tissues, such as pancreatic islets. Previous efforts have focused on bulk modifications of scaffold materials rendering the entire construct permissive to vessel penetration or the formation of a porous structure where vessels can infiltrate the empty spaces. Here, we describe a novel construct composed of large fibrin ribbons encapsulated within a poly(ethylene glycol) (PEG) hydrogel. The PEG/fibrin ribbon composite scaffold facilitates coculture of adhesive and nonadhesive cell types, thus providing closely neighboring environments with distinct material properties specific to the needs of two clinically relevant cell populations. This advantage is demonstrated here by the successful coculture of pancreatic islets in the PEG component and vessel-forming endothelial cells in entrapped fibrin ribbons. Transplanted endothelial cells can form anastomosies with host vasculature, suggesting that our cocultures may lead to more rapid scaffold vascularization. Additionally, we show that surface-seeded endothelial cells form multicellular projections that migrate into nonadhesive PEG hydrogels along permissive fibrin ribbons, further demonstrating composite construct vascularization potential. Distribution of large fibrin ribbons throughout PEG hydrogels provide a potential mechanism for vascularization of a well-established biomaterial without inherently changing its desirable properties.

Effect of macromer weight percent on neural cell growth in 2D and 3D nondegradable PEG hydrogel culture

Neural precursor cells (NPCs) are a renewable cell source that may be useful for neural cell transplant therapies. Their expansion and differentiation potential have traditionally been explored by culturing them on stiff tissue culture polystyrene. Here we describe advantages of an alternative culture system: bio-inert poly(ethylene glycol) (PEG) hydrogels. Specifically this work reports the effect that macromer weight percent has on the metabolic and apoptotic activity, proliferation, and cellular composition of a mixed population of neurons and multipotent NPCs grown both on 2D and within 3D PEG hydrogels. In 2D culture, hydrogel properties did not affect metabolic or apoptotic activity but did impact cell proliferation and composition leading to an increase in glial cell reactivity as stiffness increased. In 3D culture, low weight percent hydrogels led to greater metabolic activity and lower apoptotic activity with significant proliferation observed only in hydrogels that closely matched the stiffness of native brain tissue. PEG hydrogels therefore provide a versatile in vitro culture system that can be used to culture and expand a variety of neural and glial cell types simply by altering the material properties of the hydrogel.

Trophic factors GDNF and BDNF improve function of retinal sheet transplants

The aim of this study was to compare glial-derived neurotrophic factor (GDNF) treatment with brain-derived neurotrophic factor (BDNF) treatment of retinal transplants on restoration of visual responses in the superior colliculus (SC) of the S334ter line 3 rat model of rapid retinal degeneration (RD). RD rats (age 4-6 weeks) received subretinal transplants of intact sheets of fetal retina expressing the marker human placental alkaline phosphatase (hPAP). Experimental groups included: (1) untreated retinal sheet transplants, (2) GDNF-treated transplants, (3) BDNF-treated transplants, (4) none surgical, age-matched RD rats, (5) sham surgery RD controls, (6) progenitor cortex transplant RD controls, and (7) normal pigmented rat controls. At 2-8 months after transplantation, multi-unit visual responses were recorded from the SC using a 40 ms full-field stimulus (-5.9 to +1 log cd/m(2)) after overnight dark-adaptation. Responses were analyzed for light thresholds, spike counts, response latencies, and location within the SC. Transplants were grouped into laminated or rosetted (more disorganized) transplants based on histological analysis. Visual stimulation of control RD rats evoked no responses. In RD rats with retinal transplants, a small area of the SC corresponding to the position of the transplant in the host retina, responded to light stimulation between -4.5 and -0.08 log cd/m(2), whereas the light threshold of normal rats was at or below -5 log cd/m(2) all over the SC. Overall, responses in the SC in rats with laminated transplants had lower response thresholds and were distributed over a wider area than rats with rosetted transplants. BDNF treatment improved responses (spike counts, light thresholds and responsive areas) of rats with laminated transplants whereas GDNF treatment improved responses from rats with both laminated and rosetted (more disorganized) transplants. In conclusion, treatment of retinal transplants with GDNF and BDNF improved the restoration of visual responses in RD rats; and GDNF appears to exert greater overall restoration than BDNF.

Impact of degradable macromer content in a poly(ethylene glycol) hydrogel on neural cell metabolic activity, redox state, proliferation, and differentiation

Hydrogels that degrade at different rates were prepared by copolymerizing slowly degrading macromer poly(ethylene glycol) (PEG) dimethacrylate with a faster degrading macromer poly(lactic acid)-b-PEG-b-poly(lactic acid) dimethacrylate. A clinically relevant population of neural cells composed of differentiated neurons and multipotent precursor cells was cultured within hydrogels. Within 2 h after encapsulation, metabolic activity was higher in hydrogels prepared with increasing levels of degradable content. This improvement was accompanied by a reduction in intracellular redox state and an increase in the fraction of glutathione in the reduced state, both of which persisted throughout 7 days of culture and which may be the result of radical scavenging by lactic acid. Importantly, an increase in cellular proliferation was observed in gels prepared with increasing degradable macromer content after 7 days of growth without a shift in the cellular composition of the culture toward the glial cell phenotype. The findings of this study provide additional insight into the growth of neural cells in PEG-based hydrogels. Results suggest that lactic acid released during gel degradation may impact the function of encapsulated cells, a finding of general interest to biomaterials scientists who focus on the development of degradable polymers for cell culture and drug delivery devices.

PEGylation of interleukin-10 for the mitigation of enhanced pain states

The anti-inflammatory cytokine interleukin-10 (IL-10) shows promise for the treatment of neuropathic pain, but for IL-10 to be clinically useful as a short-term therapeutic its duration needs to be improved. In this study, IL-10 was covalently modified with polyethylene glycol (PEG) with the goal of stabilizing and increasing protein levels in the CSF to improve the efficacy of IL-10 for treating neuropathic pain. Two different PEGylation methods were explored in vitro to identify suitable PEGylated IL-10 products for subsequent in vivo testing. PEGylation of IL-10 by acylation yielded a highly PEGylated product with a 35-fold in vitro biological activity reduction. PEGylation of IL-10 by reductive amination yielded products with a minimal number of PEG molecules attached and in vitro biological activity reductions of approximately 3-fold. In vivo collections of cerebrospinal fluid after intrathecal administration demonstrated that 20 kDa PEG attachment to IL-10 increased the concentration of IL-10 in the cerebrospinal fluid over time. Relative to unmodified IL-10, the 20 kDa PEG-IL-10 product exhibited an increased therapeutic duration and magnitude in an animal model of neuropathic pain. This suggests that PEGylation is a viable strategy for the short-term treatment or, in conjunction with other approaches, the long-term treatment of enhanced pain states.

Central nervous system delivery of large molecules: challenges and new frontiers for intrathecally administered therapeutics

IMPORTANCE OF THE FIELD

Therapeutic proteins and DNA constructs offer promise for the treatment of central nervous system disorders, yet significant biological barriers limit the ability of these molecules to reach the central nervous system from the bloodstream. Direct administrations to the cerebrospinal fluid (intrathecal administration) comprise an emerging field to facilitate the efficient delivery of these biological macromolecules to central nervous system tissues.

AREAS COVERED IN THIS REVIEW

Previous reports from 1990 to the present time describing the interactions and turnover of the cerebrospinal fluid within the intrathecal space, characterizations of the effects that therapeutic proteins and DNA have shown after intrathecal delivery through a lumbar route, and reports of emerging technologies to address the limitations of intrathecally administered macromolecules are reviewed.

WHAT THE READER WILL GAIN

This review provides an overview of the limitations that must be overcome for intrathecally administered biological macromolecules and the recent advances and promising approaches for surmounting these limitations.

TAKE HOME MESSAGE

Emerging approaches that stabilize and sustain the delivery of intrathecally administered biological macromolecules may enhance substantially the clinical relevance of promising therapeutic proteins and DNA constructs for the treatment of various central nervous system disorders.

Release of plasmid DNA-encoding IL-10 from PLGA microparticles facilitates long-term reversal of neuropathic pain following a single intrathecal administration

PURPOSE

Interleukin-10 (IL-10) is an anti-inflammatory molecule that has achieved interest as a therapeutic for neuropathic pain. In this work, the potential of plasmid DNA-encoding IL-10 (pDNA-IL-10) slowly released from biodegradable microparticles to provide long-term pain relief in an animal model of neuropathic pain was investigated.

METHODS

PLGA microparticles encapsulating pDNA-IL-10 were developed and assessed both in vitro and in vivo.

RESULTS

In vitro, pDNA containing microparticles activated macrophages, enhanced the production of nitric oxide, and increased the production of IL-10 protein relative to levels achieved with unencapsulated pDNA-IL-10. In vivo, intrathecally administered microparticles embedded in meningeal tissue, induced phagocytic cell recruitment to the cerebrospinal fluid, and relieved neuropathic pain for greater than 74 days following a single intrathecal administration, a feat not achieved with unencapsulated pDNA. Therapeutic effects of microparticle-delivered pDNA-IL-10 were blocked in the presence of IL-10-neutralizing antibody, and elevated levels of plasmid-derived IL-10 were detected in tissues for a prolonged time period post-injection (>28 days), demonstrating that therapeutic effects are dependent on IL-10 protein production.

CONCLUSIONS

These studies demonstrate that microparticle encapsulation significantly enhances the potency of intrathecally administered pDNA, which may be extended to treat other disorders that require intrathecal gene therapy.

PEGylation of brain-derived neurotrophic factor for preserved biological activity and enhanced spinal cord distribution

Brain-derived neurotrophic factor (BDNF) was covalently attached to polyethylene glycol (PEG) in order to enhance delivery to the spinal cord via the cerebrospinal fluid (intrathecal administration). By varying reaction conditions, mixtures of BDNF covalently attached to one (primary), two (secondary), three (tertiary), or more (higher order) PEG molecules were produced. The biological activity of each resulting conjugate mixture was assessed with the goal of identifying a relationship between the number of PEG molecules attached to BDNF and biological activity. A high degree of in vitro biological activity was maintained in mixtures enriched in primary and secondary conjugate products, while a substantial reduction in biological activity was observed in mixtures with tertiary and higher order conjugates. When a biologically active mixture of PEG-BDNF was administered intrathecally, it displayed a significantly improved half-life in the cerebrospinal fluid and an enhanced penetration into spinal cord tissue relative to native BDNF. Results from these studies suggest a PEGylation strategy that preserves the biological activity of the protein while also improving the half-life of the protein in vivo. Furthermore, PEGylation may be a promising approach for enhancing intrathecal delivery of therapeutic proteins with potential for treating disease and injury in the spinal cord.

Entrapped collagen type 1 promotes differentiation of embryonic pancreatic precursor cells into glucose-responsive beta-cells when cultured in three-dimensional PEG hydrogels

Development of an alternative source of functional, transplantable beta-cells to replace or supplement cadaveric tissue is critical to the future success of islet cell transplantation therapy. Embryonic pancreatic precursor cells are desirable as a renewable source of beta-cells as they are both proliferative and inherently capable of pancreatic cell differentiation. We have previously shown that precursor cells undergo selective beta-cell differentiation when dissociated and photoencapsulated in a polyethylene glycol (PEG) hydrogel network; however, these cells remained immature and were not glucose responsive. Collagen type 1 supports mature cell viability and function in many cell types and we hypothesized that incorporating it within our gels may support differentiating beta-cells and facilitate beta-cell maturation. For these studies, collagen-1 was entrapped with dissociated pancreatic precursor cells in a PEG hydrogel matrix (PEGCol) with the following key findings: (1) mature, glucose-responsive, islet-like structures differentiated from spontaneously forming precursor cell clusters in PEGCol, but not unmodified PEG, hydrogels; (2) a balance existed between providing sufficient collagen-1 signaling to support precursor cell development and providing an overabundance of adhesive sites allowing contaminating mesenchymal cells to thrive' and (3) mechanical stability provided by the PEG hydrogel platform is important for successful precursor cell culture, as PEGCol hydrogels encourage glucose responsiveness and high-insulin gene expression, while pure collagen gel cultures, with the same collagen concentration, have negligible insulin gene expression. These results indicate that PEGCol hydrogels are a useful culture platform to promote differentiation of a glucose-responsive beta-cell population from dissociated precursor cells.

Selective beta-cell differentiation of dissociated embryonic pancreatic precursor cells cultured in synthetic polyethylene glycol hydrogels

Continuing advances in islet cell transplantation have been promising; however, several limitations, including severe shortage of transplantable islets, hinder the widespread use of this therapy. Pancreatic precursor cells are one alternative to cadaveric donor islets. These cells found in the developing pancreatic buds are capable of self-renewal and also have the innate ability to become insulin-producing beta-cells. For this work, bioinert polyethylene glycol (PEG) hydrogels were chosen as the supportive three-dimensional matrix for encapsulation of dissociated pancreatic precursor cells obtained from the dorsal pancreatic bud of day-15 rat embryos. This culture system was selected in order to eliminate cell-extracellular matrix and cell-cell signal heterogeneity present when intact pancreatic buds are embedded in protein-based gels, the typical in vitro culture conditions used to study this cell population. In this study it was found that (1) dissociated precursor cells maintain a robust viability for 7 days in PEG hydrogel culture, (2) encapsulated cells selectively differentiate into insulin-expressing beta-cells, and (3) differentiated beta-cells have releasable insulin stores, but are not achieving a mature, glucose responsive phenotype. These findings suggest that encapsulating dissociated pancreatic precursor cells in an environment designed to minimize the heterogeneous signaling cues present during development or in standard culture conditions generates a population highly enriched in pancreatic beta-cells; however, future efforts must focus on achieving glucose responsiveness in this cell population. Further, these results indicate that differentiation down a beta-cell lineage may be the default pathway in pancreatic development.

Impact of lactic acid on cell proliferation and free radical-induced cell death in monolayer cultures of neural precursor cells

Biomaterials prepared from polyesters of lactic acid and glycolic acid, or a mixture of the two, degrade in the presence of water into the naturally occurring metabolites, lactic acid and glycolic acid. While the lactic acid degradation product that is released from biomaterials is well tolerated by the body, lactic acid can influence the metabolic function of cells; it can serve as an energy substrate for cells, and has been shown to have antioxidant properties. Neural precursor cells, a cell population of considerable interest as a source of cells for neural tissue regeneration strategies, generate a high amount of reactive oxygen species, and when associated with a degradable biomaterial, may be impacted by released lactic acid. In this work, the effect of lactic acid on a neural cell population containing proliferative neural precursor cells was examined in monolayer culture. Lactic acid was found to scavenge exogenously added free radicals produced in the presence of either hydrogen peroxide or a photoinitiator (I2959) commonly utilized in the preparation of photopolymerizable biomaterials. In addition to its effect on exogenously added free radicals, lactic acid reduced intracellular redox state, increased the proliferation of the cell population, and modified the cell composition. The findings of this study provide insight into the role that lactic acid plays naturally on developing neural cells and are also of interest to biomaterials scientists that are focused on the development of degradable lactic-acid-based polymers for cell culture devices. The effect of lactic acid on other cell populations may differ and should be characterized to best understand how cells function in degradable cell culture devices.

Long-term control of neuropathic pain in a non-viral gene therapy paradigm

Traditional approaches to treating chronic neuropathic pain largely focus on manipulations directly altering neuronal activity or neuron-to-neuron communication. Recently, however, it has become clear that glial cells (including microglia and astroglia) play a significant role in pain expression in a variety of neuropathic pain models. Multiple aspects of the inflammatory response of glial cells, commonly observed in neuropathic pain conditions, have been implicated in pain expression. Thus, glial cell inflammation has emerged as a potential therapeutic target in neuropathic pain. Our laboratory has been exploring the use of an anti-inflammatory cytokine, interleukin-10 (IL-10), to control glial inflammatory activation thereby controlling neuropathic pain. IL-10 protein delivery is limited by a short half-life and an inability to cross into the central nervous system from the periphery, making a centrally delivered gene therapy approach attractive. We have recently characterized a non-viral gene therapy approach using two injections of naked DNA to achieve long-term (>3 months) control of neuropathic pain in a peripheral nerve injury model. Timing and dose requirements leading to long-term pain control are discussed in this review, as is recent work using microparticle-encapsulated DNA to achieve long-term therapeutic efficacy with a single injection.

Biocompatibility of PEG-based hydrogels in primate brain

Degradable polymers have been used successfully in a wide variety of peripheral applications from tissue regeneration to drug delivery. These polymers induce little inflammatory response and appear to be well accepted by the host environment. Their use in the brain, for neural tissue reconstruction or drug delivery, also could be advantageous in treating neurodegenerative disorders. Because the brain has a unique immune response, a polymer that is compatible in the body may not be so in the brain. In the present study, polyethylene glycol (PEG)-based hydrogels were implanted into the striatum and cerebral cortex of nonhuman primates. Four months after implantation, brains were processed to evaluate the extent of astrogliosis and scaring, the presence of microglia/macrophages, and the extent of T-cell infiltration. Hydrogels with 20% w/v PEG implanted into the brain stimulated a slight increase in astrocytic and microglial/macrophage presence, as indicated by a small increase in glial fibrillary acidic protein (GFAP) and CD68 staining intensity. This increase was not substantially different from that found in the sham-implanted hemispheres of the brain. Staining for CD3+ T cells indicated no presence of peripheral T-cell infiltration. No gliotic scarring was seen in any implanted hemisphere. The combination of low density of GFAP-positive cells and CD68-positive cells, the absence of T cells, and the lack of gliotic scarring suggest that this level of immune response is not indicative of immunorejection and that the PEG-based hydrogel has potential to be used in the primate brain for local drug delivery or neural tissue regeneration.

BDNF-treated retinal progenitor sheets transplanted to degenerate rats: improved restoration of visual function

The aim of this study was to evaluate the functional efficacy of retinal progenitor cell (RPC) containing sheets with BDNF microspheres following subretinal transplantation in a rat model of retinal degeneration. Sheets of E19 RPCs derived from human placental alkaline phosphatase (hPAP) expressing transgenic rats were coated with poly-lactide-co-glycolide (PLGA) microspheres containing brain-derived neurotrophic factor (BDNF) and transplanted into the subretinal space of S334ter line 3 rhodopsin retinal degenerate rats. Controls received transplants without BDNF or BDNF microspheres alone. Visual function was monitored using optokinetic head-tracking behavior. Visually evoked responses to varying light intensities were recorded from the superior colliculus (SC) by electrophysiology at 60days after surgery. Frozen sections were studied by immunohistochemistry for photoreceptor and synaptic markers. Visual head tracking was significantly improved in rats that received BDNF-coated RPC sheets. Relatively more BDNF-treated transplanted rats (80%) compared to non-BDNF transplants (57%) responded to a "low light" intensity of 1cd/m2 in a confined SC area. With bright light, the onset latency of SC responses was restored to a nearly normal level in BDNF-treated transplants. No significant improvement was observed in the BDNF-only and no surgery transgenic control rats. The bipolar synaptic markers mGluR6 and PSD-95 showed normal distribution in transplants and abnormal distribution of the host retina, both with or without BDNF treatment. Red-green cones were significantly reduced in the host retina overlying the transplant in the BDNF-treated group. In summary, BDNF coating improved the functional efficacy of RPC grafts. The mechanism of the BDNF effects--either promoting functional integration between the transplant and the host retina and/or synergistic action with other putative humoral factors released by the RPCs--still needs to be elucidated.

A new subtype of brachydactyly type B caused by point mutations in the bone morphogenetic protein antagonist NOGGIN

Brachydactyly type B (BDB) is characterized by terminal deficiency of fingers and toes, which is caused by heterozygous truncating mutations in the receptor tyrosine kinase-like orphan receptor 2 (ROR2) in the majority of patients. In a subset of ROR2-negative patients with BDB, clinically defined by the additional occurrence of proximal symphalangism and carpal synostosis, we identified six different point mutations (P35A, P35S, A36P, E48K, R167G, and P187S) in the bone morphogenetic protein (BMP) antagonist NOGGIN (NOG). In contrast to previously described loss-of-function mutations in NOG, which are known to cause a range of conditions associated with abnormal joint formation but without BDB, the newly identified BDB mutations do not indicate a major loss of function, as suggested by calculation of free-binding energy of the modeled NOG-GDF5 complex and functional analysis of the micromass culture system. Rather, they presumably alter NOG's ability to bind to BMPs and growth-differentiation factors (GDFs) in a subtle way, thus disturbing the intricate balance of BMP signaling. The combined features observed in this phenotypic subtype of BDB argue for a functional connection between BMP and ROR2 signaling and support previous findings of a modulating effect of ROR2 on the BMP-receptor pathway through the formation of a heteromeric complex of the receptors at the cell surface.

Contrasting effects of collagen and bFGF-2 on neural cell function in degradable synthetic PEG hydrogels

Injectable biodegradable cell carriers provide a potential means to improve transplanted cell viability in the nervous system by providing physical protection from compaction, shear forces, and the acute inflammatory response that occurs following transplantation into the host brain environment. Synthetic polyethylene glycol (PEG) hydrogels are ideal candidates for this purpose, as the degradation profile and mechanical properties of the gel can be controlled. Here we introduce biological components into the synthetic gel with the goal of improving neural cell function in the inert PEG environment. In this study, it was found that (1) bFGF-2 is a survival/mitogenic factor for neural precursor cells in degradable hydrogel cultures, (2) collagen has no measurable effect on cell survival, metabolic activity, or proliferation, and (3) co-application of collagen and bFGF-2 to hydrogel cultures targets cell survival and metabolic activity, an effect that is different than either applied individually. Because collagen and bFGF-2 support the survival and growth of neural cells and other cell types, the co-encapsulation approach and functional characterization described in this study can be extended to the development of an array of tissue engineering applications. These findings suggest the importance of understanding and developing strategies to control the chemical microenvironment surrounding cells in three-dimensional biomaterials.

Intrathecal polymer-based interleukin-10 gene delivery for neuropathic pain

Research on communication between glia and neurons has increased in the past decade. The onset of neuropathic pain, a major clinical problem that is not resolved by available therapeutics, involves activation of spinal cord glia through the release of proinflammatory cytokines in acute animal models of neuropathic pain. Here, we demonstrate for the first time that the spinal action of the proinflammatory cytokine, interleukin 1 (IL-1) is involved in maintaining persistent (2 months) allodynia induced by chronic-constriction injury (CCI). The anti-inflammatory cytokine IL-10 can suppress proinflammatory cytokines and spinal cord glial amplification of pain. Given that IL-1 is a key mediator of neuropathic pain, developing a clinically viable means of long-term delivery of IL-10 to the spinal cord is desirable. High doses of intrathecal IL-10-gene therapy using naked plasmid DNA (free pDNA-IL-10) is effective, but the dose required limits its potential clinical utility. Here we show that intrathecal gene therapy for neuropathic pain is improved sufficiently using two, distinct synthetic polymers, poly(lactic-co-glycolic) and polyethylenimine, that substantially lower doses of pDNA-IL-10 are effective. In conclusion, synthetic polymers used as i.t. gene-delivery systems are well-tolerated and improve the long-duration efficacy of pDNA-IL-10 gene therapy.

Environmental cues to guide stem cell fate decision for tissue engineering applications

The human body contains a variety of stem cells capable of both repeated self-renewal and production of specialised, differentiated progeny. Critical to the implementation of these cells in tissue engineering strategies is a thorough understanding of which external signals in the stem cell microenvironment provide cues to control their fate decision in terms of proliferation or differentiation into a desired, specific phenotype. These signals must then be incorporated into tissue regeneration approaches for regulated exposure to stem cells. The precise spatial and temporal presentation of factors directing stem cell behaviour is extremely important during embryogenesis, development and natural healing events, and it is possible that this level of control will be vital to the success of many regenerative therapies. This review covers existing tissue engineering approaches to guide the differentiation of three disparate stem cell populations: mesenchymal, neural and endothelial. These progenitor cells will be of central importance in many future connective, neural and vascular tissue regeneration technologies.

Impact of cell type and density on nerve growth factor distribution and bioactivity in 3-dimensional collagen gel cultures

Local delivery of protein agents is potentially important in many tissue engineering systems. In this report, we evaluate an experimental system for measuring the rate of nerve growth factor (NGF) transport and biological activity within a 3-dimensional, tissue-like environment. Fetal brain cells or PC12 cells were suspended throughout collagen gel cultures; controlled-release matrices were used to control the spatial and temporal pattern of NGF release. Experimentally measured concentration profiles were compared to profiles predicted by a mathematical model encompassing diffusion and first-order elimination. Our results suggest that NGF moves through gels by diffusion while being eliminated at a rate that depends on cell density. Since diffusion and elimination also govern protein transport in brain tissue, the collagen gel serves as a model system that replicates the main features of transport in the brain and, therefore, can be used to identify new strategies that enhance NGF distribution in the central nervous system. As an example of the utility of this biophysical model, we demonstrate that implantation of multiple controlled-release matrices can broaden NGF distribution in gel cultures; this broadening was accompanied by a significant increase in cellular biological activity. This approach may be useful in customizing NGF distribution throughout degenerating or damaged central nervous system tissue while minimizing toxicity to surrounding healthy tissue.

Three-dimensional growth and function of neural tissue in degradable polyethylene glycol hydrogels

Graft survival and integration are major factors that limit the efficacy of cell therapies for the treatment of disease and injury in the central nervous system. Efforts to improve cell survival and integration have focused in part on the development of biocompatible scaffolds that support neural cell growth and function. Here we photoencapsulate neural cells within degradable hydrogels and use confocal microscopy to non-invasively monitor these key cell functions over time. By directly imaging fluorescently labeled cells we show that neural cells cultured within three-dimensional polymer networks create their own cellular microenvironment to survive, proliferate and differentiate and form neurons and glia that are electrophysiologically responsive to neurotransmitter. By changing the degradation rate of the polymer network, the time-scale over which neural cells extend processes throughout the hydrogel could be tuned on a time-scale that ranged from 1-3 weeks. These studies were carried out in the absence of serum and extracellular matrix molecules that can be immunogenic and identify degradable PEG hydrogels as suitable synthetic cell carriers for neural transplantation.

The influence of microchannels on neurite growth and architecture

Microchannels were produced using a photolithographic technique to pattern polyimide walls (11 microm in height and 20-60 microm in width) onto a planar glass substrate. PC12 cells were seeded onto patterned surfaces. After 3 days of culture in NGF supplemented medium cells were viable and extended neurites. Culture in microchannels influenced the direction of neurite growth (theta Orientation) and the complexity of PC12 cell architecture including neurite length (L(Neurite)), the number of neurites emerging per cell (N(Neurites)), and the angle at which neurites emerged from the cell soma (theta Soma). In microchannels neurites oriented parallel to channel walls and the complexity of neuronal architecture was reduced. Both of these effects were strongest for cells located in channels 20-30 microm wide. Within each channel the magnitude of the effect on orientation and architecture was inversely proportional to the distance of the soma from the channel wall. Microtubule and actin filament mobility within the cytoplasm may underly effect on neurite orientation and cell architecture. By manipulating channel width the overall direction of neurite growth and the complexity of neuronal architecture was controlled. Results from these studies will be applied towards the development of biomaterials for microfluidic platforms and drug discovery studies and in neural regeneration research-two applications that would be significantly improved given the ability to control neurite orientation and the complexity of neuronal architecture.

Late first-trimester invasive prenatal diagnosis: results of an international randomized trial

OBJECTIVE

To assess, in a randomized trial, the safety and accuracy of amniocentesis and transabdominal chorionic villus sampling (CVS) performed at 11-14 weeks of gestation, given that this time frame is increasingly relevant to early trisomy screening.

METHODS

We compared amniocentesis with CVS from 77 to 104 days of gestation in a randomized trial in a predominantly advanced maternal age population. Before randomization, the feasibility of both procedures was confirmed by ultrasonography, and experienced operators performed sampling under ultrasound guidance; conventional cytogenetic analysis was employed. The primary outcome measure was a composite of fetal loss plus preterm delivery before 28 weeks of gestation in cytogenetically normal pregnancies.

RESULTS

We randomized 3,775 women into 2 groups (1,914 to CVS; 1,861 to amniocentesis), which were comparable at baseline. More than 99.6% had the assigned procedure, and 99.9% were followed through delivery. In contrast to previous thinking, in the cytogenetically normal cohort (n = 3,698), no difference in primary study outcome was observed: 2.1% (95% confidence interval 1.5, 2.8) for CVS and 2.3% (95% confidence interval, 1.7, 3.1) for amniocentesis. However, spontaneous losses before 20 weeks and procedure-related, indicated terminations combined were increased in the amniocentesis group (P =.07, relative risk 1.74). We found a 4-fold increase in the rate of talipes equinovarus after amniocentesis (P =.02) overall and in week 13 (P =.03, relative risk = 4.65), but data were insufficient to determine this risk in week 14.

CONCLUSION

Amniocentesis at 13 weeks carries a significantly increased risk of talipes equinovarus compared with CVS and also suggests an increase in early, unintended pregnancy loss.

LEVEL OF EVIDENCE

I

Quantifying Stratospheric Ozone in the Upper Troposphere with in Situ Measurements of HCl

We have developed a chemical ionization mass spectrometry technique for precise in situ measurements of hydrochloric acid (HCl) from a high-altitude aircraft. In measurements at subtropical latitudes, minimum HCl values found in the upper troposphere (UT) were often near or below the detection limit of the measurements (0.005 parts per billion by volume), indicating that background HCl values are much lower than a global mean estimate. However, significant abundances of HCl were observed in many UT air parcels, as a result of stratosphere-to-troposphere transport events. We developed a method for diagnosing the amount of stratospheric ozone in these UT parcels using the compact linear correlation of HCl with ozone found throughout the lower stratosphere (LS). Expanded use of this method will lead to improved quantification of cross-tropopause transport events and validation of global chemical transport models.

Transplantation of brain cells assembled around a programmable synthetic microenvironment

Cell therapy is a promising method for treatment of hematopoietic disorders, neurodegenerative diseases, diabetes, and tissue loss due to trauma. Some of the major barriers to cell therapy have been partially addressed, including identification of cell populations, in vitro cell proliferation, and strategies for immunosuppression. An unsolved problem is recapitulation of the unique combinations of matrix, growth factor, and cell adhesion cues that distinguish each stem cell microenvironment, and that are critically important for control of progenitor cell differentiation and histogenesis. Here we describe an approach in which cells, synthetic matrix elements, and controlled-release technology are assembled and programmed, before transplantation, to mimic the chemical and physical microenvironment of developing tissue. We demonstrate this approach in animals using a transplantation system that allows control of fetal brain cell survival and differentiation by pre-assembly of neo-tissues containing cells and nerve growth factor (NGF)-releasing synthetic particles.

Ratio of nuchal thickness to humerus length for Down syndrome detection

OBJECTIVE

Ultrasonographic biometry markers are now being used clinically to adjust Down syndrome risk. The limitations are that the definitions of "abnormal" measurements used are arbitrary, thus reducing screening performance, and also that patient-specific Down syndrome risks cannot be calculated. We report a new ultrasonographic algorithm that is sensitive for Down syndrome detection and that estimates individual risk.

STUDY DESIGN

Overall in fetal populations with Down syndrome the humerus length is decreased, whereas the nuchal thickness is increased relative to that of a normal population. The nuchal thickness/humerus length ratio therefore shows an even greater increase and magnifies the separation between Down syndrome and healthy groups. Prospective data were collected in midtrimester amniocentesis cases. A regression equation for the median nuchal thickness/humerus length ratio based on biparietal partial diameter was generated. The Down syndrome likelihood ratio, or the odds on the basis of the nuchal thickness/humerus length ratio (multiples of the median), was multiplied by the age-related risk to give the posterior Down syndrome risk. Charts for rapid estimation of individual Down syndrome risk on the basis of maternal age and the nuchal thickness/humerus length ratio were constructed.

RESULTS

There were 94 cases of Down syndrome and 4700 cases in which the karyotype was normal. The mean (+/-SD) gestational age of the study population was 16.1 +/- 1.6 weeks. Thirty-three fetuses with Down syndrome and 68 karyotypically normal fetuses had gross anomalies. The equation for the expected median nuchal thickness/humerus length ratio was as follows: 10e(1.7163 - 0.0292) x BPD + 0.0003 x BPD2, where BPD is the biparietal diameter. In the overall study population the nuchal thickness/humerus length ratio and maternal age had a 79.8% detection rate at a 22.1% false-positive rate, compared with maternal age plus humerus length (sensitivity, 55.1%) or maternal age plus nuchal thickness (sensitivity, 66.7%) at the same false-positive rate. For women > or =35 years old the values were 80% and 22.0%, respectively.

CONCLUSIONS

We report an ultrasonographic biometry algorithm that, in combination with maternal age, detects 79.6% of Down syndrome cases in a high-risk group. Individual Down syndrome risk can be quickly calculated at the bedside and made available to women who desire this information before making a decision on amniocentesis. On the basis of published standards, ultrasonographic biometry as described would be a cost-effective alternative to amniocentesis in this high-risk group.

Molecular systematics of Plethodon and Aneides (Caudata: Plethodontidae: Plethodontini): phylogenetic analysis of an old and rapid radiation

The closely related salamander genera Plethodon and Aneides (Plethodontidae) differ in morphology, behavior, and ecology. Although the systematics of these taxa has been the focus of much study, many details remain unresolved. To generate an hypothesis for the relationships among these taxa, I sequenced a segment of the mitochondrial protein-coding gene ND4 and portions of mitochondrial tRNAs. Taxa sampled were 5 species of Aneides, 7 species of western Plethodon, and 13 species of eastern Plethodon. Ensatina eschscholtzii was used as the outgroup. Phylogenetic analyses using maximum-parsimony, neighbor-joining, and maximum-likelihood consistently recovered some relationships. The eastern species of Plethodon are a robust, well-supported clade. Sister taxon relationships of P. elongatus and P. stormi, of P. dunni and P. vehiculum, and of A. hardii and the three west coast species of Aneides were also consistently resolved with good support. The monophyly of Aneides was only weakly supported in some analyses and there is no evidence for the monophyly of Plethodon or of the western species of Plethodon. Excluding the relatively distant outgroup, down-weighting saturated substitutions, and analyzing conserved data partitions did not yield additional resolution or support among the lineages of western Plethodon and Aneides. These results are consistent either with saturation of sequences, due to the age of the lineages, or with relatively rapid radiation. An old, rapid radiation is consistent with the results of previous studies. An analysis of current taxonomy within the phylogenetic framework presented here retains Aneides and recognizes Plethodon as a metataxon (indicated with an asterisk, Plethodon*).

Comparison of urinary hyperglycosylated human chorionic gonadotropin concentration with the serum triple screen for Down syndrome detection in high-risk pregnancies

OBJECTIVE

Both modest screening performance and declining patient and physician acceptance have stimulated interest in alternative markers to the triple screen for the detection of Down syndrome. Our purpose was to compare the concentration of a single urinary analyte, hyperglycosylated human chorionic gonadotropin, with the serum triple screen (alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol concentrations combined with age) for second-trimester Down syndrome detection.

STUDY DESIGN

Urine and blood were obtained from pregnant women in the second trimester undergoing genetic amniocentesis. Urinary hyperglycosylated human chorionic gonadotropin concentration and serum triple-screen values were measured. Individuals undergoing amniocentesis because of abnormal triple-screen results were excluded. Individual Down syndrome risks on the basis of urinary hyperglycosylated human chorionic gonadotropin concentration plus maternal age and on the basis of the triple-screen results were calculated. For each algorithm the sensitivity and false-positive rate for Down syndrome detection at different risk thresholds were determined. From these values receiver operating characteristic curves were constructed, and the area under the curve was determined for each algorithm. Finally, the performance of a new combination in which urinary hyperglycosylated human chorionic gonadotropin concentration replaced serum human chorionic gonadotropin concentration in the triple screen was ascertained.

RESULTS

We studied 24 pregnancies complicated by Down syndrome and 500 unaffected pregnancies between 14 and 22 weeks' gestation in a mostly white (93.5%) population undergoing amniocentesis primarily because of advanced maternal age. The sensitivity and false-positive rate for urinary hyperglycosylated human chorionic gonadotropin concentration were 75. 0% and 5.6%, respectively, whereas those for the triple screen were 75.0% and 33.2%, respectively. Urinary hyperglycosylated human chorionic gonadotropin concentration was superior to the triple screen (area under the curve, 0.9337 vs 0.7887; P =.02). The substitution of urinary hyperglycosylated human chorionic gonadotropin concentration for serum human chorionic gonadotropin concentration in the triple screen resulted in a 91.7% sensitivity at a 10.0% false-positive rate, versus a 54.2% sensitivity for the traditional triple screen at the same false-positive rate.

CONCLUSION

The performance of urinary hyperglycosylated human chorionic gonadotropin concentration was statistically superior to that of the serum triple screen in a high-risk population. The use of urinary hyperglycosylated human chorionic gonadotropin concentration as an alternative test or substitution of this measurement for serum human chorionic gonadotropin concentration in the triple screen would improve diagnostic accuracy and address many current concerns related to the triple screen.

Combined ultrasound biometry, serum markers and age for Down syndrome risk estimation

OBJECTIVE

To compare Down syndrome screening efficiency of the standard serum triple analyte screen to that of a four-component screen consisting of ultrasound biometry and serum markers in the second trimester.

METHODS

The Down syndrome screening efficiency of the triple screen, i.e. alpha-fetoprotein (AFP), unconjugated estriol (E3), hCG and maternal age, was compared with the four-marker algorithm, i.e. humerus length, nuchal thickness, AFP and hCG plus maternal age. A quadrivariate Gaussian algorithm was used to calculate individual Down syndrome odds. Receiver operating characteristic (ROC) curves plotting sensitivity against false-positive rate were constructed for each algorithm and the areas under the curves were compared to determine which was superior. Sensitivity and false-positive rates at different Down syndrome risk thresholds were also compared.

RESULTS

There were 46 cases of Down syndrome (1.9%) with 2391 normal singleton pregnancies in a referral population in which triple screen, fetal biometry and karyotype had been done. The gestational age range for the study was 14-24 completed weeks. The median maternal age for the study group was 35.0 years (14.0-46.0 years). The areas (SE) under the ROC curves were 0.75(0.04) and 0.93(0.02) for the standard triple and the four-marker screen, respectively (P < 0.001). At a 10% false-positive rate, detection was 45.7% for the triple and 80.4% for the four-marker screen.

CONCLUSIONS

A new algorithm combining humerus length and nuchal thickness measurement with serum AFP, hCG and maternal age substantially improved Down syndrome screening efficiency compared with the traditional triple screen. The model appears promising and should be evaluated in an independent data set.

Cytogenetical diagnosis in paraffin-embedded fetoplacental tissue using comparative genomic hybridization

Comparative genomic hybridization (CGH) is a FISH-related technique used to assess global chromosomal aberrations in a variety of human tumours. Recently CGH has been applied to cytogenetic analysis of fresh frozen fetoplacental tissues. Here we report the application of CGH to paraffin-embedded placental samples. Ten samples from paraffin-embedded blocks of 6 control placentas and fetoplacental tissue from 10 aneuploidies, and 2 unbalanced aberrations were evaluated. Balanced karyotype profiles were obtained from samples of healthy placentas and all samples from the same placenta appeared to have similar confidence intervals. CGH analysis of four cases of trisomy 21, three cases of trisomy 18, one case of trisomy 13, one case of trisomy 15 and one case of trisomy 7 all showed overrepresentation of the respective trisomic chromosome. The CGH profile was also in accordance with the karyotyping of a case with isochromosome 21. The CGH profile of a case with der (2)t(2;6)(q37.3;q22.2) revealed partial trisomy for chromosome 6 between q21 and q27. CGH may be a useful adjunct in prenatal genetic diagnosis when retrospective diagnosis is needed from archival samples.

Hyperglycosylated human chorionic gonadotropin (invasive trophoblast antigen) immunoassay: A new basis for gestational Down syndrome screening

BACKGROUND

Serum human chorionic gonadotropin (hCG) and hCG free beta-subunit tests are used in combination with unconjugated estriol and alpha-fetoprotein in the triple screen test, and with the addition of inhibin-A in the quadruple marker test for detecting Down syndrome in the second trimester of pregnancy. These tests have a limited detection rate for Down syndrome: approximately 40% for hCG or free beta-subunit alone, approximately 60% for the triple screen test, and approximately 70% for the quadruple marker test, all at 5%, or a relatively high, false-positive rate. New tests are needed with higher detection and lower false rates. Hyperglycosylated hCG (also known as invasive trophoblast antigen or ITA) is a new test. It specifically detects a unique oligosaccharide variant of hCG associated with Down syndrome pregnancies. We evaluated this new Down syndrome-directed test in prenatal diagnosis.

METHODS

Hyperglycosylated hCG was measured in urine samples from women undergoing amniocentesis for advanced maternal age concerns at 14-22 weeks of gestation, 1448 with normal karyotype and 39 with Down syndrome fetuses.

RESULTS

The median hyperglycosylated hCG value was 9.5-fold higher in Down syndrome cases (9.5 multiples of the normal karyotype median). The single test detected 80% of Down syndrome cases at a 5% false-positive rate. Urine hyperglycosylated hCG was combined with urine beta-core fragment (urine breakdown product of serum hCG free beta-subunit), serum alpha-fetoprotein, and maternal age-related risk. This urine-serum combination detected 96% of Down syndrome cases at a 5% false-positive rate, 94% of cases at a 3% false-positive rate, and 71% of cases at a 1% false-positive rate. These detection rates exceed those of any previously reported combination of biochemical markers.

CONCLUSIONS

Hyperglycosylated hCG is a new base marker for Down syndrome screening in the second trimester of pregnancy. The measurement of hyperglycosylated hCG can fundamentally improve the performance of Down syndrome screening protocols.

Synthesis and biological activity of polyethylene glycol-mouse nerve growth factor conjugate

Conjugation of poly(ethylene glycol) derivatives with therapeutic proteins is a promising approach for enhancing protein stability and, therefore, effectiveness. An N-hydroxysuccinimidyl ester of fluorescein-PEG 2000 was used for chemical modification of mouse nerve growth factor (mNGF), a dimeric protein with therapeutic potential for Alzheimer's disease. The mNGF-PEG2000-fluorescein conjugate was characterized by RP-HPLC, spectrofluorometry, and SDS-PAGE and was biologically active, as determined by two independent NGF-specific assays (enhancement of ChAT activity in fetal neurons and neurite outgrowth in PC12 cells). The conjugate was not detectable by a standard NGF ELISA, suggesting a fortuitous reduction in protein recognition by antibodies.

Elevated maternal urine level of beta-core fragment of human chorionic gonadotropin versus serum triple test in the second-trimester detection of down syndrome

OBJECTIVE

This study was undertaken to compare the Down syndrome screening efficiency of elevated maternal urine level of the beta-core fragment of human chorionic gonadotropin with that of the traditional serum triple test.

STUDY DESIGN

Urinary beta-core fragment and serum analyte levels were measured prospectively in women with singleton pregnancies who were undergoing second-trimester genetic amniocentesis. Urinary analyte levels were measured within a week of specimen collection. In some cases only alpha-fetoprotein was measured initially and human chorionic gonadotropin and unconjugated estriol levels were subsequently determined from the stored serum specimens. The Down syndrome screening efficiency of urinary concentration of beta-core fragment plus maternal age was compared with that of the traditional triple test. Receiver operating characteristic curves were generated for each algorithm and the areas under the curves were compared to determine which algorithm was superior.

RESULTS

There were a total of 926 study patients, of whom 21 (2.3%) carried fetuses with Down syndrome. The mean (+/-SD) gestations at amniocentesis were 16.6 +/- 1.5 weeks for the fetuses without Down syndrome and 17.7 +/- 2.3 for the fetuses with Down syndrome. A total of 539 women (4 of whom carried fetuses with Down syndrome) had serum alpha-fetoprotein alone measured initially. Urinary concentration of beta-core fragment had a 61.9% detection rate with a 4.9% false-positive rate for Down syndrome, whereas the values for the triple screen were 57. 1% and 11.2%, respectively. The areas under the receiver-operating characteristic curves were 0.8744 for elevated urinary beta-core fragment level and 0.7504 for the triple screen (P =.1116). When the false-positive rate was fixed at an ideal threshold value (</=5%) the urine test was superior (area under the curve, 0.0212 vs 0.0133, P <.05). Similarly, when we considered only cases in which the complete triple screen was performed prospectively (17 fetuses with Down syndrome and 431 fetuses without Down syndrome), the urine test was significantly better (area under the curve, 0.873 vs 0.624, P =.012).

CONCLUSION

In this first reported direct comparison we consistently observed higher sensitivity values for screening with urinary levels of beta-core fragment than for serum triple screen, suggesting an equivalent or superior Down syndrome screening performance for the urinary analyte. It is important that freezing and prolonged urine storage before testing be avoided. The reduced cost (single- versus triple-analyte testing) and excellent screening performance support large-scale testing and evaluation of maternal urinary beta-core fragment measurement as an alternative to the traditional serum triple test.

The meanings and correlates of spirituality: suggestions from an exploratory survey of experts

There has been an increasing interest in spirituality among health care professionals over the last several decades. Specialists in the areas of trauma, grief, and death and dying have been among those who have shown particular interest in religious and spiritual issues. Recent efforts to distinguish religiosity from spirituality have stimulated inquiries into the changing meanings of these dimensions. Drawing on prior and parallel works, the authors created a questionnaire and asked for responses to it from convenience samples of experts in death studies (n = 22) and spiritual studies (n = 13). Our findings are suggestive of possible lines of convergence and divergence. Both groups considered themselves to be spiritual but not religious, and there was consensus that the meaning of the term spirituality is currently changing. There was also general agreement that spiritual experiences are meaningful learning opportunities and that spiritual individuals tend to be more hopeful and to experience more meaning or purpose in life than their nonspiritual peers. The themes most strongly associated with spirituality in both groups were charity, community or connectedness, compassion, forgiveness, hope, meaning, and morality. Future research should be directed toward clarifying what people mean by "spiritual" and how they experience and express this dimension of their lives.

Cystic hygroma in the fetus and newborn

Cystic hygromas are developmental abnormalities of the lymphoid system that occur at sites of lymphatic-venous connection, most commonly in the posterior neck. They are frequently associated with karyotypic abnormalities, various malformation syndromes, and several teratogenic agents. The disease course of an infant with cystic hygroma is unpredictable. When diagnosed prenatally, the overall prognosis is poor. Cystic hygroma diagnosed after birth is usually associated with a good prognosis. This article reviews the embryologic, genetic, and pathologic correlates of these lymphatic system abnormalities, as well as the clinical course and outcome of the fetus and newborn with a cystic hygroma. Management strategies are reviewed, including newer nonsurgical therapies for the neonate with a cystic hygroma.

Millimeter-scale positioning of a nerve-growth-factor source and biological activity in the brain

Toxicity prevents the systemic administration of many therapeutic proteins, and attempts at protein targeting via the circulatory system (i.e., "magic bullets") have failed in all but a few special cases. Direct administration at the target site is a logical alternative, particularly in the central nervous system, but the limits of direct administration have not been defined clearly. Nerve growth factor (NGF) enhances survival of cholinergic neurons and, therefore, has generated considerable interest for the treatment of Alzheimer's disease. We tested the effectiveness of local delivery by implanting small polymer pellets that slowly released NGF into the central nervous system of adult rats at controlled distances from a target site containing transplanted fetal cholinergic cells. NGF-releasing implants placed within 1-2 mm of the treatment site enhanced the biological function of cellular targets, whereas identical implants placed approximately 3 mm from the target site of treatment produced no beneficial effect. Effective NGF therapy required millimeter-scale positioning of the NGF source, and efficacy correlated with the spatial distribution of NGF concentration in the tissue; this result suggests that NGF must be delivered within several millimeters of the target to be effective in treating Alzheimer's disease. Because the human brain is divided into functional regions that are typically several centimeters in diameter and often irregular in shape, new methods for sculpting larger-scale drug fields are needed. We illustrate a concept, called pharmacotectonics, in which drug-delivery systems are arranged spatially in tissues to shape concentration fields for potent agents.

Urinary screening tests for fetal Down syndrome: II. Hyperglycosylated hCG

Hyperglycosylated hCG is a form of hCG with more complex oligosaccharide side chains. A specific immunoassay was developed to measure hyperglycosylated hCG. Levels were measured in urine samples from 1157 women between 11 to 22 weeks of gestation, undergoing genetic analysis because of advanced maternal age. Values were normalized to urine creatinine concentration and plotted against gestational age, median values were determined and multiples of the control median (MoM) calculated. The median MoM and log standard deviation (log SD) of the 1134 control samples was 1.0 and 0.47, and of the 23 Down syndrome cases was 7.8 and 0.48, respectively. This indicated a 7.8-fold increase in hyperglycosylated hCG levels in Down syndrome cases. In the accompanying article, a stability problem was found with beta-core fragment measurements in frozen urine samples. In anticipation of similar problems, nine urine samples were tested for hyperglycosylated hCG fresh and after storage in the freezer. No clear difference was found in hyperglycosylated hCG values. In addition, no trend was found in hyperglycosylated hCG MoM values or in Down syndrome detection rates in urine samples stored for one, two or three years in the freezer. Samples were split into five equal groups according to creatinine concentration. A trend was observed, hyperglycosylated hCG MoM values decreasing with advancing creatinine concentration (1.77, 1.08, 1.01, 0.73 and 0.60 at 0.25, 0.50, 0.79, 1.11 and 1.73 mg/ml, respectively). An error was noted. This was corrected with a regression equation. After correction, the median MoM and log SD of the control samples was 1.0 and 0.44, and of Down syndrome samples was 7.3 and 0.42, respectively. Correction of this error, while reducing the elevation of Down syndrome cases, tightened the spread of samples. Samples were ranked and centiles determined. 18 of 23 Down syndrome cases (78 per cent) exceeded the 95th centile of the control population. ROC analysis indicated 79 per cent detection at 5 per cent false-positive rate. Urine samples were collected during two periods of gestation, an early period (11th to 14th completed week) and the period when chemical screening is normally performed (15th to 21st week). ROC analysis indicated 80 per cent and 78 per cent detection rates, respectively, at 5 per cent false-positive rate, in the two gestational periods. Hyperglycosylated hCG values were modelled with beta-core fragment values, total oestriol values and maternal age. ROC analysis indicated 97 per cent detection rate at 5 per cent false-positive rate. This detection rate and this level of Down syndrome and control patient discrimination surpasses that of any other serum, urine or ultrasound screening protocol. Hyperglycosylated hCG should be considered as a new screening test for aneuploid pregnancies, with the potential of detecting almost all cases of Down syndrome. Evaluation is needed by other centres in order to bring hyperglycosylated hCG into clinical practice.

Urinary screening tests for fetal Down syndrome: I. Fresh beta-core fragment

Variable results have been reported using urine beta-core fragment as a marker for fetal Down syndrome. Initial studies by Cuckle et al. (1994) and Canick et al. (1995) indicated that beta-core fragment was an outstanding marker, detecting >80 per cent of Down syndrome cases. Since these reports, widely varying results have been published, indicating between 20 per cent and 66 per cent detection of cases at 5 per cent false-positive rate. The wide variation in the reported data has led to a loss of enthusiasm for this marker as a useful test for Down syndrome screening. Here we report the results of a three-year prospective study in which urine samples were collected daily from women undergoing fetal karyotype analysis for advanced maternal age. Samples were tested within one week of collection and then frozen. We also investigated the likely causes of the variability observed in beta-core fragment data. We collected 1157 urine samples over 955 days. Beta-core fragment levels were measured. A regression line was calculated for the weekly medians of the 1134 control samples and multiples of the control median (MoM) were determined. The median MoM for the controls was 1.0 and the logarithmic standard deviation (log SD) was 0.41. The median MoM for the 23 Down syndrome cases was 5.44 and the log SD was 0.45. Over the study period, 65 per cent of Down syndrome cases exceeded the 95th centile of the control group. The median MoM of control samples and the proportion of Down syndrome cases detected by the test was relatively constant during the study period. The unaffected cases were divided into three equal divisions, corresponding to approximately the first, second and third year of sample collection. No trend was found in the median control MoM values in three sample collection periods (r2=0.04). A similar number of cases exceeded the 95th centile of control samples in the three sample collection periods, 63 per cent, 66 per cent and 66 per cent. Consistent results were indicated during the three years of sample testing. Levels of total oestriol were determined in urine samples and MoM statistics derived. The median oestriol level in Down syndrome cases was 0.59 MoM. Only 12 per cent of cases had MoM levels below the fifth centile. Gaussian models were prepared combining biochemical data and maternal age distribution. While beta-core fragment by itself detected 65 per cent of Down syndrome cases, beta-core fragment modelled with maternal age detected 66 per cent, and modelled with age and total oestriol levels detected 82 per cent of cases at 5 per cent false-positive rate. At the completion of the study, we thawed and reassayed 20 random urine samples (10 control and 10 Down syndrome) collected at different times during the study period. While the control samples (74-1700 ng/ml) had slightly increased values when reassayed (mean value 137 per cent of original prospective value), the Down syndrome samples (360-20,500 ng/ml) all had decreased values when reassayed (mean=53 per cent, t-test, controls versus cases, p = 0.0003). The Down syndrome samples were decreased to between 93 per cent and 12 per cent of the original value. A relationship was identified between the magnitude of the original beta-core fragment value and the change in immunoreactivity when reassayed (r2=0.998). The higher the initial beta-core fragment value the greater the loss of immunoreactivity. We considered the possibility that the beta-core fragment molecules aggregate upon storage in the freezer. We repeated the assay of the 20 samples after treatment with a high salt buffer. Down syndrome samples recovered half of the lost beta-core fragment immunoreactivity (mean increase in beta-core fragment levels 56 per cent, t-test, controls versus cases, p=0.004). We infer that aggregation of beta-core fragment upon storage interferes with beta-core fragment measurements. This may be the cause of the poor beta-core fragment screening performance reported using sto

Gestational age standardized nuchal thickness values for estimating mid-trimester Down's syndrome risk

OBJECTIVE

Our aim was to develop gestational age standardized indices of fetal nuchal thickening. In addition, we wanted to develop a method for combining nuchal thickness data with maternal age for calculating individual Down's syndrome risk.

METHODS

Nuchal thickness was measured prospectively in pregnancies undergoing genetic amniocentesis. A regression equation for expected median nuchal thickness based on the biparietal diameter (BPD) was developed. Nuchal thickness values were expressed as multiples of the median (MoM). Additionally, a new parameter, percentage increase in nuchal thickness (PIN) (measured minus expected nuchal thickness) X100/expected nuchal thickness, was used. Receiver operator characteristics curves for Down's syndrome detection based on nuchal thickness values expressed as MoM, PIN, and in mm were compared. Log10 transformation of MoM data resulted in a Gaussian distribution, and the Down's syndrome likelihood ratios were calculated based on the heights of the Gaussian curves. Likelihood ratios were also calculated based on PIN values. The screening efficiency of maternal age alone was compared to age plus MoM, and age plus PIN values by multiplying age-related risk by the likelihood ratio corresponding to the given nuchal thickness MoM or PIN values.

RESULTS

There were 3,574 chromosomally normal and 50 Down's syndrome fetuses in the study. Both PIN and MoM values for nuchal thickness were closely correlated (R = 1.00, P<0.001) and each was poorly correlated with gestational age (R = 0.018, P = 0.28). The Down's syndrome screening efficiency of PIN, MoM, and nuchal thickness values in mm were not significantly different. The addition of nuchal thickness data to maternal age-related risk significantly improved the Down's syndrome screening efficiency: Area under the ROC curve for maternal age risk = 0.58, maternal age + PIN area = 0.79 (P<0.001 compared to maternal age alone) and for maternal age + MoM = 0.77 (P<0.005 compared to maternal age alone).

CONCLUSIONS

The development of gestational age standardized nuchal thickness indices makes it possible to combine ultrasound and maternal age-related risk to derive individual Down's syndrome odds.

Cultures of cells from fetal rat brain: methods to control composition, morphology, and biochemical activity

Fetal tissue transplantation is a promising new approach for the treatment of neurodegenerative diseases, but the optimal conditions for preparing cells for transplantation have not been defined. The growth of a population of septal brain cells, primarily containing cholinergic neurons and glia, was characterized after seeding at densities from 5 x 10(4) to 6 x 10(5) cells/cm2, on polystyrene-, collagen-, laminin-, and fibronectin-coated surfaces, in the presence of serum and/or serum-free medium. Differentiated glial cells were selected by culture on fibronectin or laminin surfaces, in the presence of low amounts of serum (2.5% FBS) and G5, a soluble factor containing EGF and insulin. Differentiated neuronal cells were selected by culture on laminin, in the presence of low amounts of serum (2.5% FBS) and N2, a soluble factor containing supplemental hormones. In each case, a minimum seeding density of 1 x 10(5) cells/cm2 was required. Neuronal growth could be maintained long term (21 days) with high levels of neuronal activity (ChAT activity).

Nuchal thickness, urine beta-core fragment level, and maternal age for down syndrome screening

OBJECTIVE

Our purpose was to report the midtrimester Down syndrome screening efficiency of a 2-analyte algorithm, urine beta-core fragment (a metabolite of human chorionic gonadotropin) and nuchal thickness, along with maternal age in a high-risk population undergoing genetic amniocentesis.

METHOD

Nuchal thickness, humerus length, and maternal urine beta-core fragment levels were measured prospectively before genetic amniocentesis in 1360 singleton pregnancies, 21 (1.5%) of which had fetal Down syndrome. All analyte levels were expressed as multiples of the normal medians based on biparietal diameter. Backward-stepwise logistic regression was used to determine whether the markers were significant independent predictors of fetal Down syndrome. Matrix analysis was used to calculate an adjusted Down syndrome likelihood ratio for each patient based on the significant screening markers. Multiplication by age-related midtrimester risk gave the adjusted Down syndrome risk. The sensitivity and false-positive rates at different Down syndrome screening thresholds were used to generate a receiver-operator characteristics curve. The area under the curve was used to assess the value of this screening test.

RESULTS

On the basis of logistic regression, beta-core fragment level (P 1/60 the sensitivity and false-positive rate for Down syndrome were 85.7% and 4.9%, respectively, when beta-core fragment level, nuchal thickness, and maternal age were used. Correspondence screening values at a risk threshold > 1/150 were 95.2% and 10.8%, respectively. The area under the receiver-operator characteristics curve was 0.9357 (SE = 0. 0137), indicating that the algorithm is excellent for Down syndrome screening.

CONCLUSION

In this study, a combination algorithm consisting of nuchal thickness, urine beta-core fragment level, and maternal age had a high screening efficiency for Down syndrome. This algorithm should be investigated as a new option for women at high risk of having a fetus with Down syndrome.

Intracranial delivery of recombinant nerve growth factor: release kinetics and protein distribution for three delivery systems

PURPOSE

Three different polymeric delivery systems, composed of either poly(ethylene-co-vinyl acetate) (EVAc) or poly(lactide-co-glycolide) (PLGA), were used to administer recombinant human nerve growth factor (rhNGF) intracranially in rats.

METHODS

The delivery systems were characterized with respect to release kinetics, both in the brain and in well-stirred buffer solutions.

RESULTS

During incubation in buffered saline, the delivery systems released rhNGF in distinct patterns: sustained (EVAc), immediate (PLGA1) and delayed (PLGA2). One 10-mg delivery system was implanted in each rat and an ELISA technique was used to determine the amount of rhNGF in 1-mm coronal brain slices produced immediately after removal of the delivery system. High levels of rhNGF (as high as 60,000 ng in a brain slice of approximately 50 microliters) were recovered from the brain tissue at 1, 2, and 4 weeks after implantation. With all three delivery systems, the amount of rhNGF in each brain slice decreased exponentially with distance from the implant site: the distance over which concentration decreased by 10-fold was 2-3 mm for all delivery systems. When rhNGF release was moderate (10 to 200 ng rhNGF/day), the total amount of rhNGF in the brain increased linearly with release rate, suggesting an overall rate of rhNGF elimination of 0.4 hr-1 or a half-life of 1.7 hr. With higher release rates (500 to 50,000 ng rhNGF/day), total amounts of rhNGF in the brain were considerably higher than anticipated based on this rate of elimination.

CONCLUSIONS

Polymeric controlled release can provide high, localized doses of rhNGF in the brain. All of the experimental data were consistent with penetration of rhNGF through the brain tissue with a diffusion coefficient approximately 8 x 10(-7) cm2/s, which is approximately 50% of the diffusion coefficient in water.