Tumor vascular permeability and the EPR effect in macromolecular therapeutics: a review

Most solid tumors possess unique pathophysiological characteristics that are not observed in normal tissues or organs, such as extensive angiogenesis and hence hypervasculature, defective vascular architecture, impaired lymphatic drainage/recovery system, and greatly increased production of a number of permeability mediators. The phenomenon now known as the enhanced permeability and retention (EPR) effect for lipid and macromolecular agents has been observed to be universal in solid tumors. Primarily, enhanced vascular permeability will sustain an adequate supply of nutrients and oxygen for rapid tumor growth. The EPR effect also provides a great opportunity for more selective targeting of lipid- or polymer-conjugated anticancer drugs, such as SMANCS and PK-1, to the tumor. In the present review, the basic characteristics of the EPR effect, particularly the factors involved, are described, as well as its modulation for improving delivery of macromolecular drugs to the tumor. Tumor-specific vascular physiology is also described.

Activation of NK cells and T cells by NKG2D, a receptor for stress-inducible MICA

Stress-inducible MICA, a distant homolog of major histocompatibility complex (MHC) class I, functions as an antigen for gammadelta T cells and is frequently expressed in epithelial tumors. A receptor for MICA was detected on most gammadelta T cells, CD8+ alphabeta T cells, and natural killer (NK) cells and was identified as NKG2D. Effector cells from all these subsets could be stimulated by ligation of NKG2D. Engagement of NKG2D activated cytolytic responses of gammadelta T cells and NK cells against transfectants and epithelial tumor cells expressing MICA. These results define an activating immunoreceptor-MHC ligand interaction that may promote antitumor NK and T cell responses.

A mechanistic study of the antibacterial effect of silver ions on Escherichia coli and Staphylococcus aureus

To investigate the mechanism of inhibition of silver ions on microorganisms, two strains of bacteria, namely Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), were treated with AgNO(3) and studied using combined electron microscopy and X-ray microanalysis. Similar morphological changes occurred in both E. coli and S. aureus cells after Ag(+) treatment. The cytoplasm membrane detached from the cell wall. A remarkable electron-light region appeared in the center of the cells, which contained condensed deoxyribonucleic acid (DNA) molecules. There are many small electron-dense granules either surrounding the cell wall or depositing inside the cells. The existence of elements of silver and sulfur in the electron-dense granules and cytoplasm detected by X-ray microanalysis suggested the antibacterial mechanism of silver: DNA lost its replication ability and the protein became inactivated after Ag(+) treatment. The slighter morphological changes of S. aureus compared with E. coli recommended a defense system of S. aureus against the inhibitory effects of Ag(+) ions.

The integrin alpha v beta 6 binds and activates latent TGF beta 1: a mechanism for regulating pulmonary inflammation and fibrosis

Transforming growth factor beta (TGF beta) family members are secreted in inactive complexes with a latency-associated peptide (LAP), a protein derived from the N-terminal region of the TGF beta gene product. Extracellular activation of these complexes is a critical but incompletely understood step in regulation of TGF beta function in vivo. We show that TGF beta 1 LAP is a ligand for the integrin alpha v beta 6 and that alpha v beta 6-expressing cells induce spatially restricted activation of TGF beta 1. This finding explains why mice lacking this integrin develop exaggerated inflammation and, as we show, are protected from pulmonary fibrosis. These data identify a novel mechanism for locally regulating TGF beta 1 function in vivo by regulating expression of the alpha v beta 6 integrin.

Present-day crustal deformation in China constrained by global positioning system measurements

Global Positioning System (GPS) measurements in China indicate that crustal shortening accommodates most of India's penetration into Eurasia. Deformation within the Tibetan Plateau and its margins, the Himalaya, the Altyn Tagh, and the Qilian Shan, absorbs more than 90% of the relative motion between the Indian and Eurasian plates. Internal shortening of the Tibetan plateau itself accounts for more than one-third of the total convergence. However, the Tibetan plateau south of the Kunlun and Ganzi-Mani faults is moving eastward relative to both India and Eurasia. This movement is accommodated through rotation of material around the eastern Syntaxis. The North China and South China blocks, east of the Tibetan Plateau, move coherently east-southeastward at rates of 2 to 8 millimeters per year and 6 to 11 millimeters per year, respectively, with respect to the stable Eurasia.

The pyroptosome: a supramolecular assembly of ASC dimers mediating inflammatory cell death via caspase-1 activation

Pyroptosis is a caspase-1-dependent inflammatory form of cell death. The adapter protein ASC binds directly to caspase-1 and is critical for caspase-1 activation in response to a broad range of stimuli. To elucidate the mechanism of activation of caspase-1 by ASC and its exact role in macrophage pyroptosis, we performed time-lapse confocal bioimaging analysis on human THP-1 macrophages stably expressing an ASC-GFP fusion protein. We show that stimulation of these cells with several proinflammatory stimuli trigger the formation of a large supramolecular assembly of ASC, termed here pyroptosome. Only one distinct pyroptosome in each stimulated cell is formed, which rapidly recruits and activates caspase-1 resulting in pyroptosis and the release of the intracellular proinflammatory cytokines. The pyroptosome is largely composed of oligomerized ASC dimers. Dimerization of ASC is driven by subphysiological concentrations of potassium as in vitro incubation of purified recombinant ASC in the presence of subphysiological concentrations of potassium induces the assembly of a functional pyroptosome. Furthermore, stimulation of potassium efflux in THP-1 cells with potassium-depleting agents induces formation of the pyroptosome, while increasing potassium concentrations in the culture medium or pharmacological inhibition of this efflux inhibits its assembly. Our results establish that macrophage pyroptosis is mediated by a unique pyroptosome, distinct from the inflammasome.

Hyperglycemia-induced mitochondrial superoxide overproduction activates the hexosamine pathway and induces plasminogen activator inhibitor-1 expression by increasing Sp1 glycosylation

The hexosamine pathway has been implicated in the pathogenesis of diabetic complications. We determined first that hyperglycemia induced a decrease in glyceraldehyde-3-phosphate dehydrogenase activity in bovine aortic endothelial cells via increased production of mitochondrial superoxide and a concomitant 2.4-fold increase in hexosamine pathway activity. Both decreased glyceraldehyde-3-phosphate dehydrogenase activity and increased hexosamine pathway activity were prevented completely by an inhibitor of electron transport complex II (thenoyltrifluoroacetone), an uncoupler of oxidative phosphorylation (carbonyl cyanide m-chlorophenylhydrazone), a superoxide dismutase mimetic [manganese (III) tetrakis(4-benzoic acid) porphyrin], overexpression of either uncoupling protein 1 or manganese superoxide dismutase, and azaserine, an inhibitor of the rate-limiting enzyme in the hexosamine pathway (glutamine:fructose-6-phosphate amidotransferase). Immunoprecipitation of Sp1 followed by Western blotting with antibodies to O-linked GlcNAc, phosphoserine, and phosphothreonine showed that hyperglycemia increased GlcNAc by 1.7-fold, decreased phosphoserine by 80%, and decreased phosphothreonine by 70%. The same inhibitors prevented all these changes. Hyperglycemia increased expression from a transforming growth factor-beta(1) promoter luciferase reporter by 2-fold and increased expression from a (-740 to +44) plasminogen activator inhibitor-1 promoter luciferase reporter gene by nearly 3-fold. Inhibition of mitochondrial superoxide production or the glucosamine pathway prevented all these changes. Hyperglycemia increased expression from an 85-bp truncated plasminogen activator inhibitor-1 (PAI-1) promoter luciferase reporter containing two Sp1 sites in a similar fashion (3.8-fold). In contrast, hyperglycemia had no effect when the two Sp1 sites were mutated. Thus, hyperglycemia-induced mitochondrial superoxide overproduction increases hexosamine synthesis and O-glycosylation of Sp1, which activates expression of genes that contribute to the pathogenesis of diabetic complications.

An activating immunoreceptor complex formed by NKG2D and DAP10

Many immune receptors are composed of separate ligand-binding and signal-transducing subunits. In natural killer (NK) and T cells, DAP10 was identified as a cell surface adaptor protein in an activating receptor complex with NKG2D, a receptor for the stress-inducible and tumor-associated major histocompatibility complex molecule MICA. Within the DAP10 cytoplasmic domain, an Src homology 2 (SH2) domain-binding site was capable of recruiting the p85 subunit of the phosphatidylinositol 3-kinase (PI 3-kinase), providing for NKG2D-dependent signal transduction. Thus, NKG2D-DAP10 receptor complexes may activate NK and T cell responses against MICA-bearing tumors.

Inhibition of the EGF-activated MAP kinase signaling pathway by adenosine 3',5'-monophosphate

Mitogen-activated protein (MAP) kinases p42mapk and p44mapk are activated in cells stimulated with epidermal growth factor (EGF) and other agents. A principal pathway for MAP kinase (MAPK) activation by EGF consists of sequential activations of the guanine nucleotide exchange factor Sos, the guanosine triphosphate binding protein Ras, and the protein kinases Raf-1, MAPK kinase (MKK), and MAPK. Because adenosine 3',5'-monophosphate (cAMP) does not activate MAPK and has some opposing physiologic effects, the effect of increasing intracellular concentrations of cAMP with forskolin and 3-isobutyl-1-methylxanthine on the EGF-stimulated MAPK pathway was studied. Increased concentrations of cAMP blocked activation of Raf-1, MKK, and MAPK in Rat1hER fibroblasts, accompanied by a threefold increase in Raf-1 phosphorylation on serine 43 in the regulatory domain. Phosphorylation of Raf-1 in vitro and in vivo reduces the apparent affinity with which it binds to Ras and may contribute to the blockade by cAMP.

From acute ER stress to physiological roles of the Unfolded Protein Response

When protein folding in the endoplasmic reticulum (ER) is disrupted by alterations in homeostasis in the ER lumen, eucaryotic cells activate a series of signal transduction cascades that are collectively termed the unfolded protein response (UPR). Here we summarize our current understanding of how the UPR functions upon acute and severe stress. We discuss the mechanism of UPR receptor activation, UPR signal transduction to translational and transcriptional responses, UPR termination, and UPR signals that activate upon irreversible damage. Further, we review recent studies that have revealed that UPR provides a wide spectrum of physiological roles. Each individual UPR subpathway provides a unique and specialized role in diverse developmental and metabolic processes. This is especially observed for professional secretory cells, such as plasma cells, pancreatic beta cells, hepatocytes, and osteoblasts, where high-level secretory protein synthesis requires a highly evolved mechanism to properly fold, process, and secrete proteins. There is a growing body of data that suggest that different subpathways of the UPR are required throughout the entire life of eucaryotic organisms, from regulation of differentiation to induction of apoptosis.

Functional gamma-secretase inhibitors reduce beta-amyloid peptide levels in brain

Converging lines of evidence implicate the beta-amyloid peptide (Ass) as causative in Alzheimer's disease. We describe a novel class of compounds that reduce A beta production by functionally inhibiting gamma-secretase, the activity responsible for the carboxy-terminal cleavage required for A beta production. These molecules are active in both 293 HEK cells and neuronal cultures, and exert their effect upon A beta production without affecting protein secretion, most notably in the secreted forms of the amyloid precursor protein (APP). Oral administration of one of these compounds, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester, to mice transgenic for human APP(V717F) reduces brain levels of Ass in a dose-dependent manner within 3 h. These studies represent the first demonstration of a reduction of brain A beta in vivo. Development of such novel functional gamma-secretase inhibitors will enable a clinical examination of the A beta hypothesis that Ass peptide drives the neuropathology observed in Alzheimer's disease.

Immunoreceptor DAP12 bearing a tyrosine-based activation motif is involved in activating NK cells

Natural killer (NK) cells express cell-surface receptors of the immunoglobulin and C-type lectin superfamilies that recognize major histocompatibility complex (MHC) class I peptides and inhibit NK-cell-mediated cytotoxicity. These inhibitory receptors possess ITIM sequences (for immunoreceptor tyrosine-based inhibitory motifs) in their cytoplasmic domains that recruit SH2-domain-containing protein tyrosine phosphatases, resulting in inactivation of NK cells. Certain isoforms of these NK-cell receptors lack ITIM sequences and it has been proposed that these 'non-inhibitory' receptors may activate, rather than inhibit, NK cells. Here we show that DAP12, a disulphide-bonded homodimer containing an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic domain, non-covalently associates with membrane glycoproteins of the killer-cell inhibitory receptor (KIR) family without an ITIM in their cytoplasmic domain. Crosslinking of KIR-DAP12 complexes results in cellular activation, as demonstrated by tyrosine phosphorylation of cellular proteins and upregulation of early-activation antigens. Phosphorylated DAP12 peptides bind ZAP-70 and Syk protein tyrosine kinases, suggesting that the activation pathway is similar to that of the T- and B-cell antigen receptors.

SREBP-1, a basic-helix-loop-helix-leucine zipper protein that controls transcription of the low density lipoprotein receptor gene

Sterol regulatory element 1 (SRE-1), a decamer (5'-ATC-ACCCCAC-3') flanking the low density lipoprotein (LDL) receptor gene, activates transcription in sterol-depleted cells and is silenced by sterols. We report the cDNA cloning of human SREBP-1, a protein that binds SRE-1, activates transcription, and thereby mediates the final regulatory step in LDL metabolism. SREBP-1 contains a basic-helix-loop-helix-leucine zipper (bHLH-ZIP) motif, but it differs from other bHLH-ZIP proteins in its larger size (1147 amino acids) and target sequence. Instead of an inverted repeat (CANNTG), the target for all known bHLH-ZIP proteins, SRE-1 contains a direct repeat of CAC. Overexpression of SREBP-1 activates transcription of reporter genes containing SRE-1 in the absence (15-fold) and presence (90-fold) of sterols, abolishing sterol regulation. We suggest that SREBP-1 is regulated by an unknown factor that is overwhelmed when SREBP-1 is overexpressed. Understanding the regulation of SREBP-1 may be crucial for understanding the control of plasma cholesterol in humans.

A comparative evaluation of thiobarbituric acid methods for the determination of malondialdehyde in biological materials

A comparative evaluation was made of the conventional spectrophotometric procedure and three published high performance liquid chromatographic (HPLC) procedures for the determination of malondialdehyde (MDA) as the thiobarbituric acid (TBA) derivative when applied to liver, fish meal, serum, and urine. Except for urine, spectrophotometric analysis overestimated MDA content. Purification of the TBA-MDA complex obtained from liver and fish meal on reverse phase cartridges was found to entail a loss of complex bound to residual peptides in the trichloracetic acid (TCA) extract. Mincing as opposed to homogenizing liver samples led to a doubling of values for MDA content. Hexanal was a major TBA reactant, in addition to MDA, in all the samples. Acid hydrolysis and heat were necessary for the release of MDA bound to the amino groups of proteins and other amino compounds. Methods for free MDA have limited application to biological materials except short term in vitro preparations such as peroxidizing microsomes, in which free MDA accumulates. On the basis of these and other observations, a modified HPLC procedure for the determination of MDA as the TBA-MDA complex is proposed.

Cancer-associated fibroblast exosomes regulate survival and proliferation of pancreatic cancer cells

Cancer associated fibroblasts (CAFs) comprise the majority of the tumor bulk of pancreatic adenocarcinomas (PDACs). Current efforts to eradicate these tumors focus predominantly on targeting the proliferation of rapidly growing cancer epithelial cells. We know that this is largely ineffective with resistance arising in most tumors following exposure to chemotherapy. Despite the long-standing recognition of the prominence of CAFs in PDAC, the effect of chemotherapy on CAFs and how they may contribute to drug resistance in neighboring cancer cells is not well characterized. Here we show that CAFs exposed to chemotherapy play an active role in regulating the survival and proliferation of cancer cells. We found that CAFs are intrinsically resistant to gemcitabine, the chemotherapeutic standard of care for PDAC. Further, CAFs exposed to gemcitabine significantly increase the release of extracellular vesicles called exosomes. These exosomes increased chemoresistance-inducing factor, Snail, in recipient epithelial cells and promote proliferation and drug resistance. Finally, treatment of gemcitabine-exposed CAFs with an inhibitor of exosome release, GW4869, significantly reduces survival in co-cultured epithelial cells, signifying an important role of CAF exosomes in chemotherapeutic drug resistance. Collectively, these findings show the potential for exosome inhibitors as treatment options alongside chemotherapy for overcoming PDAC chemoresistance.

Amygdala activity at encoding correlated with long-term, free recall of emotional information

Positron emission tomography of cerebral glucose metabolism in adult human subjects was used to investigate amygdaloid complex (AC) activity associated with the storage of long-term memory for emotionally arousing events. Subjects viewed two videos (one in each of two separate positron emission tomography sessions, separated by 3-7 days) consisting either of 12 emotionally arousing film clips ("E" film session) or of 12 relatively emotionally neutral film clips ("N" film session), and rated their emotional reaction to each film clip immediately after viewing it. Three weeks after the second session, memory for the videos was assessed in a free recall test. As expected, the subjects' average emotional reaction to the E films was higher than that for the N films. In addition, the subjects recalled significantly more E films than N films. Glucose metabolic rate of the right AC while viewing the E films was highly correlated with the number of E films recalled. AC activity was not significantly correlated with the number of N films recalled. The findings support the view derived from both animal and human investigations that the AC is selectively involved with the formation of enhanced long-term memory associated with emotionally arousing events.

A novel polymorphism of FcgammaRIIIa (CD16) alters receptor function and predisposes to autoimmune disease

A novel polymorphism in the extracellular domain 2 (EC2) of FcgammaRIIIA affects ligand binding by natural killer (NK) cells and monocytes from genotyped homozygous normal donors independently of receptor expression. The nonconservative T to G substitution at nucleotide 559 predicts a change of phenylalanine (F) to valine (V) at amino acid position 176. Compared with F/F homozygotes, FcgammaRIIIa expressed on NK cells and monocytes in V/V homozygotes bound more IgG1 and IgG3 despite identical levels of receptor expression. In response to a standard aggregated human IgG stimulus, FcgammaRIIIa engagement on NK cells from V/V (high-binding) homozygotes led to a larger rise in [Ca2+]i, a greater level of NK cell activation, and a more rapid induction of activation-induced cell death (by apoptosis). Investigation of an independently phenotyped normal cohort revealed that all donors with a low binding phenotype are F/F homozygotes, while all phenotypic high binding donors have at least one V allele. Initial analysis of 200 patients with SLE indicates a strong association of the low binding phenotype with disease, especially in patients with nephritis who have an underrepresentation of the homozygous high binding phenotype. Thus, the FcgammaRIIIa polymorphism at residue 176 appears to impact directly on human biology, an effect which may extend beyond autoimmune disease characterized by immune complexes to host defense mechanisms.

Retinoic acid early inducible genes define a ligand family for the activating NKG2D receptor in mice

Here we describe a family of GPI-anchored cell surface proteins that function as ligands for the mouse activating NKG2D receptor. These molecules are encoded by the retinoic acid early inducible (RAE-1) and H60 minor histocompatibility antigen genes on mouse chromosome 10 and show weak homology with MHC class I. Expression of the NKG2D ligands is low or absent on normal, adult tissues; however, they are constitutively expressed on some tumors and upregulated by retinoic acid. Ectopic expression of RAE-1 and H60 confers target susceptibility to NK cell attack. These studies identify a family of ligands for the activating NKG2D receptor on NK and T cells, which may play an important role in innate and adaptive immunity.

SU6656, a selective src family kinase inhibitor, used to probe growth factor signaling

The use of small-molecule inhibitors to study molecular components of cellular signal transduction pathways provides a means of analysis complementary to currently used techniques, such as antisense, dominant-negative (interfering) mutants and constitutively activated mutants. We have identified and characterized a small-molecule inhibitor, SU6656, which exhibits selectivity for Src and other members of the Src family. A related inhibitor, SU6657, inhibits many kinases, including Src and the platelet-derived growth factor (PDGF) receptor. The use of SU6656 confirmed our previous findings that Src family kinases are required for both Myc induction and DNA synthesis in response to PDGF stimulation of NIH 3T3 fibroblasts. By comparing PDGF-stimulated tyrosine phosphorylation events in untreated and SU6656-treated cells, we found that some substrates (for example, c-Cbl, and protein kinase C delta) were Src family substrates whereas others (for example, phospholipase C-gamma) were not. One protein, the adaptor Shc, was a substrate for both Src family kinases (on tyrosines 239 and 240) and a distinct tyrosine kinase (on tyrosine 317, which is perhaps phosphorylated by the PDGF receptor itself). Microinjection experiments demonstrated that a Shc molecule carrying mutations of tyrosines 239 and 240, in conjunction with an SH2 domain mutation, interfered with PDGF-stimulated DNA synthesis. Deletion of the phosphotyrosine-binding domain also inhibited synthesis. These inhibitions were overcome by heterologous expression of Myc, supporting the hypothesis that Shc functions in the Src pathway. SU6656 should prove a useful additional tool for further dissecting the role of Src kinases in this and other signal transduction pathways.

SREBP-2, a second basic-helix-loop-helix-leucine zipper protein that stimulates transcription by binding to a sterol regulatory element

We report the cDNA cloning of SREBP-2, the second member of a family of basic-helix-loop-helix-leucine zipper (bHLH-Zip) transcription factors that recognize sterol regulatory element 1 (SRE-1). SRE-1, a conditional enhancer in the promoters for the low density lipoprotein receptor and 3-hydroxy-3-methylglutaryl-coenzyme A synthase genes, increases transcription in the absence of sterols and is inactivated when sterols accumulate. Human SREBP-2 contains 1141 amino acids and is 47% identical to human SREBP-1a, the first recognized member of this family. The resemblance includes an acidic NH2 terminus, a highly conserved bHLH-Zip motif (71% identical), and an unusually long extension of 740 amino acids on the COOH-terminal side of the bHLH-Zip region. SREBP-2 possesses one feature lacking in SREBP-1a--namely, a glutamine-rich region (27% glutamine over 121 residues). In vitro SREBP-2 bound SRE-1 with the same specificity as SREBP-1a. In vivo it mimicked SREBP-1a in activating transcription of reporter genes containing SRE-1. As with SREBP-1a, activation by SREBP-2 occurred in the absence and presence of sterols, abolishing regulation. Cotransfection of low amounts of pSREBP-1a and pSREBP-2 into human embryonic kidney 293 cells stimulated transcription of promoters containing SRE-1 in an additive fashion. At high levels transcription reached a maximum, and the effects were no longer additive. The reason for the existence of two SREBPs and the mechanism by which they are regulated by sterols remain to be determined.

Association of DAP12 with activating CD94/NKG2C NK cell receptors

While the inhibitory NK cell receptors for MHC class I express immunoreceptor tyrosine-based inhibitory motifs that recruit intracellular tyrosine phosphatases and prevent NK cell effector function, the activating NK cell receptors lack intrinsic sequences required for cellular stimulation. CD94/NKG2C, an activating NK cell receptor of the C-type lectin superfamily that binds to HLA-E, noncovalently associates with DAP12, a membrane receptor containing an immunoreceptor tyrosine-based activating motif. Efficient expression of CD94/NKG2C on the cell surface requires the presence of DAP12, and charged residues in the transmembrane domains of DAP12 and NKG2C are necessary for this interaction. These results provide a molecular basis for the assembly of NK cell receptors for MHC class I involved in cellular activation and inhibition.

Global histone acetylation and deacetylation in yeast

Histone acetyltransferases and deacetylases can be targeted to promoters to activate or repress genes. For example, the histone acetyltransferase GCN5 is part of a yeast multiprotein complex that is recruited by the DNA-binding activator protein GCN4 (refs 1-3). The histone deacetylase RPD3 complex is recruited to DNA by the repressor UME6 (refs 4, 5); similar mechanisms exist in other eukaryotes. However, deletion of RPD3 also increases expression of the PHO5 gene that is repressed by nucleosomes, and regulated by GCN5 (ref. 10) but not by UME6. We have determined whether acetylation and deacetylation are promoter specific at PHO5, by using antibodies against acetylated lysine residues and chromatin immunoprecipitation to examine the acetylation state of a 4.25-kilobase region surrounding the PHO5 gene. Here we show that this region is acetylated extensively by ESA1 and GCN5 and deacetylated by HDA1 and RPD3, and that widespread histone modification affects three separate chromosomal regions examined, which total 22kb. Our data indicate that targeted modification occurs in a background of global acetylation and deacetylation that not only reduces basal transcription, but also allows a rapid return to the initial state of acetylation when targeting is removed.

Rapid 3D printing of anatomically accurate and mechanically heterogeneous aortic valve hydrogel scaffolds

The aortic valve exhibits complex three-dimensional (3D) anatomy and heterogeneity essential for the long-term efficient biomechanical function. These are, however, challenging to mimic in de novo engineered living tissue valve strategies. We present a novel simultaneous 3D printing/photocrosslinking technique for rapidly engineering complex, heterogeneous aortic valve scaffolds. Native anatomic and axisymmetric aortic valve geometries (root wall and tri-leaflets) with 12-22 mm inner diameters (ID) were 3D printed with poly-ethylene glycol-diacrylate (PEG-DA) hydrogels (700 or 8000 MW) supplemented with alginate. 3D printing geometric accuracy was quantified and compared using Micro-CT. Porcine aortic valve interstitial cells (PAVIC) seeded scaffolds were cultured for up to 21 days. Results showed that blended PEG-DA scaffolds could achieve over tenfold range in elastic modulus (5.3±0.9 to 74.6±1.5 kPa). 3D printing times for valve conduits with mechanically contrasting hydrogels were optimized to 14 to 45 min, increasing linearly with conduit diameter. Larger printed valves had greater shape fidelity (93.3±2.6, 85.1±2.0 and 73.3±5.2% for 22, 17 and 12 mm ID porcine valves; 89.1±4.0, 84.1±5.6 and 66.6±5.2% for simplified valves). PAVIC seeded scaffolds maintained near 100% viability over 21 days. These results demonstrate that 3D hydrogel printing with controlled photocrosslinking can rapidly fabricate anatomical heterogeneous valve conduits that support cell engraftment.