Testicular hyaluronidase induces tubular structures of endothelial cells grown in three-dimensional collagen gel through a CD44-mediated mechanism

CD44 in Ovarian Cancer Progression and Therapy Resistance-A Critical Role for STAT3

Despite significant progress in cancer therapy over the last decades, ovarian cancer remains the most lethal gynecologic malignancy worldwide with the five-year overall survival rate less than 30% due to frequent disease recurrence and chemoresistance. CD44 is a non-kinase transmembrane receptor that has been linked to cancer metastatic progression, cancer stem cell maintenance, and chemoresistance development via multiple mechanisms across many cancers, including ovarian, and represents a promising therapeutic target for ovarian cancer treatment. Moreover, CD44-mediated signaling interacts with other well-known pro-tumorigenic pathways and oncogenes during cancer development, such as signal transducer and activator of transcription 3 (STAT3). Given that both CD44 and STAT3 are strongly implicated in the metastatic progression and chemoresistance of ovarian tumors, this review summarizes currently available evidence about functional crosstalk between CD44 and STAT3 in human malignancies with an emphasis on ovarian cancer. In addition to the role of tumor cell-intrinsic CD44 and STAT3 interaction in driving cancer progression and metastasis, we discuss how CD44 and STAT3 support the pro-tumorigenic tumor microenvironment and promote tumor angiogenesis, immunosuppression, and cancer metabolic reprogramming in favor of cancer progression. Finally, we review the current state of therapeutic CD44 targeting and propose superior treatment possibilities for ovarian cancer.

Migration of endothelial cells and mesenchymal stem cells into hyaluronic acid hydrogels with different moduli under induction of pro-inflammatory macrophages

The design of hyaluronic acid (HA)-based and stimuli-responsive hydrogels to elicit highly controlled and tunable cell response and behaviors is a major field of interest in tissue engineering and regenerative medicine. The pH-responsive hydrogel can respond to pH variation during wound healing, which may in turn regulate the tissue regeneration process. In this study, a double-network hydrogel cross-linked with vinyl double bonds and Schiff base was prepared, whose properties were further adjusted by incubation in pH 7.4 and pH 5 buffers. The endothelial cells (ECs) migrated much deeper into the softer HA hydrogel pre-treated with pH 5 buffer than the stiffer hydrogel. By contrast, the mesenchymal stem cells (MSCs) migrated easily into the stiffer hydrogel. The ECs highly expressed RhoA and non-muscle myosin (NM) II genes in the softer hydrogel, which may facilitate amoeboid migration. Meanwhile, the MSCs were stiffer than the ECs, and highly expressed Rac1, RhoA, vinculin, NM II, hyaluronidase (HYAL) 2 and CD44 genes in the stiffer hydrogel, which facilitate mesenchymal migration. These results provide important clues for revealing the different migration strategies of the ECs and MSCs in HA hydrogels with different stiffness, and suggest that the mechanical properties and the network structure of hydrogels play an important role in regulating the three-dimensional migration process of these cells.

Intrastromal Injection of Hyaluronidase Alters the Structural and Biomechanical Properties of the Corneal Stroma

Purpose

Glycosaminoglycans (GAGs) are important components of the corneal stroma, and their spatiotemporal arrangement regulates the organization of collagen fibrils and maintains corneal transparency. This study was undertaken to determine the consequences of hyaluronidase (HAse) injected into the corneal stroma on stromal stiffness and ultrastructure.

Methods

Equal volumes of HAse or balanced salt solution (vehicle) were injected intrastromally into the corneas of New Zealand white rabbits. Ophthalmic examination and multimodal imaging techniques, including Fourier-domain optical coherence tomography and in vivo confocal microscopy (IVCM), were performed at multiple time points to evaluate the impact of HAse treatment in vivo. Atomic force microscopy and transmission electron microscopy (TEM) were used to measure corneal stiffness and collagen's interfibrillar spacing, respectively.

Results

Central corneal thickness progressively decreased after HAse injection, reaching its lowest value at day 7, and then returned to normal by day 42. The HAse did not impact the corneal endothelium but transiently altered keratocyte morphology at days 1 and 7, as measured by IVCM. HAse-injected corneas became stiffer by day 1 postinjection, were stiffest at day 7, and returned to preinjection values by day 90. Changes in stromal stiffness correlated with decreased interfibrillar spacing as measured by TEM.

Conclusions

Degradation of GAGs by HAse decreases the corneal thickness and increases stromal stiffness through increased packing of the collagen fibrils in a time-dependent manner.

Translational Relevance

Intrastromal HAse injection appears relatively safe in the normal cornea, but its impact on corneal biomechanics and structure under pathologic conditions requires further study.

Involvement of hyaluronan and CD44 in cancer and viral infections

Hyaluronan and its major receptor CD44 are ubiquitously distributed. They have important structural as well as signaling roles, regulating tissue homeostasis, and their expression levels are tightly regulated. In addition to signaling initiated by the interaction of the intracellular domain of CD44 with cytoplasmic signaling molecules, CD44 has important roles as a co-receptor for different types of receptors of growth factors and cytokines. Dysregulation of hyaluronan-CD44 interactions is seen in diseases, such as inflammation and cancer. In the present communication, we discuss the mechanism of hyaluronan-induced signaling via CD44, as well as the involvement of hyaluronan-engaged CD44 in malignancies and in viral infections.

High levels of serum hyaluronan is an early predictor of dengue warning signs and perturbs vascular integrity

BACKGROUND

A main pathological feature of severe dengue virus infection is endothelial hyper-permeability. The dengue virus nonstructural protein 1 (NS1) has been implicated in the vascular leakage that characterizes severe dengue virus infection, however, the molecular mechanisms involved are not known.

METHODS

A cohort of 250 dengue patients has been followed from the onset of symptoms to the recovery phase. Serum hyaluronan levels and several other clinical parameters were recorded. The effect of NS1 treatment of cultured fibroblasts and endothelial cells on the expressions of hyaluronan synthetic and catabolic enzymes and the hyaluronan receptor CD44, were determined, as have the effects on the formation of hyaluronan-rich matrices and endothelial permeability.

FINDINGS

Elevated serum hyaluronan levels (≥70 ng/ml) during early infection was found to be an independent predictor for occurrence of warning signs, and thus severe dengue fever. High circulating levels of the viral protein NS1, indicative of disease severity, correlated with high concentrations of serum hyaluronan. NS1 exposure decreased the expression of CD44 in differentiating endothelial cells impairing the integrity of vessel-like structures, and promoted the synthesis of hyaluronan in dermal fibroblasts and endothelial cells in synergy with dengue-induced pro-inflammatory mediators. Deposited hyaluronan-rich matrices around cells cultured in vitro recruited CD44-expressing macrophage-like cells, suggesting a mechanism for enhancement of inflammation. In cultured endothelial cells, perturbed hyaluronan-CD44 interactions enhanced endothelial permeability through modulation of VE-cadherin and cytoskeleton re-organization, and exacerbated the NS1-induced disruption of endothelial integrity.

INTERPRETATION

Pharmacological targeting of hyaluronan biosynthesis and/or its CD44-mediated signaling may limit the life-threatening vascular leakiness during moderate-to-severe dengue virus infection. FUND: This work was supported in part by grants from the Swedish Cancer Society (2018/337; 2016/445), the Swedish Research Council (2015-02757), the Ludwig Institute for Cancer Research, Uppsala University, the Ministry of Science and Technology, Taiwan (106-2314-B-037-088- and 106-2915-I-037-501-), Kaohsiung Medical University Hospital (KMUH103-3 T05) and Academy of Finland. The funders played no role in the design, interpretation or writing of the manuscript.

CD44-dependent inflammation, fibrogenesis, and collagenolysis regulates extracellular matrix remodeling and tensile strength during cutaneous wound healing

Cutaneous wound healing consists of three main phases: inflammation, re-epithelialization, and tissue remodeling. During normal wound healing, these processes are tightly regulated to allow restoration of skin function and biomechanics. In many instances, healing leads to an excess accumulation of fibrillar collagen (the principal protein found in the extracellular matrix - ECM), and the formation of scar tissue, which has compromised biomechanics, tested using ramp to failure tests, compared to normal skin (Corr and Hart, 2013 [1]). Alterations in collagen accumulation and architecture have been attributed to the reduced tensile strength found in scar tissue (Brenda et al., 1999; Eleswarapu et al., 2011). Defining mechanisms that govern cellular functionality and ECM remodeling are vital to understanding normal versus pathological healing and developing approaches to prevent scarring. CD44 is a cell surface adhesion receptor expressed on nearly all cell types present in dermis. Although CD44 has been implicated in an array of inflammatory and fibrotic processes such as leukocyte recruitment, T-cell extravasation, and hyaluronic acid (the principal glycosaminoglycan found in the ECM) metabolism, the role of CD44 in cutaneous wound healing and scarring remains unknown. We demonstrate that in an excisional biopsy punch wound healing model, CD44-null mice have increased inflammatory and reduced fibrogenic responses during early phases of wound healing. At wound closure, CD44-null mice exhibit reduced collagen degradation leading to increased accumulation of fibrillar collagen, which persists after wound closure leading to reduced tensile strength resulting in a more severe scarring phenotype compared to WT mice. These data indicate that CD44 plays a previously unknown role in fibrillar collagen accumulation and wound healing during the injury response.

Knock-down of CD44 regulates endothelial cell differentiation via NFκB-mediated chemokine production

A striking feature of microvascular endothelial cells is their capacity to fuse and differentiate into tubular structures when grown in three-dimensional (3D) extracellular matrices, in collagen or Matrigel, mimicking the in vivo blood vessel formation. In this study we demonstrate that human telomerase-immortalised foreskin microvascular endothelial (TIME) cells express high levels of the hyaluronan receptor CD44 and the hyaluronidase HYAL2. Knock-down of CD44 or HYAL2 resulted in an inability of TIME cells to form a tubular network, suggesting a key regulatory role of hyaluronan in controlling TIME cell tubulogenesis in 3D matrices. Knock-down of CD44 resulted in an upregulation of mRNA expression of the chemokines CXCL9 and CXCL12, as well as their receptors CXCR3 and CXCR4. This was accompanied by a defect maturation of the tubular structure network and increased phosphorylation of the inhibitor of NFκB kinase (IKK) complex and thus translocation of NFκB into the nucleus and activation of chemokine targed genes. Furthermore, the interaction between CD44 and hyaluronan determines the adhesion of breast cancer cells. In summary, our observations support the notion that the interaction between CD44 and hyaluronan regulates microvascular endothelial cell tubulogenesis by affecting the expression of cytokines and their receptors, as well as breast cancer dissemination.

The roles of hyaluronan/RHAMM/CD44 and their respective interactions along the insidious pathways of fibrosarcoma progression

Fibrosarcomas are rare malignant mesenchymal tumors originating from fibroblasts. Importantly, fibrosarcoma cells were shown to have a high content and turnover of extracellular matrix (ECM) components including hyaluronan (HA), proteoglycans, collagens, fibronectin, and laminin. ECMs are complicated structures that surround and support cells within tissues. During cancer progression, significant changes can be observed in the structural and mechanical properties of the ECM components. Importantly, hyaluronan deposition is usually higher in malignant tumors as compared to benign tissues, predicting tumor progression in some tumor types. Furthermore, activated stromal cells are able to produce tissue structure rich in hyaluronan in order to promote tumor growth. Key biological roles of HA result from its interactions with its specific CD44 and RHAMM (receptor for HA-mediated motility) cell-surface receptors. HA-receptor downstream signaling pathways regulate in turn cellular processes implicated in tumorigenesis. Growth factors, including PDGF-BB, TGFβ2, and FGF-2, enhanced hyaluronan deposition to ECM and modulated HA-receptor expression in fibrosarcoma cells. Indeed, FGF-2 through upregulation of specific HAS isoforms and hyaluronan synthesis regulated secretion and net hyaluronan deposition to the fibrosarcoma pericellular matrix modulating these cells' migration capability. In this paper we discuss the involvement of hyaluronan/RHAMM/CD44 mediated signaling in the insidious pathways of fibrosarcoma progression.

Fibronectin-hyaluronic acid composite hydrogels for three-dimensional endothelial cell culture

Biomaterials that actively promote both wound healing and angiogenesis are of critical importance for many biomedical applications, including tissue engineering. In particular, hyaluronic acid (HA) is an important player that has multiple roles throughout the angiogenic process in the body. Previously, our laboratory has developed photocrosslinkable HA-based scaffolds that promote angiogenesis when implanted in vivo. This paper reports the incorporation of a photocrosslinkable fibronectin (FN) conjugate into three-dimensional (3-D) HA hydrogel networks to enhance endothelial cell adhesion and angiogenesis. The results demonstrate significantly better retention of FN that was photocrosslinked within HA hydrogels compared to FN that was physically adsorbed within HA hydrogels. Increased viability of endothelial cells cultured in 3-D HA hydrogels with photoimmobilized FN, compared to adsorbed FN, was also observed. Endothelial cells were cultured within hydrogels for up to 6 days, a period over which cell proliferation, migration and an angiogenic phenotype were influenced by varying the concentration of incorporated FN. The results demonstrate the potential of these composite hydrogels as biomaterial scaffolds capable of promoting wound healing and angiogenesis.

Bacteriophage hyaluronidase effectively inhibits growth, migration and invasion by disrupting hyaluronan-mediated Erk1/2 activation and RhoA expression in human breast carcinoma cells

Aberrant hyaluronan production has been implicated in many types of tumor. In this context, hyaluronidase has been explored as a viable therapeutic approach to reduce tumoral hyaluronan. However, elevated levels of hyaluronan in tumors are often associated with high expression levels of cellular hyaluronidases, which consequently produce various sizes of saturated hyaluronan fragments with divergent pro-tumoral activities. The current study shows that different hyaluronan metabolisms of mammalian and microbial hyaluronidases could elicit distinct alterations in cancer cell behavior. Unlike saturated hyaluronan metabolites, unsaturated hyaluronan oligosaccharides produced by bacteriophage hyaluronidase, HylP, had no biological effect on growth of breast carcinoma cells. More importantly, HylP's metabolic process of hyaluronan into non-detrimental oligosaccharides significantly decreased breast cancer cell proliferation, migration and invasion by disrupting Erk1/2 activation and RhoA expression. Our results suggest that it may be possible to exploit HylP's unique enzymatic activity in suppressing hyaluronan-mediated tumor growth and progression.

Involvement of endothelial CD44 during in vivo angiogenesis

CD44, a cell-surface receptor for hyaluronan, has been implicated in endothelial cell functions, but its role in the formation of blood vessels in vivo has not been established. In CD44-null mice, vascularization of Matrigel implants and tumor and wound angiogenesis were inhibited. Leukocyte accumulation during tumor growth and wound healing in wild-type and CD44-null mice were comparable, and reconstitution of CD44-null mice with wild-type bone marrow did not restore the wild-type phenotype, suggesting that impairments in angiogenesis in CD44-deficient mice are due to the loss of endothelial CD44. Although the cell proliferation, survival, and wound-induced migration of CD44-null endothelial cells were intact, these cells were impaired in their in vitro ability to form tubes. Nascent vessels in Matrigel implants from CD44-null mice demonstrated irregular luminal surfaces characterized by retracted cells and thinned endothelia. Further, an anti-CD44 antibody that disrupted in vitro tube formation induced hemorrhage around Matrigel implants, suggesting that antagonism of endothelial CD44 undermined the integrity of the endothelium of nascent vessels. These data establish a role for CD44 during in vivo angiogenesis and suggest that CD44 may contribute to the organization and/or stability of developing endothelial tubular networks.

The over-expression of HAS2, Hyal-2 and CD44 is implicated in the invasiveness of breast cancer

Within tumors there appears to be an intricate balance between hyaluronan (HA) synthesis and degradation where the invading edges display increased HA metabolism. The metabolism of HA has not been characterized in breast cancer cell lines; therefore, this study quantitatively identifies and characterizes the enzymes responsible for the synthesis and degradation of HA while correlating gene expression to cancer cell invasiveness and HA receptor status. In ten well-established breast cancer cell lines, the expression of the genes for each hyaluronan synthase (HAS) and hyaluronidase (Hyal) isoform was quantitated using real-time and reverse transcriptase polymerase chain reaction (PCR). The synthesis and degradation rates of hyaluronan were determined by ELISA, while quantitation of HA receptors, CD44 and RHAMM was performed by comparative Western blotting. The molecular weight of HA synthesized by each HAS isoform and the degradation products of each hyaluronidase were characterized by size exclusion chromatography. It was demonstrated that highly invasive cell lines preferentially expressed the HAS2 and Hyal-2 isoforms, while less invasive cells expressed HAS3 and Hyal-3. There was a correlation between elevated levels of HA synthesis, CD44 expression and cancer cell migration thereby highlighting the pivotal role that HA metabolism plays in the aggressive breast cancer phenotype.

Male castration increases neuronal nitric oxide synthase activity in the rat mesenteric artery through protein kinase C activation

The objective of the present study was to assess the effect of endogenous male sex hormones on the activity of protein kinase C (PKC), as well as the regulatory effect of this kinase on the neuronal nitric oxide (NO) release induced by electrical field stimulation (EFS; 200 mA; 0.3 ms; 1-16 Hz). For this purpose, superior mesenteric arteries from control and orchidectomized male Sprague-Dawley rats were used. PKC activity was greater in arteries from orchidectomized than control rats. Basal and EFS-induced NO release was similar in arteries from both groups despite the lower nNOS expression in arteries from orchidectomized rats. Phorbol 12,13-dibutyrate (PDBu), a PKC activator, EFS-induced NO release was higher in arteries from control compared to orchidectomized rats. Calphostin C, a non-selective PKC inhibitor, or Gö6976, a PKC inhibitor partially selective for conventional isoforms,abolished the EFS-induced NO release in arteries from control animals, while it was decreased in arteries from orchidectomized animals. The PKCzeta pseudosubstrate inhibitor decreased EFS-induced NO release equally in both groups. The NO synthase (NOS) inhibitor Nomega-nitro-L-arginine-methyl ester (L-NAME) enhanced the EFS-elicited contractions in arteries from both groups. Calphostin C increased the contractions elicited by EFS in arteries from control and orchidectomized rats. This increase was further enhanced by calphostin C plus L-NAME only in orchidectomized rats. PDBu reduced EFS-induced contraction in arteries from controls but did not affect it in orchidectomized rats. The further addition of L-NAME increased the responses in both types of arteries. These results show that PKC activity is enhanced in mesenteric arteries from orchidectomized rats, which may be the responsible for the greater nNOS activity in these arteries. Conventional and atypical PKCzeta isoforms positively regulate nNOS activity in arteries from both control and orchidectomized rats, but the contribution of conventional PKC isoforms to enhanced nNOS activity seems to be greater in arteries from orchidectomized rats.

Engagement of CD44 modulates cyclooxygenase induction, VEGF generation, and proliferation in human vascular endothelial cells

CD44 is a receptor for hyaluronic acid and is found on the surface of hematopoetic cells and in mesenchymal tissue. It is also expressed on endothelial cells (EC). Cyclooxygenase (COX) is the rate-limiting enzyme in the production of prostaglandins in EC. Here we show that engagement of CD44 with signaling monoclonal antibodies (mAbs) or its natural ligand hyaluronic acid induces COX-2 and prostacyclin (PGI2) formation in human EC. This induction was blocked by mAbs that have been shown to inhibit CD44-mediated intracellular signaling. COX-1 induction was not observed after CD44 ligation. CD44-stimulated COX-2 activation/PGI2 production was accompanied by the production of the potent endothelial mitogen, vascular endothelial growth factor (VEGF) and was inhibited by a neutralizing VEGF antibody. Moreover, this COX-2 induction was also associated with an increase in EC proliferation that was inhibited by the blocking anti-CD44 mAbs and a COX-2-specific inhibitor. This is the first study to show that engagement of CD44 with mAbs or its natural ligand induces COX-2, generates VEGF, and thus leads to an increase in EC proliferation. Results from this study may have important and widespread implications for the development of novel therapeutic agents for modulating blood vessel growth during ischemic heart disease, during inflammation, or around solid tumors.

Identification of an active site on the laminin alpha5 chain globular domain that binds to CD44 and inhibits malignancy

The laminin alpha5 chain is a component of laminin-10 (alpha5beta1gamma1) and -11 (alpha5beta2gamma1). In this study, we have screened 113 overlapping synthetic peptides from the laminin alpha5 globular domain (G-domain) for cell attachment activity with B16-F10 cells using peptide-coated dishes. Eleven attachment-active peptides were identified. In vivo experimental B16-F10 pulmonary metastasis and primary tumor growth assays found that 4 of the 11 peptides inhibited tumor metastasis and growth and increased apoptosis. These four peptides also blocked tumor cell migration, invasion, and angiogenesis. Two of the peptides were highly homologous and showed significant similarity to sequences in collagens. We sought to identify the B16-F10 cell surface receptors for each of the four active peptides using peptide affinity chromatography. Only one peptide recognized a cell surface protein. Peptide A5G27 (RLVSYNGIIFFLK, residues 2892-2904) bound a diffuse M(r) approximately 120,000-180,000 band that eluted with 2 m NaCl. Glycosidase digestion of the 2 m eluate yielded protein bands of M(r) 90,000 and 60,000 that reacted in Western blot analysis with antibodies to CD44. Immunoprecipitation of the A5G27-bound membrane proteins with various cell surface proteoglycan antibodies confirmed CD44 as the surface receptor for A5G27. Finally, attachment assays to A5G27 in the presence of soluble glycosaminoglycans (GAGs) identified the GAGs of CD44 as the binding sites for A5G27. Our results suggest that A5G27 binds to the CD44 receptor of B16-F10 melanoma cells via the GAGs on CD44 and, thus, inhibits tumor cell migration, invasion, and angiogenesis in a dominant-negative manner.

Importance of hyaluronan biosynthesis and degradation in cell differentiation and tumor formation

Hyaluronan is an important connective tissue glycosaminoglycan. Elevated hyaluronan biosynthesis is a common feature during tissue remodeling under both physiological and pathological conditions. Through its interactions with hyaladherins, hyaluronan affects several cellular functions such as cell migration and differentiation. The activities of hyaluronan-synthesizing and -degrading enzymes have been shown to be regulated in response to growth factors. During tumor progression hyaluronan stimulates tumor cell growth and invasiveness. Thus, elucidation of the molecular mechanisms which regulate the activities of hyaluronan-synthesizing and -degrading enzymes during tumor progression is highly desired.

Relationship between lymph and tissue hyaluronan in skin and skeletal muscle

The size of hyaluronan was compared between tissue and lymph using a combination of agarose gel electrophoresis and radiometric assay. Prenodal lymph was collected from heel skin and the gastrocnemius muscle in anesthetized rabbits. The major fraction of hyaluronan in both tissues had a molecular weight >4 million. Lymph contained primarily low-molecular-weight hyaluronan (<0.79 x 10(6)), which was absent from tissue. Volume loading produced a preferential increase in the flux of low-molecular-weight hyaluronan, indicating that tissue contains a small quantity of mobile, low-molecular-weight hyaluronan. The maximum daily removal of hyaluronan by lymph was <1% of the tissue content. The amount of lysosomal hyaluronidase activity in tissue was more than enough to account for a rapid turnover of hyaluronan. The data support the conclusion that lymph drainage is not significant in the normal catabolism of hyaluronan and may represent a small amount that becomes detached from the pericellular and extracellular matrixes.

Expression of hyaluronan synthase 2 or hyaluronidase 1 differentially affect the growth rate of transplantable colon carcinoma cell tumors

Advanced colorectal cancers are often associated with elevated amounts of hyaluronan. To investigate the importance of hyaluronan in colon carcinoma tumor progression, we have expressed by stable transfection hyaluronan synthase 2 (Has2) and hyaluronidase 1 (Hyal1) in the rat colon carcinoma cell line, PROb. We found that hyaluronan overproduction led to a higher growth rate of tumor cells in vitro, and to a faster development of transplantable tumors in syngeneic rats, compared to the mock-transfectants. Has2 transfected PROb cells gave rise to tumors that were significantly less vascularized, but had a significantly larger viable tumor fraction compared to tumors generated from mock-transfectants. In contrast, Hyal1 overexpression suppressed the growth rate of tumor cells both in vitro and in vivo. Moreover, tumors derived from Hyal1-transfected cells had a significantly larger necrotic area than tumors derived from mock- and Has2-transfectants. Our study demonstrates that Has2 overproduction promotes tumorigenicity, whereas Hyal1 overexpression suppresses tumorigenicity in an experimental model for colon carcinoma.

Improvement of rat liver graft function after storage in University of Wisconsin solution containing testicular hyaluronidase

Hyaluronan accumulates at sites of inflammation, which affects the organization of matrix and thereby the proliferation, migration, and adherence of cells. In this study we investigated possible beneficial effects of the hyaluronan-degrading enzyme hyaluronidase on rat liver graft viability. Orthotopic rat liver transplantation was performed using a cuff technique in Wistar AL Bacharach Glaxo (WAG) rats grafted with WAG livers, which had been stored in the University of Wisconsin (UW) solution or in UW solution enriched with testicular hyaluronidase. Liver tissue architecture, as well as tissue and serum hyaluronan levels, were determined using immunohistochemistry and biochemical assays. Addition of testicular hyaluronidase (0.4 mg/mL) to livers preserved for 24 hours in cold UW solution followed by brief exposure to Ringer's lactate both prolonged the function of the grafted livers and improved their viability (4 of 10 grafts survived, compared with 0 of 10 in the control group). Hyaluronidase treatment did not damage the liver tissue architecture, and a reduced edema was observed in the survivors. Furthermore, 10 minutes after restoration of circulation, higher serum hyaluronan levels were observed in nonsuccessful compared with successful transplantations, whereas no differences in the levels of other serum viability markers were detected. We conclude that addition of testicular hyaluronidase to storage UW solution limits liver cell damage and considerably improves graft function. Furthermore, our data suggest that serum hyaluronan level is a better marker than other serum markers for early evaluation of postoperative graft function.

Ischemia-reperfusion does not cause significant hyaluronan depolymerization in skeletal muscle

The size of hyaluronan in lymph and gastrocnemius muscle was measured to test the hypothesis that reperfusion of ischemic skeletal muscle leads to hyaluronan depolymerization. Prenodal lymph was collected from the gastrocnemius muscle in anesthetized rabbits. Hyaluronan size was measured using a combination of agarose gel electrophoresis and a radiometric assay. In control legs, muscle contained primarily high-molecular-weight hyaluronan (greater then 4 x 10(6)), while lymph contained primarily low-molecular-weight hyaluronan (less than 0.79 x 10(6)) which was absent from tissue. Following 3 h of ischemia and 8 h of reperfusion, the lymph flux for high-molecular-weight hyaluronan was 25 times the value from the control leg. Neither the size nor the content of hyaluronan in tissue decreased. Muscle albumin content from the reperfused leg was 2.3 times the value from the control leg, while lymph albumin flux was 4 times the control value. Measurements following 24 h of reperfusion confirmed the absence of changes in the size or content of hyaluronan in tissue although an increased albumin content and wet weight-to-dry weight ratio indicated sustained edema. The daily removal of hyaluronan by lymph was calculated to be 2-3% of the tissue content. Since the lymph drainage of hyaluronan represented only a very small fraction of tissue hyaluronan, the amount of depolymerization was too small to produce significant changes in the tissue.