A tension offloading patch mitigates dermal fibrosis induced by pro-fibrotic skin injections

Skin fibrosis is a clinical problem with devastating impacts but limited treatment options. In the setting of diabetes, insulin administration often causes local dermal fibrosis, leading to a range of clinical sequelae including impeded insulin absorption. Mechanical forces are important drivers of fibrosis and, clinically, physical tension offloading at the skin level using an elastomeric patch significantly reduces wound scarring. However, it is not known whether tension offloading could similarly prevent skin fibrosis in the setting of pro-fibrotic injections. Here, we develop a porcine model using repeated local injections of bleomycin to recapitulate key features of insulin-induced skin fibrosis. Using histologic, tissue ultrastructural, and biomechanical analyses, we show that application of a tension-offloading patch both prevents and rescues existing skin fibrosis from bleomycin injections. By applying single-cell transcriptomic analysis, we find that the fibrotic response to bleomycin involves shifts in myeloid cell dynamics from favoring putatively pro-regenerative to pro-fibrotic myeloid subtypes; in a mechanomodulatory in vitro platform, we show that these shifts are mechanically driven and reversed by exogenous IL4. Finally, using a human foreskin xenograft model, we show that IL4 treatment mitigates bleomycin-induced dermal fibrosis. Overall, this study highlights that skin tension offloading, using an FDA cleared, commercially available patch, could have significant potential clinical benefit for the millions of patients dependent on insulin.

Purification and functional characterization of novel human skeletal stem cell lineages

Human skeletal stem cells (hSSCs) hold tremendous therapeutic potential for developing new clinical strategies to effectively combat congenital and age-related musculoskeletal disorders. Unfortunately, refined methodologies for the proper isolation of bona fide hSSCs and the development of functional assays that accurately recapitulate their physiology within the skeleton have been lacking. Bone marrow-derived mesenchymal stromal cells (BMSCs), commonly used to describe the source of precursors for osteoblasts, chondrocytes, adipocytes and stroma, have held great promise as the basis of various approaches for cell therapy. However, the reproducibility and clinical efficacy of these attempts have been obscured by the heterogeneous nature of BMSCs due to their isolation by plastic adherence techniques. To address these limitations, our group has refined the purity of individual progenitor populations that are encompassed by BMSCs by identifying defined populations of bona fide hSSCs and their downstream progenitors that strictly give rise to skeletally restricted cell lineages. Here, we describe an advanced flow cytometric approach that utilizes an extensive panel of eight cell surface markers to define hSSCs; bone, cartilage and stromal progenitors; and more differentiated unipotent subtypes, including an osteogenic subset and three chondroprogenitors. We provide detailed instructions for the FACS-based isolation of hSSCs from various tissue sources, in vitro and in vivo skeletogenic functional assays, human xenograft mouse models and single-cell RNA sequencing analysis. This application of hSSC isolation can be performed by any researcher with basic skills in biology and flow cytometry within 1-2 days. The downstream functional assays can be performed within a range of 1-2 months.

OUP accepted manuscript

The tendon enthesis plays a critical role in facilitating movement and reducing stress within joints. Partial enthesis injuries heal in a mechanically inferior manner and never achieve healthy tissue function. The cells responsible for tendon-to-bone healing remain incompletely characterized and their origin is unknown. Here, we evaluated the putative role of mouse skeletal stem cells (mSSCs) in the enthesis after partial-injury. We found that mSSCs were present at elevated levels within the enthesis following injury and that these cells downregulated TGFβ signaling pathway elements at both the RNA and protein levels. Exogenous application of TGFβ post-injury led to a reduced mSSC response and impaired healing, whereas treatment with a TGFβ inhibitor (SB43154) resulted in a more robust mSSC response. Collectively, these data suggest that mSSCs may augment tendon-to-bone healing by dampening the effects of TGFβ signaling within the mSSC niche.

Detection of Stem Cell Transplant Rejection with Ferumoxytol MR Imaging: Correlation of MR Imaging Findings with Those at Intravital Microscopy

Purpose To determine whether endogenous labeling of macrophages with clinically applicable nanoparticles enables noninvasive detection of innate immune responses to stem cell transplants with magnetic resonance (MR) imaging. Materials and Methods Work with human stem cells was approved by the institutional review board and the stem cell research oversight committee, and animal experiments were approved by the administrative panel on laboratory animal care. Nine immunocompetent Sprague-Dawley rats received intravenous injection of ferumoxytol, and 18 Jax C57BL/6-Tg (Csf1r-EGFP-NGFR/FKBP1A/TNFRSF6) 2Bck/J mice received rhodamine-conjugated ferumoxytol. Then, 48 hours later, immune-matched or mismatched stem cells were implanted into osteochondral defects of the knee joints of experimental rats and calvarial defects of Jax mice. All animals underwent serial MR imaging and intravital microscopy (IVM) up to 4 weeks after surgery. Macrophages of Jax C57BL/6-Tg (Csf1r-EGFP-NGFR/FKBP1A/TNFRSF6) 2Bck/J mice express enhanced green fluorescent protein (GFP), which enables in vivo correlation of ferumoxytol enhancement at MR imaging with macrophage quantities at IVM. All quantitative data were compared between experimental groups by using a mixed linear model and t tests. Results Immune-mismatched stem cell implants demonstrated stronger ferumoxytol enhancement than did matched stem cell implants. At 4 weeks, T2 values of mismatched implants were significantly lower than those of matched implants in osteochondral defects of female rats (mean, 10.72 msec for human stem cells and 11.55 msec for male rat stem cells vs 15.45 msec for sex-matched rat stem cells; P = .02 and P = .04, respectively) and calvarial defects of recipient mice (mean, 21.7 msec vs 27.1 msec, respectively; P = .0444). This corresponded to increased recruitment of enhanced GFP- and rhodamine-ferumoxytol-positive macrophages into stem cell transplants, as visualized with IVM and histopathologic examination. Conclusion Endogenous labeling of macrophages with ferumoxytol enables noninvasive detection of innate immune responses to stem cell transplants with MR imaging. ^© RSNA, 2017 Online supplemental material is available for this article.

Abstract 58: Modeling Pathogenesis in Familial Hypertrophic Cardiomyopathy Using Patient-Specific Induced Pluripotent Stem Cells

Background: Hypertrophic cardiomyopathy (HCM) is a prevalent familial cardiac disorder linked to development of heart failure, arrhythmia, and sudden cardiac death. Molecular genetic studies have demonstrated HCM is caused by mutations in genes encoding for the cardiac sarcomere. However, the pathways by which sarcomeric mutations result in myocyte hypertrophy and contractile abnormalities are not well understood.

Methods: We aimed to elucidate the molecular mechanisms underlying the development of HCM through the generation of induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from dermal fibroblasts of a 10 member family, five of whom carry a hereditary HCM missense mutation (Arg663His) in the MYH7 gene.

Results: As compared to control iPSC-CMs derived from healthy family members, HCM iPSC-CMs exhibited enlarged cell size, increased atrial natriuretic factor (ANF) expression, nuclear translocation of nuclear factor of activated T-cells (NFAT), and aggravated contractile dysfunction in response to stimulation by β-adrenergic agonists. Interestingly, both video analysis of beating cells and whole cell patch clamping revealed arrhythmia in a significant portion of diseased iPSC-CMs at the single cell level. Ca 2+ imaging demonstrated elevated cytoplasmic Ca 2+ content and irregular transients in HCM iPSC-CMs prior to the onset of cellular hypertrophy, suggesting the HCM phenotype is triggered by dysfunction in Ca 2+ cycling. Treatment of irregular Ca 2+ homeostasis by the Ca 2+ channel blocker verapamil prevented development of cellular hypertrophy and arrhythmia.

Conclusions: We hypothesize the cellular abnormalities observed in HCM iPSC-CMs are caused by deficiencies in Ca 2+ regulation. We anticipate our findings will elucidate the mechanisms underlying HCM development and identify novel targets for treatment of the disease.

Calcium-based nanoparticles accelerate skin wound healing

Introduction

Nanoparticles (NPs) are small entities that consist of a hydroxyapatite core, which can bind ions, proteins, and other organic molecules from the surrounding environment. These small conglomerations can influence environmental calcium levels and have the potential to modulate calcium homeostasis in vivo. Nanoparticles have been associated with various calcium-mediated disease processes, such as atherosclerosis and kidney stone formation. We hypothesized that nanoparticles could have an effect on other calcium-regulated processes, such as wound healing. In the present study, we synthesized pH-sensitive calcium-based nanoparticles and investigated their ability to enhance cutaneous wound repair.

Methods

Different populations of nanoparticles were synthesized on collagen-coated plates under various growth conditions. Bilateral dorsal cutaneous wounds were made on 8-week-old female Balb/c mice. Nanoparticles were then either administered intravenously or applied topically to the wound bed. The rate of wound closure was quantified. Intravenously injected nanoparticles were tracked using a FLAG detection system. The effect of nanoparticles on fibroblast contraction and proliferation was assessed.

Results

A population of pH-sensitive calcium-based nanoparticles was identified. When intravenously administered, these nanoparticles acutely increased the rate of wound healing. Intravenously administered nanoparticles were localized to the wound site, as evidenced by FLAG staining. Nanoparticles increased fibroblast calcium uptake in vitro and caused contracture of a fibroblast populated collagen lattice in a dose-dependent manner. Nanoparticles also increased the rate of fibroblast proliferation.

Conclusion

Intravenously administered, calcium-based nanoparticles can acutely decrease open wound size via contracture. We hypothesize that their contraction effect is mediated by the release of ionized calcium into the wound bed, which occurs when the pH-sensitive nanoparticles disintegrate in the acidic wound microenvironment. This is the first study to demonstrate that calcium-based nanoparticles can have a therapeutic benefit, which has important implications for the treatment of wounds.

Optimization of flexor tendon tissue engineering with a cyclic strain bioreactor

PURPOSE

Mechanical manipulation of cultured tendon cells can enhance cell proliferation and matrix production. This study aims to determine the bioreactor strain patterns (amplitude, frequency, and on/off ratio) that favor cellular proliferation, promote collagen production, and maintain morphology in candidate cell lines cultured for flexor tendon tissue engineering, including multipotent stromal cells.

METHODS

We studied epitenon tenocytes (Es), sheath fibroblasts (Ss), bone marrow-derived mesenchymal stem cells (BMSCs), and adipoderived stem cells (ASCs). We examined the effects of 3 patterns of cyclic uniaxial strain on cell proliferation, collagen I production, and cell morphology.

RESULTS

Adipoderived stem cells (33% adhesion) and Ss (29%) adhered more strongly to bioreactor membranes than did Es (15%) and BMSCs (7%), p=.04. Continuous cyclic strain (CCS, 8%, 1 Hz) inhibited cell proliferation (p=.01) and increased per-cell collagen production (p=.04) in all cell types. Intermittent cyclic strain (4%, 0.1 Hz, 1 hour on/5 hours off) increased proliferation in ASCs (p=.06) and Ss (p=.04). Intermittent cyclic strain (4%, 0.1 Hz, 1 hour on/2 hours off) increased total collagen production by 25% in ASCs (p=.004) and 20% in Ss (p=.05). Cyclic strain resulted in cell alignment perpendicular to the strain axis, cytoskeletal alignment, and nuclear elongation. These morphological characteristics are similar to those of tenocytes.

CONCLUSIONS

These results demonstrate that intermittent cyclic strain can increase cell proliferation, promote collagen I production, and maintain tenocyte morphology in vitro. Use of a cell bioreactor might accelerate the in vitro stage of tendon tissue engineering.

Connective Tissue Growth Factor–Specific Monoclonal Antibody Therapy Inhibits Pancreatic Tumor Growth and Metastasis

Pancreatic cancer is highly aggressive and refractory to most existing therapies. Past studies have shown that connective tissue growth factor (CTGF) expression is elevated in human pancreatic adenocarcinomas and some pancreatic cancer cell lines. To address whether and how CTGF influences tumor growth, we generated pancreatic tumor cell lines that overexpress different levels of human CTGF. The effect of CTGF overexpression on cell proliferation was measured in vitro in monolayer culture, suspension culture, or soft agar, and in vivo in tumor xenografts. Although there was no effect of CTGF expression on proliferation in two-dimensional cultures, anchorage-independent growth (AIG) was enhanced. The capacity of CTGF to enhance AIG in vitro was linked to enhanced pancreatic tumor growth in vivo when these cells were implanted s.c. in nude mice. Administration of a neutralizing CTGF-specific monoclonal antibody, FG-3019, had no effect on monolayer cell proliferation, but blocked AIG in soft agar. Consistent with this observation, anti-CTGF treatment of mice bearing established CTGF-expressing tumors abrogated CTGF-dependent tumor growth and inhibited lymph node metastases without any toxicity observed in normal tissue. Together, these studies implicate CTGF as a new target in pancreatic cancer and suggest that inhibition of CTGF with a human monoclonal antibody may control primary and metastatic tumor growth.

Reversed latissimus dorsi muscle flap for repair of recurrent congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Neonates with large congenital diaphragmatic hernias (CDH) require prosthetic patch closure of the defect because of the paucity of native diaphragmatic tissue. As the child grows, patch separation can occur necessitating reoperation. Use of vascularized autologous tissue may decrease the incidence of reherniation as tissue incorporation and growth may be improved. The authors report our early experience using a local muscle advancement flap with microneural anastomosis for those children in whom reherniation develops after prosthetic patch placement.

METHODS

Seven patients with CDH (6 left and 1 right) whose synthetic diaphragmatic patch separated from the chest wall resulting in a clinically significant recurrent hernia were followed up with prospectively. After dissecting the ipsilateral latissimus dorsi off the chest wall and dividing the thoracodorsal neurovascular bundle (based on its lumbar blood supply), the synthetic patch was removed via an eighth intercostal incision. The muscle flap was placed into the hemithorax through the bed of the tenth rib and sutured in place over a Vicryl mesh scaffold. The thoracodorsal nerve was anastomosed to the phrenic nerve. Functional analysis of the flap was performed in 4 patients.

RESULTS

Age at placement of the muscle graft ranged from 2 months to 48 months (median, 24 months). There has been no evidence of reherniation after placement of the muscle graft. Long-term outcome and functional analysis of the flap was available in 4 patients (mean, 19 months). Two infants had fluoroscopic and sonographic evidence of nonparadoxical neodiaphragmatic motion. In one of these, electromyographic evidence of function was documented with a phrenic nerve conduction velocity of 22 meters per second. The third infant showed no evidence of neodiaphragmatic motion, and the fourth infant had paradoxical motion.

CONCLUSIONS

This is the first direct documentation of phrenic nerve function in an infant with CDH. An innervated reversed latissimus dorsi (RLD) flap reconstruction for recurrent CDH provides an alternative to prosthetic patch repair. This technique offers the advantages of autologous vascularized tissue with potential phrenic nerve innervation and physiologic neodiaphragmatic motion.

Craniosynostosis in transgenic mice overexpressing Nell-1

Previously, we reported NELL-1 as a novel molecule overexpressed during premature cranial suture closure in patients with craniosynostosis (CS), one of the most common congenital craniofacial deformities. Here we describe the creation and analysis of transgenic mice overexpressing Nell-1. Nell-1 transgenic animals exhibited CS-like phenotypes that ranged from simple to compound synostoses. Histologically, the osteogenic fronts of abnormally closing/closed sutures in these animals revealed calvarial overgrowth and overlap along with increased osteoblast differentiation and reduced cell proliferation. Furthermore, anomalies were restricted to calvarial bone, despite generalized, non-tissue-specific overexpression of Nell-1. In vitro, Nell-1 overexpression accelerated calvarial osteoblast differentiation and mineralization under normal culture conditions. Moreover, Nell-1 overexpression in osteoblasts was sufficient to promote alkaline phosphatase expression and micronodule formation. Conversely, downregulation of Nell-1 inhibited osteoblast differentiation in vitro. In summary, Nell-1 overexpression induced calvarial overgrowth resulting in premature suture closure in a rodent model. Nell-1, therefore, has a novel role in CS development, perhaps as part of a complex chain of events resulting in premature suture closure. On a cellular level, Nell-1 expression may modulate and be both sufficient and required for osteoblast differentiation.

Retinoid signaling directs secondary lineage selection in pancreatic organogenesis

BACKGROUND/PURPOSE

Retinoid signaling plays an important role in many differentiation pathways. Retinoid signaling has been implicated in the induction of differentiation by pancreatic ductal cancer cell lines and in patients with pancreatic cancer. The authors wished to better understand the role of retinoid signaling in pancreatic development.

METHODS

Embryonic pancreas was harvested from mice at serial gestational ages and immunohistochemical analysis was performed for retinoic acid receptors (RAR-alpha, RAR-beta, RAR-gamma), and retinoid X receptors (RXR-alpha, RXR-beta, and RXR-gamma). Also, early embryonic pancreases were cultured for 7 days with exogenous 9-cis retinoic acid (9cRA) or all-trans retinoic acid (atRA) and analyzed histologically and immunohistochemically.

RESULTS

Retinoid receptors were expressed in a lineage-specific distribution, with stronger expression for many in the exocrine compartment. The receptors were not often expressed until late gestation. Exogenous 9cRA induced predominantly ducts instead of acini, plus more mature endocrine (islet) architecture. Exogenous atRA induced predominantly acini instead of ducts, with no apparent endocrine effect.

CONCLUSIONS

Retinoids may have an important role in pancreatic differentiation, with a particular effect on secondary lineage selection between ductal and acinar phenotype. Because the control of ductal versus acinar differentiation has been implicated strongly in the pathogenesis of pancreatic ductal carcinoma, these results may lay the groundwork for studies in the mechanism of induced differentiation of pancreatic ductal cancer by retinoids.

In vitro characteristics of neonatal hemangioma endothelial cells: similarities and differences between normal neonatal and fetal endothelial cells

BACKGROUND

Increased angiogenesis and eventual involution are major characteristics of neonatal hemangiomas. The mechanism to explain this transition is not completely understood.

METHODS

To determine the nature of these changes, endothelial cells were isolated from eight hemangiomas and the growth characteristics and morphology of these cells were compared to cells isolated from normal fetal and neonatal skin. Three cells lines were further characterized by analyzing protein expression with immunohistochemistry and FACS analysis.

RESULTS

Hemangioma endothelial cells converted to a spindle-shaped morphology similar to that of fetal endothelial cells whereas neonatal endothelial cells maintained their characteristic epithelioid morphology. While neonatal, hemangioma and fetal endothelial cells continued to express platelet-endothelial cell adhesion molecule-1 (PECAM-1) and von Willebrand factor (vWf), hemangioma and fetal cells expressed both proteins at a lower level and in a distribution distinct from normal neonatal endothelial cells. Neonatal endothelial cells continued to express epithelial specific Type IV collagen, while hemangioma and fetal endothelial cells produced interstitial Type I collagen.

CONCLUSIONS

Both cell morphology and protein expression of neonatal hemangioma endothelial cells were more characteristic of embryonic microvascular endothelial cells than that of postembryonic cells demonstrating a similarity in these two cell types and suggesting a dysfunction in the normal growth and maturation of endothelial cells in this tumor.

The in utero repair of Tessier number 7 lateral facial clefts created by amniotic band-like compression

The purpose of this study was to determine the effectiveness of intrauterine reconstruction of lateral facial clefts caused by surgically simulated amniotic band compression. The authors hypothesized that intrauterine lysis of these bands could: 1) prevent the progression of cleft formation; 2) normalize facial development; and 3) allow for the scarless repair of these lateral atypical facial clefts. In a prospective randomized trial, eight 65-day gestational fetal lambs (term, 140 days) were exposed via a maternal hysterotomy. A Tessier 7 facial cleft was made by applying a 2.0 nylon suture as a constriction band to the growing face. The sutures were attached to the zygomatic arch and looped circumferentially into the oral commissure. Two weeks after surgery, four of eight animals were re-exposed. All four animals developed phenotypic changes consistent with Tessier 7 lateral facial clefts. These animals were treated in utero by 1) excising the synthetic constricting band, and 2) opening the epithelialized edges of the lateral facial clefts and performing a primary repair. At birth, the bands on the four untreated animals were cut. The lambs developed to 3 months of age, at which time they were evaluated anthropomorphically for changes in soft tissue measurements, and histologically using hematoxylin and eosin and Mason trichrome stain for the degree of scar at the repair site. Tessier 7 lateral facial clefts were produced in all the untreated animals. Each developed macrostomia with an average 2.3-cm lateral displacement of the oral commissure and partial maxillary clefting induced by the pressure of the restriction band. No evidence of tissue necrosis, maceration, or ulceration was noted. In contrast, animals treated in utero were phenotypically normal. There was no evidence of macrostomia and all anthropomorphic measurements were symmetrical. No bony clefts were seen on gross examination. Histologically, there was no evidence of scar formation at the site of the cleft repair. These findings suggest that like the standard cleft lip, atypical lateral facial clefts can be repaired successfully in utero without scarring. Furthermore, lysis of a restriction band in utero can prevent the progression of this facial deformity, leading to normal development of the face.

Wound healing is accelerated by agonists of adenosine A2 (G alpha s-linked) receptors

The complete healing of wounds is the final step in a highly regulated response to injury. Although many of the molecular mediators and cellular events of healing are known, their manipulation for the enhancement and acceleration of wound closure has not proven practical as yet. We and others have established that adenosine is a potent regulator of the inflammatory response, which is a component of wound healing. We now report that ligation of the G alpha s-linked adenosine receptors on the cells of an artificial wound dramatically alters the kinetics of wound closure. Excisional wound closure in normal, healthy mice was significantly accelerated by topical application of the specific A2A receptor agonist CGS-21680 (50% closure by day 2 in A2 receptor antagonists. In rats rendered diabetic (streptozotocin-induced diabetes mellitus) wound healing was impaired as compared to nondiabetic rats; CGS-21680 significantly increased the rate of wound healing in both nondiabetic and diabetic rats. Indeed, the rate of wound healing in the CGS-21680-treated diabetic rats was greater than or equal to that observed in untreated normal rats. These results appear to constitute the first evidence that a small molecule, such as an adenosine receptor agonist, accelerates wound healing in both normal animals and in animals with impaired wound healing.

The anti-inflammatory mechanism of sulfasalazine is related to adenosine release at inflamed sites

The anti-inflammatory mechanism of sulfasalazine is not well understood. It has recently been shown that sulfasalazine inhibits 5-aminoimidazole-4-carboxamidoribonucleotide (AICAR) transformylase, an enzyme involved in de novo purine biosynthesis. We recently demonstrated that methotrexate promotes intracellular AICAR accumulation, thereby increasing adenosine release and diminishing inflammation, so we tested the hypothesis that sulfasalazine similarly promotes intracellular AICAR accumulation. We studied adenosine release and the state of inflammation in in vitro and in vivo models of the inflammatory process. The adhesion of stimulated neutrophils (FMLP) to endothelial cells preincubated with sulfasalazine was inhibited in a dose-dependent manner. Elimination of extracellular adenosine by addition of adenosine deaminase or inhibition of adenosine by the adenosine A2 receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX) completely reversed the anti-inflammatory effect of sulfasalazine (at concentrations <1 microM in this in vitro model. To determine whether this phenomenon was relevant to inhibition of inflammation in vivo, we studied the effect of sulfasalazine (100 mg/kg/day by gastric gavage for 3 days) on leukocyte accumulation in the murine air pouch model of inflammation. Treatment with sulfasalazine markedly decreased the number of leukocytes that accumulated in the inflamed (carrageenan, 2 mg/ml) air pouch. Injection of either adenosine deaminase or DMPX, but not the A1 receptor antagonist 8-cyclopentyl-dipropylxanthine, significantly reversed the anti-inflammatory effects of sulfasalazine treatment. Sulfasalazine increased the exudate adenosine concentration from 127 +/- 64 nM to 869 +/- 47 nM. Moreover, sulfasalazine treatment promoted a marked increase in splenocyte AICAR concentration from 35 +/- 6 to 96 +/- 3 pmols/10(6) splenocytes, which is consistent with the in vitro observation that sulfasalazine inhibits AICAR transformylase. These results indicate that sulfasalazine, like methotrexate, enhances adenosine release at an inflamed site and that adenosine diminishes inflammation via occupancy of A2 receptors on inflammatory cells. Our studies provide evidence that sulfasalazine and methotrexate may be described as a newly recognized family of anti-inflammatory agents that share the property of using adenosine as an antagonist of inflammation.

The anti-inflammatory mechanism of sulfasalazine is related to adenosine release at inflamed sites

The anti-inflammatory mechanism of sulfasalazine is not well understood. It has recently been shown that sulfasalazine inhibits 5-aminoimidazole-4-carboxamidoribonucleotide (AICAR) transformylase, an enzyme involved in de novo purine biosynthesis. We recently demonstrated that methotrexate promotes intracellular AICAR accumulation, thereby increasing adenosine release and diminishing inflammation, so we tested the hypothesis that sulfasalazine similarly promotes intracellular AICAR accumulation. We studied adenosine release and the state of inflammation in in vitro and in vivo models of the inflammatory process. The adhesion of stimulated neutrophils (FMLP) to endothelial cells preincubated with sulfasalazine was inhibited in a dose-dependent manner. Elimination of extracellular adenosine by addition of adenosine deaminase or inhibition of adenosine by the adenosine A2 receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX) completely reversed the anti-inflammatory effect of sulfasalazine (at concentrations <1 microM in this in vitro model. To determine whether this phenomenon was relevant to inhibition of inflammation in vivo, we studied the effect of sulfasalazine (100 mg/kg/day by gastric gavage for 3 days) on leukocyte accumulation in the murine air pouch model of inflammation. Treatment with sulfasalazine markedly decreased the number of leukocytes that accumulated in the inflamed (carrageenan, 2 mg/ml) air pouch. Injection of either adenosine deaminase or DMPX, but not the A1 receptor antagonist 8-cyclopentyl-dipropylxanthine, significantly reversed the anti-inflammatory effects of sulfasalazine treatment. Sulfasalazine increased the exudate adenosine concentration from 127 +/- 64 nM to 869 +/- 47 nM. Moreover, sulfasalazine treatment promoted a marked increase in splenocyte AICAR concentration from 35 +/- 6 to 96 +/- 3 pmols/10(6) splenocytes, which is consistent with the in vitro observation that sulfasalazine inhibits AICAR transformylase. These results indicate that sulfasalazine, like methotrexate, enhances adenosine release at an inflamed site and that adenosine diminishes inflammation via occupancy of A2 receptors on inflammatory cells. Our studies provide evidence that sulfasalazine and methotrexate may be described as a newly recognized family of anti-inflammatory agents that share the property of using adenosine as an antagonist of inflammation.

Isolation and partial characterization of hyaluronan-protein-collagen complex (HA-PC) from fetal sheep skin of different gestational ages

Hyaluronic acid (HA) has a positive effect on cell migration, differentiation and wound healing. Earlier work from our laboratory has shown the presence of biologically active proteins associated with HA. The protein associated with HA of fetal sheep skin varies in molecular weight depending on its gestational age. Specifically, the protein profile changes at 125 days of gestation, from a 60 KDa protein to a smaller protein of about 21 KDa. This time period coincides with the time that scarring becomes apparent in fetal sheep skin wounds. In this study, we have quantified changes in the proteins associated with HA with increasing gestational age, obtained amino acid profiles of these proteins with increasing gestational age, and proposed the existence of an HA-associated protein-collagen complex (HA-PC) which may serve as a scaffold for wound healing. Our results indicate that HA-PC content decreases from 42% of the dry weight at 75 days of gestation to 22% at 125 days of gestation. Protein content, in contrast, increases to 40% of the dry weight at 140 days of gestation. At the same time, collagen content increases from < 1% of the dry weight at 75 days to > 10% at 140 days. The increase in collagen content may account for the increase in total protein seen at 140 days. The expression of varying HA-PC's at different gestational ages may influence the kinetics of collagen fibrillogenesis and thus account for the previously noted late gestational change from "scarless" wound healing to "adult-like" wound healing in fetal sheep.

Anetoderma and human immunodeficiency virus infection

BACKGROUND

Autoimmune disorders such as vitiligo and alopecia areata have been reported in persons infected with the human immunodeficiency virus (HIV).

OBSERVATIONS

Three HIV-infected men had anetoderma develop early in the course of their HIV infection. In two patients this preceded other features of HIV disease, and in the third it occurred while the helper T-cell count exceeded 200/mm3.

CONCLUSIONS

These findings suggest that anetoderma may be an early manifestation of HIV disease, perhaps autoimmune in its pathogenesis.

[Animal models for investigating the possibility of cleft lip surgery in utero]

The continuous refinement and further development of prenatal diagnostics and of anesthesiologic as well as operative techniques have rendered fetal surgery a point of major clinical interest. In view of the present clinical results of prenatal surgery in the human fetus, the question arises, if it is wise to include the correction of craniofacial malformations in the indications for intrauterine surgery and thus to allow the qualitative advantages of fetal wound healing patterns to be utilized. In the present experimental study an animal model using rabbits is presented, which allows successful intrauterine surgery of the craniofacial area.

Neonatal model of heterotopic heart transplantation in pigs

To investigate the long-term success of heart transplantation in newborn infants who have complex congenital heart disease, we have developed a model of heterotopic heart transplantation in immature pigs. We chose the heterotopic technique because it is simple, does not require cardiopulmonary bypass or heparin, allows for significant size disparity between the recipient and donor hearts, and allows for experimental comparisons between the two hearts. Small newborn piglet hearts are harvested, prepared, and then transplanted into the left chest of larger weanling pigs to augment or substitute for the native left ventricle. Preliminary data from transplants into 49 pigs suggest that the technique is technically possible, the pigs can be immunosuppressed over the long term, and the donor heart can contribute hemodynamically. Experimentally, the model is well designed for the investigation of issues critical for the long-term success of heart transplantation in infants and children, including growth and development, optimal long-term immunosuppression, differences in immunotolerance, and the study of coronary obliterative disease. Clinically, the model has potential applicability in congenital heart anomalies if one native functioning atrium and ventricle are present.

Bilateral renal autotransplantation with pyelovesicostomy: a surgical treatment of refractory enteric hyperoxaluria

A 38-year-old man, with only 3 feet of small bowel remaining after multiple resections because of chronic inflammatory bowel disease, had severe symptomatic calcium oxalate nephroureterolithiasis. Because of the refractory symptoms, he was successfully treated with bilateral autotransplantation of the kidneys, totally bypassing the ureters. Anatomically effective urinary tract continuity was reestablished by means of bilateral pyelovesicostomies with concomitant rectus muscle vesicofixation to create direct stone-dumping channels into the urinary bladder. The patient is now completely without symptoms 18 months after surgery. A description and rationale for this surgical treatment is provided. Bilateral autotransplantation of the kidneys with direct drainage into the urinary bladder may be an attractive and viable therapeutic option in complicated patients with short-gut syndrome and severe refractory calcium oxalate nephroureterolithiasis.