Del1 Is a Growth Factor for Skeletal Progenitor Cells in the Fracture Callus

Failure to properly form bone or integrate surgical implants can lead to morbidity and additional surgical interventions in a significant proportion of orthopedic surgeries. While the role of skeletal stem cells (SSCs) in bone formation and repair is well-established, very little is known about the factors that regulate the downstream Bone, Cartilage, Stromal, Progenitors (BCSPs). BCSPs, as transit amplifying progenitor cells, undergo multiple mitotic divisions to expand the pool of lineage committed progenitors allowing stem cells to preserve their self-renewal and stemness. Del1 is a protein widely expressed in the skeletal system, but its deletion led to minimal phenotype changes in the uninjured mouse. In this paper, we demonstrate that Del1 is a key regulator of BCSP expansion following injury. In Del1 knockout mice, there is a significant reduction in the number of BCSPs which leads to a smaller callus and decreased bone formation compared with wildtype (WT) littermates. Del1 serves to promote BCSP proliferation and prevent apoptosis in vivo and in vitro. Moreover, exogenous Del1 promotes proliferation of aged human BCSPs. Our results highlight the potential of Del1 as a therapeutic target for improving bone formation and implant success. Del1 injections may improve the success of orthopedic surgeries and fracture healing by enhancing the proliferation and survival of BCSPs, which are crucial for generating new bone tissue during the process of bone formation and repair.

Sexually dimorphic estrogen sensing in skeletal stem cells controls skeletal regeneration

Sexually dimorphic tissues are formed by cells that are regulated by sex hormones. While a number of systemic hormones and transcription factors are known to regulate proliferation and differentiation of osteoblasts and osteoclasts, the mechanisms that determine sexually dimorphic differences in bone regeneration are unclear. To explore how sex hormones regulate bone regeneration, we compared bone fracture repair between adult male and female mice. We found that skeletal stem cell (SSC) mediated regeneration in female mice is dependent on estrogen signaling but SSCs from male mice do not exhibit similar estrogen responsiveness. Mechanistically, we found that estrogen acts directly on the SSC lineage in mice and humans by up-regulating multiple skeletogenic pathways and is necessary for the stem cell's ability to self- renew and differentiate. Our results also suggest a clinically applicable strategy to accelerate bone healing using localized estrogen hormone therapy.

Local and Visiting Physician Perspectives on Short Term Surgical Missions in Guatemala: A Qualitative Study

OBJECTIVE

To explore the impact of short-term surgical missions (STMs) on medical practice in Guatemala as perceived by Guatemalan and foreign physicians.

SUMMARY BACKGROUND DATA

STMs send physicians from high-income countries to low and middle-income countries to address unmet surgical needs. Although participation among foreign surgeons has grown, little is known of the impact on the practice of foreign or local physicians.

METHODS

Using snowball sampling, we interviewed 22 local Guatemalan and 13 visiting foreign physicians regarding their perceptions of the impact of Guatemalan STMs. Interviews were transcribed verbatim, iteratively coded, and analyzed to identify emergent themes. Findings were validated through triangulation and searching for disconfirming evidence.

RESULTS

We identified 2 overarching domains. First, the delivery of surgical care by both Guatemalan and foreign physicians was affected by practice in the STM setting. Differences from usual practice manifested as occasionally inappropriate utilization of skills, management of postoperative complications, the practice of perioperative care versus "pure surgery," and the effect on patient-physician communication and trust. Second, both groups noted professional and financial implications of participation in the STM.

CONCLUSIONS

While Guatemalan physicians reported a net benefit of STMs on their careers, they perceived STMs as an imperfect solution to unmet surgical needs. They described missed opportunities for developing local capacity, for example through education and optimal resource planning. Foreign physicians described costs that were manageable and high personal satisfaction with STM work. STMs could enhance their impact by strengthening working relationships with local physicians and prioritizing sustainable educational efforts.

[Effect of imatinib on the height of children with chronic myeloid leukemia in the chronic phase]

目的

评估伊马替尼对慢性髓性白血病慢性期（CML-CP）儿童身高的影响。

方法

2018年7月至2019年7月，在全国范围内对诊断时年龄<18周岁、接受伊马替尼治疗至少3个月的CML儿童或其家长发放问卷，调查受访者伊马替尼治疗前后身高的变化。主要评价指标为身高标准差积分值（HtSDS）以及标准差积分的差值（ΔHtSDS），并分析其相关影响因素。

结果

共有238例受访者符合标准并被纳入研究，男性138例（58.0％），初诊时中位年龄11.0（1.4～17.9）岁，青春期前93例（39.0％），至填写答卷时，中位年龄15.0（2.0～34.0）岁，中位伊马替尼服药时间28（3～213）个月。受访者填写答卷时HtSDS（−0.063±1.361）较治疗前HtSDS（0.391±1.244）显著下降（P<0.001），71.0％的患儿出现身高增长减慢。青春期前服药者治疗后HtSDS下降显著（P<0.05），而青春期开始后服药者HtSDS变化不明显（P>0.05）。多因素分析显示，服药初始年龄较小（偏回归系数为0.122，B＝0.572，t＝10.733，P<0.001）和服药时间较长（偏回归系数为−0.006，B＝−0.211，t＝−4.062，P<0.001）是伊马替尼抑制身高增长的独立影响因素。

结论

伊马替尼引起CML-CP儿童身高增长障碍，服药初始年龄越小、服药时间越长，伊马替尼对身高的影响越明显。

Correction to: Strengthening Surgery Strengthens Health Systems: A New Paradigm and Potential Pathway for Horizontal Development in Low- and Middle-Income Countries

In the original article, Ziad C. Sifri's first and last names were interchanged. It is correct as reflected here.

Lost in translation: Informed consent in the medical mission setting

BACKGROUND

Informed consent is a fundamental tenet of ethical care, but even under favorable conditions, patient comprehension of consent conversations may be limited. Little is known about providing informed consent in more uncertain situations such as medical missions. We sought to examine the informed consent process in the medical mission setting.

METHODS

We studied informed consent for adult patients undergoing inguinal herniorrhaphy during a medical mission to Guatemala using a convergent mixed-methods design. We audiotaped informed consents during preoperative visits and immediately conducted separate surveys to elicit comprehension of risks. Informed consent conversations and survey responses were translated and transcribed. We used descriptive statistics to examine informed consent content, including information provided by surgeon, the translation of information, and patient comprehension, and used thematic analysis to examine the consent process.

RESULTS

Thirteen adult patients (median age 53 years, 69% male) participated. Surgeons conveyed 4 standard risks in 10 out of 13 encounters (77%); all 4 risks were translated to patients in 10 out of 13 encounters (77%). No patient could recall all 4 risks. Qualitative themes regarding the informed consent process included limited physician language skills, verbal domination by physicians and interpreters, and mistranslation of risks. Patients relied on faith and prior or vicarious experiences to qualify surgical risks instead of consent conversations. Many patients restated surgical instructions when asked about risks.

CONCLUSION

Despite physicians' attempts to provide informed consent, medical mission patients did not comprehend surgical risks. Our data reveal a critical need to develop more effective methods for communicating surgical risks during medical missions.

DEL1 protects against chondrocyte apoptosis through integrin binding

BACKGROUND

Osteoarthritis (OA) is a debilitating disease process, affecting mobility and overall health of millions. Current treatment is for symptomatic relief and discovery of approaches to halt or reverse damage is imperative. Deletion of developmental endothelial locus-1 (Del1) has been shown to increase severity of OA in knockout mice. We examined the intracellular pathways involved in the ability of DEL1 to protect chondrocytes from apoptosis and anoikis and hypothesized that it functioned via integrin signaling.

MATERIALS AND METHODS

Primary human chondrocytes were treated with various inducers of apoptosis, including anoikis, in the presence of added DEL1 or bovine serum albumin as control. Various inhibitors of integrin binding were examined for their effect on DEL1 activity. Downstream signaling pathway components were detected by immunoblotting.

RESULTS

The addition of DEL1 protected chondrocytes from multiple inducers of apoptosis as measured by cell survival, terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase 3/7 assays (P < 0.05). The effect of DEL1 was blocked by RGD peptides and by antibodies directed to integrin α_Vβ₃, but not by controls or antibody to integrin α1 (P < 0.05). Treatment with DEL1 promoted ERK and AKT activation when cells were attached, but only AKT activation under conditions of anoikis.

CONCLUSIONS

DEL1 protected chondrocytes from apoptosis in response to activators of either the intrinsic or extrinsic pathways, and to anoikis. This effect was mediated primarily through integrin α_Vβ₃. This represents a therapeutic target for therapies to prevent cartilage degeneration in OA.

Inhibition of IRE1 results in decreased scar formation

Wound healing is characterized by the production of large amounts of protein necessary to replace lost cellular mass and extracellular matrix. The unfolded protein response (UPR) is an important adaptive cellular response to increased protein synthesis. One of the main components of the UPR is IRE1, an endoplasmic reticulum transmembrane protein with endonuclease activity that produces the activated form of the transcription factor XBP1. Using luciferase reporter mice for Xbp1 splicing, we showed that IRE1 was up-regulated during excisional wound healing at the time in wound healing consistent with that of the proliferative phase, when the majority of protein synthesis for cellular proliferation and matrix deposition occurs. Furthermore, using a small molecule inhibitor of IRE1 we demonstrated that inhibition of IRE1 led to decreased scar formation in treated mice. Results were recapitulated in a hypertrophic scar mouse model. These data help provide a cellular pathway to target in the treatment of hypertrophic scarring and keloid disorders.

Review of the Current Management of Pressure Ulcers

Significance: The incidence of pressure ulcers is increasing due to our aging population and the increase in the elderly living with disability. Learning how to manage pressure ulcers appropriately is increasingly important for all professionals in wound care. Recent Advances: Many new dressings and treatment modalities have been developed over the recent years and the goal of this review is to highlight their benefits and drawbacks to help providers choose their tools appropriately. Critical Issues: Despite an increased number of therapies available on the market, none has demonstrated any clear benefit over the others and pressure ulcer treatment remains frustrating and time-consuming. Future Directions: Additional research is needed to develop products more effective in prevention and treatment of pressure ulcers.

An academic career in global surgery: a position paper from the Society of University Surgeons Committee on Academic Global Surgery

In recent years, as the high burden of surgical disease and poor access to surgical care in low- and middle-income countries have gained recognition as major public health problems, interest in global health has surged among surgical trainees and faculty. Traditionally, clinical volunteerism was at the forefront of the high-income country response to the significant burden of surgical disease in low- and middle-income countries. However, sustainable strategies for providing surgical care in low- and middle-income countries increasingly depend on bilateral clinical, research, and education collaborations to ensure effective resource allocation and contextual relevance. Academic global surgery creates avenues for interested surgeons to combine scholarship and education with their clinical global surgery passions through incorporation of basic/translational, education, clinical outcomes, or health services research with global surgery. Training in global health, either within residency or through advanced degrees, can provide the necessary skills to develop and sustain such initiatives. We further propose that creating cross-continental, bidirectional collaborations can maximize funding opportunities. Academic institutions are uniquely positioned to lead longitudinal and, importantly, sustainable global surgery efforts. However, for the individual global surgeon, the career path forward may be unclear. This paper reviews the development of academic global surgery, delineates the framework and factors critical to training global surgeons, and proposes models for establishing an academic career in this field. Overall, with determination, the academic global surgeon will not only carve out a niche of expertise but will define this critical field for future generations.

Guide to research in academic global surgery: A statement of the Society of University Surgeons Global Academic Surgery Committee

Global surgery is an emerging academic discipline that is developing in tandem with numerous policy and advocacy initiatives. In this regard, academic global surgery will be crucial for measuring the progress toward improving surgical care worldwide. However, as a nascent academic discipline, there must be rigorous standards for the quality of work that emerges from this field. In this white paper, which reflects the opinion of the Global Academic Surgery Committee of the Society for University Surgeons, we discuss the importance of research in global surgery, the methodologies that can be used in such research, and the challenges and benefits associated with carrying out this research. In each of these topics, we draw on existing examples from the literature to demonstrate our points. We conclude with a call for continued, high-quality research that will strengthen the discipline's academic standing and help us move toward improved access to and quality of surgical care worldwide.

Laboratory Models for the Study of Normal and Pathologic Wound Healing

Current knowledge of wound healing is based on studies using various in vitro and in vivo wound models. In vitro models allow for biological examination of specific cell types involved in wound healing. In vivo models generally provide the full spectrum of biological responses required for wound healing, including inflammation and angiogenesis, and provide cell-cell interactions not seen in vitro. In this review, the authors aim to delineate the most relevant wound healing models currently available and to discuss their strengths and limitations in their approximation of the human wound healing processes to aid scientists in choosing the most appropriate wound healing models for designing, testing, and validating their experiments.

Why do patients receive care from a short-term medical mission? Survey study from rural Guatemala

BACKGROUND

Hospital de la Familia was established to serve the indigent population in the western highlands of Guatemala and has a full-time staff of Guatemalan primary care providers supplemented by short-term missions of surgical specialists. The reasons for patients seeking surgical care in this setting, as opposed to more consistent care from local institutions, are unclear. We sought to better understand motivations of patients seeking mission-based surgical care.

METHODS

Patients presenting to the obstetric and gynecologic, plastic, ophthalmologic, general, and pediatric surgical clinics at the Hospital de la Familia from July 27 to August 6, 2015 were surveyed. The surveys assessed patient demographics, surgical diagnosis, location of home, mode of travel, and reasons for seeking care at this facility.

RESULTS

Of 252 patients surveyed, 144 (59.3%) were female. Most patients reported no other medical condition (67.9%, n = 169) and no consistent income (83.9%, n = 209). Almost half (44.9%, n = 109) traveled >50 km to receive care. The most common reasons for choosing care at this facility were reputation of high quality (51.8%, n = 130) and affordability (42.6%, n = 102); the least common reason was a lack of other options (6.4%, n = 16).

CONCLUSIONS

Despite long travel distances and the availability of other options, reputation and affordability were primarily cited as the most common reasons for choosing to receive care at this short-term surgical mission site. Our results highlight that although other surgical options may be closer and more readily available, reputation and cost play a large role in choice of patients seeking care.

Del1 Knockout Mice Developed More Severe Osteoarthritis Associated with Increased Susceptibility of Chondrocytes to Apoptosis

OBJECTIVE

We identified significant expression of the matricellular protein, DEL1, in hypertrophic and mature cartilage during development. We hypothesized that this tissue-specific expression indicated a biological role for DEL1 in cartilage biology.

METHODS

Del1 KO and WT mice had cartilage thickness evaluated by histomorphometry. Additional mice underwent medial meniscectomy to induce osteoarthritis, and were assayed at 1 week for apoptosis by TUNEL staining and at 8 weeks for histology and OA scoring. In vitro proliferation and apoptosis assays were performed on primary chondrocytes.

RESULTS

Deletion of the Del1 gene led to decreased amounts of cartilage in the ears and knee joints in mice with otherwise normal skeletal morphology. Destabilization of the knee led to more severe OA compared to controls. In vitro, DEL1 blocked apoptosis in chondrocytes.

CONCLUSION

Osteoarthritis is among the most prevalent diseases worldwide and increasing in incidence as our population ages. Initiation begins with an injury resulting in the release of inflammatory mediators. Excessive production of inflammatory mediators results in apoptosis of chondrocytes. Because of the limited ability of chondrocytes to regenerate, articular cartilage deteriorates leading to the clinical symptoms including severe pain and decreased mobility. No treatments effectively block the progression of OA. We propose that direct modulation of chondrocyte apoptosis is a key variable in the etiology of OA, and therapies aimed at preventing this important step represent a new class of regenerative medicine targets.

A distinct regulatory region of the Bmp5 locus activates gene expression following adult bone fracture or soft tissue injury

Bone morphogenetic proteins (BMPs) are key signaling molecules required for normal development of bones and other tissues. Previous studies have shown that null mutations in the mouse Bmp5 gene alter the size, shape and number of multiple bone and cartilage structures during development. Bmp5 mutations also delay healing of rib fractures in adult mutants, suggesting that the same signals used to pattern embryonic bone and cartilage are also reused during skeletal regeneration and repair. Despite intense interest in BMPs as agents for stimulating bone formation in clinical applications, little is known about the regulatory elements that control developmental or injury-induced BMP expression. To compare the DNA sequences that activate gene expression during embryonic bone formation and following acute injuries in adult animals, we assayed regions surrounding the Bmp5 gene for their ability to stimulate lacZ reporter gene expression in transgenic mice. Multiple genomic fragments, distributed across the Bmp5 locus, collectively coordinate expression in discrete anatomic domains during normal development, including in embryonic ribs. In contrast, a distinct regulatory region activated expression following rib fracture in adult animals. The same injury control region triggered gene expression in mesenchymal cells following tibia fracture, in migrating keratinocytes following dorsal skin wounding, and in regenerating epithelial cells following lung injury. The Bmp5 gene thus contains an "injury response" control region that is distinct from embryonic enhancers, and that is activated by multiple types of injury in adult animals.

Moisturizing different racial skin types

The skin is a complex organ involved in thermoregulation, gas exchange, protection against pathogens, and barrier function to maintain proper hydration. When dry, the ability for skin to execute these tasks becomes impaired. Dry skin affects almost everyone as we age, but it is also dependent on external factors, such as dry climate, colder temperatures, and repeated washing. In addition, increasing evidence has shown racial variability in the physiological properties of skin, which directly impacts water content of the stratum corneum and sensitivity to exogenously applied agents. A multitude of products have been developed to treat dry skin, and as a group, moisturizers have been designed to either impart or restore hydration in the stratum corneum. Given the large number of moisturizers presently available, depending on individual components, several different mechanisms may be employed to promote skin hydration. As there exists dramatic racial variability in skin properties, certain moisturizers may thus be more effective in some and less effective in others to treat the common condition of dry skin.

Revealing the contribution of Cytochrome P450 to salt-sensitive hypertension using DNA microarray

BACKGROUND

Salt sensitivity is an important cause of hypertension which is a major public health problem. This study aimed to investigate the contribution of Cytochrome P450 (CYP) to salt-sensitive hypertension with microarray data and bioinformatics analysis.

METHODS

Gene expression data set GSE4800 was downloaded from Gene Expression Omnibus database, including 6 gene chips from 3 Dahl salt sensitive (DS) rat samples and 3 Lewis (LEW) rat samples. Raw data were preprocessed and normalized, and then differentially expressed genes (DEGs) were identified with Limma package. Interaction network was constructed by employing STRING (Search Tool for the Retrieval of Interacting Genes) tool. GO (Gene Ontology) enrichment analysis was performed using FuncAssociate tool and pathway analysis was carried out by EASE (Expressing Analysis Systematic Explorer). BLAST (Basic Local Alignment Search Tool) was applied to explore the sequence homology among CYP3A genes in rat and human based on multiple alignments.

RESULTS

A total of 1264 DEGs, including 1082 up-regulated genes and 182 down-regulated genes were identified between DS and LEW samples. CYP3A2 and CYP3A9 were selected to construct the protein interaction network, which comprised 1653 pairs of interaction relationship among 100 genes. Functional analysis showed that CYP3A2 and CYP3A9 were most significantly related to oxidation reduction and metabolism of xenobiotics by cytochrome P450. Furthermore, the CYP3A2 and CYP3A9 genes in rats had high homology with genes CYP3A4and CYP3A5 in human beings.

CONCLUSIONS

CYP3A4 and CYP3A5 may contribute to salt-sensitive hypertension in human which may act as biomarkers for this disease.

The angiogenic factor Del1 prevents apoptosis of endothelial cells through integrin binding

BACKGROUND

Del1 is a secreted protein that is expressed in the endothelium during development and can stimulate angiogenesis through integrin binding and signaling. We were interested in the specific effects of del1 on endothelial cell biology to gain insight into its biologic role during angiogenesis.

METHODS

Primary endothelial cells were treated with a variety of inducers of apoptosis and anoikis followed by assays for numbers of apoptotic cells, and harvest of total protein for immunoblot analysis.

RESULTS

Del1 prevented endothelial cell apoptosis in response to TNFα/IFNγ, etoposide, and anoikis, but had no effect on proliferation. The anti-apoptotic effect was mediated specifically through binding of integrin αvβ3 by the RGD motif. FAK/ERK and Akt signaling were both necessary to mediate the anti-apoptotic effect of Del1 with the exception of anoikis, which required only Akt activation.

CONCLUSION

Del1 has been previously shown to promote vascular smooth muscle cell adhesion, migration, and proliferation. We demonstrate here that Del1 prevented apoptosis of endothelial cells in cell culture through integrin binding without any effect on proliferation.

Engineered epidermal growth factor mutants with faster binding on-rates correlate with enhanced receptor activation

Receptor tyrosine kinases (RTKs) regulate critical cell signaling pathways, yet the properties of their cognate ligands that influence receptor activation are not fully understood. There is great interest in parsing these complex ligand-receptor relationships using engineered proteins with altered binding properties. Here we focus on the interaction between two engineered epidermal growth factor (EGF) mutants and the EGF receptor (EGFR), a model member of the RTK superfamily. We found that EGF mutants with faster kinetic on-rates stimulate increased EGFR activation compared to wild-type EGF. These findings support previous predictions that faster association rates correlate with enhanced receptor activity.

Comparative healing of rat fascia following incision with three surgical instruments

BACKGROUND

Incisional hernia and fascial dehiscence are associated with significant postoperative morbidity. Electrosurgical devices using pulsed radiofrequency energy and a novel electrode design markedly reduce thermal injury during cutting and coagulation while maintaining equal surgical performance. In this study, we examine fascial healing dynamics in a rat model following incision with a pulsed radiofrequency energy device (PRE), a conventional electrosurgical device, and a standard "cold" scalpel. We hypothesize that incisions made with the pulsed radiofrequency energy device will result in a superior fascial healing profile compared with conventional electrosurgery.

MATERIALS AND METHODS

Full thickness surgical incisions were created in rat fascia using a commercially available PRE device, conventional electrosurgery, and a scalpel. Harvested fascial specimens were analyzed for burst strength testing and healing-associated histologic characteristics at d 7, 14, 21, and 42.

RESULTS

PRE incisions were fully healed by 6 wk with normal tissue architecture. By all measures, wounds created by the PRE device were comparable to those made with the standard scalpel. Compared with PRE, conventional electrosurgery incisions exhibited a larger zone of tissue injury (68% greater in Coag mode, P < 0.0001; 46% greater in Cut mode, P < 0.001), an increased inflammatory response and a less favorable wound architecture. In the immediate postoperative period (1 wk), burst strength testing demonstrated that PRE fascial wounds were significantly stronger than those made by electrosurgery in Coag mode (318%, P = 0.001).

CONCLUSIONS

The favorable fascial healing profile of the PRE device suggests that it is a promising new surgical technology. The early improved strength of wounds made with this device is of particular interest, as wound dehiscence is of greatest concern early in the healing process.

Human melanoma-initiating cells express neural crest nerve growth factor receptor CD271

The question of whether tumorigenic cancer stem cells exist in human melanomas has arisen in the last few years. Here we show that in melanomas, tumour stem cells (MTSCs, for melanoma tumour stem cells) can be isolated prospectively as a highly enriched CD271(+) MTSC population using a process that maximizes viable cell transplantation. The tumours sampled in this study were taken from a broad spectrum of sites and stages. High-viability cells isolated by fluorescence-activated cell sorting and re-suspended in a matrigel vehicle were implanted into T-, B- and natural-killer-deficient Rag2(-/-)gammac(-/-) mice. The CD271(+) subset of cells was the tumour-initiating population in 90% (nine out of ten) of melanomas tested. Transplantation of isolated CD271(+) melanoma cells into engrafted human skin or bone in Rag2(-/-)gammac(-/-) mice resulted in melanoma; however, melanoma did not develop after transplantation of isolated CD271(-) cells. We also show that in mice, tumours derived from transplanted human CD271(+) melanoma cells were capable of metastatsis in vivo. CD271(+) melanoma cells lacked expression of TYR, MART1 and MAGE in 86%, 69% and 68% of melanoma patients, respectively, which helps to explain why T-cell therapies directed at these antigens usually result in only temporary tumour shrinkage.

The role of tumor cell-derived connective tissue growth factor (CTGF/CCN2) in pancreatic tumor growth

Pancreatic cancer is highly aggressive and refractory to existing therapies. Connective tissue growth factor (CTGF/CCN2) is a fibrosis-related gene that is thought to play a role in pancreatic tumor progression. However, CCN2 can be expressed in a variety of cell types, and the contribution of CCN2 derived from either tumor cells or stromal cells as it affects the growth of pancreatic tumors is unknown. Using genetic inhibition of CCN2, we have discovered that CCN2 derived from tumor cells is a critical regulator of pancreatic tumor growth. Pancreatic tumor cells derived from CCN2 shRNA-expressing clones showed dramatically reduced growth in soft agar and when implanted s.c. We also observed a role for CCN2 in the growth of pancreatic tumors implanted orthotopically, with tumor volume measurements obtained by positron emission tomography imaging. Mechanistically, CCN2 protects cells from hypoxia-mediated apoptosis, providing an in vivo selection for tumor cells that express high levels of CCN2. We found that CCN2 expression and secretion was increased in hypoxic pancreatic tumor cells in vitro, and we observed colocalization of CCN2 and hypoxia in pancreatic tumor xenografts and clinical pancreatic adenocarcinomas. Furthermore, we found increased CCN2 staining in clinical pancreatic tumor tissue relative to stromal cells surrounding the tumor, supporting our assertion that tumor cell-derived CCN2 is important for pancreatic tumor growth. Taken together, these data improve our understanding of the mechanisms responsible for pancreatic tumor growth and progression, and also indicate that CCN2 produced by tumor cells represents a viable therapeutic target for the treatment of pancreatic cancer.

Gemcitabine chemotherapy and single-fraction stereotactic body radiotherapy for locally advanced pancreatic cancer

PURPOSE

Fractionated radiotherapy and chemotherapy for locally advanced pancreatic cancer achieves only modest local control. This prospective trial evaluated the efficacy of a single fraction of 25 Gy stereotactic body radiotherapy (SBRT) delivered between Cycle 1 and 2 of gemcitabine chemotherapy.

METHODS AND MATERIALS

A total of 16 patients with locally advanced, nonmetastatic, pancreatic adenocarcinoma received gemcitabine with SBRT delivered 2 weeks after completion of the first cycle. Gemcitabine was resumed 2 weeks after SBRT and was continued until progression or dose-limiting toxicity. The gross tumor volume, with a 2-3-mm margin, was treated in a single 25-Gy fraction by Cyberknife. Patients were evaluated at 4-6 weeks, 10-12 weeks, and every 3 months after SBRT.

RESULTS

All 16 patients completed SBRT. A median of four cycles (range one to nine) of chemotherapy was delivered. Three patients (19%) developed local disease progression at 14, 16, and 21 months after SBRT. The median survival was 11.4 months, with 50% of patients alive at 1 year. Patients with normal carbohydrate antigen (CA)19-9 levels either at diagnosis or after Cyberknife SBRT had longer survival (p <0.01). Acute gastrointestinal toxicity was mild, with 2 cases of Grade 2 (13%) and 1 of Grade 3 (6%) toxicity. Late gastrointestinal toxicity was more common, with five ulcers (Grade 2), one duodenal stenosis (Grade 3), and one duodenal perforation (Grade 4). A trend toward increased duodenal volumes radiated was observed in those experiencing late effects (p = 0.13).

CONCLUSION

SBRT with gemcitabine resulted in comparable survival to conventional chemoradiotherapy and good local control. However, the rate of duodenal ulcer development was significant.

Use of organotypic coculture to study keloid biology

BACKGROUND

Keloids are pathologic scars afflicting a large segment of our population and for which there is no definitive therapy. The lack of an animal model for keloid formation has hampered study. We developed an in vitro organotypic skin model to simulate normal keloid biology, which may allow us to study keloid formation without an animal model.

METHODS

Normal (NFs) and keloid (KFs) human fibroblasts were cultured in a collagen matrix to create a 3-dimensional dermal structure. Normal human keratinocytes (NKs) were cultured as a second layer on top and exposed to an air-fluid interface to allow differentiation into a mature keratinocyte layer. The organotypic skin was maintained for 28 days in Dulbecco's modified eagle medium with 10% fetal calf serum. Samples were collected, processed, sectioned, stained with hematoxylin and eosin, and then measured for qualitative analysis. alpha-smooth-muscle actin was also evaluated by immunoblotting.

RESULTS

KF/NK organotypic skin showed increased collagen deposition, based on significantly denser collagen staining, with increased dermal thickness compared with NF/NK organotypic skin. We saw increased contracture in the KF/NK construct, and this correlated with increased organization of alpha-smooth-muscle actin fibers in the dermal layer of KF/NK organotypic skin compared with NF/NK skin.

CONCLUSIONS

We have shown that coculture of KFs with keloid keratinocytes leads to an increased collagen production and dermal contracture compared with NFs and NKs, consistent with known keloid behavior. Given the lack of an animal model, we believe that organotypic skin culture can serve as a surrogate to study keloid formation.

Increased rate of hair regrowth in mice with constitutive overexpression of Del1

BACKGROUND

Developmental endothelial locus (Del)1 is a secreted extracellular matrix-associated protein that stimulates angiogenesis through integrin binding and is implicated in vasculogenesis. We hypothesized that increased expression of an angiogenic factor would lead to enhanced wound healing.

MATERIALS AND METHODS

Transgenic mice had Del1 cloned behind a keratin 14 promoter (K14-Del1) to drive constitutive expression in basal keratinocytes. Transgenic animals and wild-type litter mates underwent excisional wounding or depilation, and tissues were harvested at various time points. Wound healing and hair regrowth were assessed by photography, histology, and immunohistochemistry. For injection experiments, purified Del1 protein was injected in the flanks of wild-type mice with carrier on the contralateral flank as a control. Del1 expression during hair development was performed using transgenic mice with a LacZ cassette introduced downstream from the native promoter.

RESULTS

K14-Del1 animals appeared normal and healed excisional wounds normally but demonstrated an increased rate of hair regrowth after wound healing. Using depilation experiments to specifically address hair follicle growth, we found increased hair regrowth was independent of wounding. This was confirmed by injection of purified Del1 protein. During normal hair anagenesis, Del1 is expressed in the root of the hair follicle.

CONCLUSIONS

Constitutive expression of Del1 in skin does not affect skin vascularity or improve wound healing. Surprisingly, we found the primary effect of constitutive Del1 expression in the basal keratinocytes was increased hair growth following induction of anagenesis. During normal hair anagenesis, we see expression of Del1 in the root of the hair follicle suggesting it may function there to stimulate hair growth.

Treatment of oesophageal ulcerations using endoscopic transplantation of tissue-engineered autologous oral mucosal epithelial cell sheets in a canine model

Endoscopic transplantation in oesophageal ulceration

Stereotactic body radiotherapy for unresectable pancreatic cancer

Pancreatic cancer is a devastating disease with few effective treatment modalities. Recent technological advances have made possible the delivery of single-fraction stereotactic body radiotherapy (SBRT) to patients with locally advanced pancreatic tumors. This paper presents experience at Stanford University with SBRT for patients with unresectable pancreatic cancer. Pancreatic tumors of up to 100 cm3 could be treated. Patients achieved greater than 90% local control for the remainder of their lives. Currently, the standard dose for pancreatic tumors treated at this institution is 25 Gy given in a single fraction. Four-dimensional CT and PET scans have been essential for optimal treatment planning. PET-CT scanning may be a more effective method for evaluating tumor response than conventional CT scanning. Adjuvant systemic therapies could be administered in coordination with SBRT. SBRT is an effective method of treating patients resulting in excellent local control. Current research is aimed at defining the optimal method of combining this treatment with other cancer therapies.

Functions of vitamin D, retinoic acid, and dexamethasone in mouse adipose-derived mesenchymal cells

Adipose-derived mesenchymal cells (AMCs) offer great promise for tissue engineering of bone. Previously, 1,25-dihydroxyvitamin D3, retinoic acid (RA), and dexamethasone had been shown to promote osteogenesis in bone marrow-derived mesenchymal cells (BMSCs). To study the osteogenic characteristics of mouse AMCs, we applied these 3 hormones alone and in combination to the AMCs and examined markers of osteogenic differentiation. Interestingly, vitamin D and RA demonstrated a consistent, dose-dependent enhancement of osteogenesis and upregulated osteoblast specific markers including osteopontin and osteocalcin. However, in AMCs, dexamethasone clearly inhibited osteogenic differentiation in a dose dependent fashion and greatly increased the adipogenic marker peroxisome proliferator activated receptor gamma (PPAgamma). In summary, we show in vitro that vitamin D and RA are potential candidates to serve as enhancers of osteogenesis of AMCs and may be incorporated into future cell-based strategies for bone tissue engineering.

P38 MAP kinase mediates transforming growth factor-beta2 transcription in human keloid fibroblasts

Keloids are abnormal fibrous growths of the dermis that develop only in response to wounding and represent a form of benign skin tumor. Previous studies have shown increased protein levels of TGF-beta in keloid tissue, suggesting a strong association with keloid formation leading us to examine mechanisms for why it is more highly expressed in keloids. Here, we use serum stimulation as an in vitro model to mimic a component of the wound microenvironment and examine differential gene expression in keloid human fibroblasts (KFs) vs. normal human fibroblasts (NFs). Transcription of TGF-beta2 was rapid and peaked between 1 and 6 h after serum stimulation in KFs vs. NFs. We confirmed increased TGF-beta activity in the conditioned medium from KFs, but not NFs. Inhibition of second messenger signaling pathways demonstrated that only the p38 MAPK inhibitor SB-203580 could block upregulation of TGF-beta2 following serum stimulation in KFs. Immunoblotting demonstrated that p38 MAPK was phosphorylated within 15 min and was maintained at a high level in KFs but not in NFs. The transcription factors activating transcription factor-2 and Elk-1 are activated by p38 MAPK, and also showed rapid and prolonged phosphorylation kinetics in KFs but not in NFs. In conclusion, increased TGF-beta2 transcription in response to serum stimulation in KFs appears to be mediated by the p38 MAPK pathway. This suggests the mechanism of keloid pathogenesis may be due in part to an inherent difference in how the fibroblasts respond to wounding.

Differential transcriptional responses of keloid and normal keratinocytes to serum stimulation

BACKGROUND

Keloids are benign tumors that occur only in response to injury, for which there is no effective treatment. We demonstrated previously that keloid keratinocytes (KKs) promote fibroblast proliferation more than normal keratinocytes (NKs) and that transforming growth factor (TGF)-beta is a component of that signal. We used the transcriptional response to serum stimulation to examine how TGF-beta expression is stimulated in KKs.

MATERIALS AND METHODS

Quiescent KKs and NKs were stimulated using serum; harvested using RNA at 0, 1, 6, 12, and 24 h; and analyzed using quantitative real-time polymerase chain reaction. TGF-beta activity in the conditioned medium was measured with an MLEC/PAI-luciferase assay. Inhibition of ERK1/2, p38 kinase, and JNK pathways was performed with PD98059, SB203580, and SP600125, respectively.

RESULTS

Increased transcription of TGF-beta2 occurs within 1 h of serum stimulation in KKs but not in NKs. In contrast, TGF-beta3 transcription was suppressed in KKs compared with NKs. No significant differences were observed in the transcriptional response of TGF-beta1. Increased TGF-beta2 mRNA correlated with increased TGF-beta biological activity in the conditioned medium. Inhibition of the ERK, p38 kinase or JNK signal transduction pathways blocked the transcriptional up-regulation of TGF-beta2, TbetaR1, and TbetaR2 in KKs.

CONCLUSIONS

KKs produce more TGF-beta2 mRNA than NKs in response to serum stimulation, resulting in increased TGF-beta activity in conditioned medium. Combining these results with our previous data lead us to propose a model of keloid formation characterized by an exaggerated response to cellular stress and abnormal epithelial-mesenchymal signaling promoting keloid formation.