Inclusion of person-centred care in UK postgraduate medical education curricula: Interviews and documentary analysis.

BACKGROUND: Person-centred care (PCC) involves placing people at the centre of their healthcare decision making to ensure it meets their needs, values, and personal circumstances. Increasingly, PCC is promoted in healthcare policy and guidance, but little is known about how this is embedded in postgraduate medical training. The aim of this research was to understand how PCC is embedded in UK postgraduate medical training and explore factors influencing inclusion of PCC in curricula content. METHODS: To explore this, we interviewed senior professionals with key roles in the curricula from four UK Royal Colleges (Psychiatrists; Physicians; Surgeons; and GPs) and used framework analysis on interviews and relevant curricula documents to identify themes. RESULTS: Legislation and professional/educational guidance influenced inclusion. PCC definitions and terminology differed and placement within curricula was variable. Royal Colleges defined the curriculum and provided training to ensure competence, but local deaneries independently implemented the curriculum. Trainer engagement was greater than trainee buy in. Quality assurance focused on feedback from trainers and trainees rather than patients, and patient and public involvement in curriculum development, teaching, and assessment was limited. CONCLUSIONS: There is a need for cross-organisation collaboration to develop a PCC competence framework that defines the skills and level of competence required at different points in training, with clarity around the differences between undergraduate and postgraduate requirements. Greater auditing and quality assurance of programme delivery would help identify successful practices to share within and across Royal Colleges, while still maintaining the flexibility of local provision. Engagement with patients and the public in this work can only strengthen provision.

Pyrethroid toxicity in a Vietnamese pot-bellied pig.

A 7-month-old spayed female Vietnamese pot-bellied pig (VPBP) was presented for diffuse muscle fasciculations and seizure-like activity that had started 4 hours before presentation. The pig was stuporous and displayed diffuse involuntary gross motor movement and muscle fasciculations, as well as hypertonicity of all 4 limbs. Hematologic analysis revealed hemoconcentration, severe hyperlactatemia, moderate metabolic acidosis, increased creatine kinase and gamma-glutamyltransferase. The pig failed to respond to diazepam, propofol, methocarbamol, and supportive care, followed by general anesthesia, and was euthanized. Bifenthrin, a pyrethroid insecticide, was identified by gas chromatography-mass spectrometry of stomach contents. Pyrethroid insecticide toxicity in VPBP may result in clinical signs similar to those seen in companion animals.

Toxicité pyréthroïde chez un Cochon vietnamien. Une truie stérilisée Cochon vietnamien (CV) âgée de 7 mois a été présentée pour des fasciculations des muscles diffus et une activité s'apparentant à des crises d'épilepsie qui avaient commencé 4 heures avant la présentation. Le cochon était stuporeux et manifestait des mouvements moteurs diffus et des fasciculations musculaires involontaires ainsi que de l'hypertonicité des quatre membres. Une analyse hématologique a révélé l'hémoconcentration, une hyperlactatémie grave, une acidose métabolique modérée, une kinase de créatine et une gamma-glutamyltransférase élevées. Le cochon n'a pas répondu au diazépam, au propofol, au méthocarbamol et à des soins de soutien suivis de l'anesthésie générale et a été euthanasié. Le bifenthrine, un insecticide de pyréthroide, a été identifié par chromatographie en phase gazeuse et spectométrie de masse du contenu de l'estomac. La toxicité de l'insecticide de pyréthroïde chez le Cochon vietnamien peut donner des signes cliniques semblables à ceux observés chez les animaux de compagnie.(Traduit par Isabelle Vallières).

Feasibility trial of an early therapy in perinatal stroke (eTIPS).

BACKGROUND: Perinatal stroke (PS) affects up to 1/2300 infants and frequently leads to unilateral cerebral palsy (UCP). Preterm-born infants affected by unilateral haemorrhagic parenchymal infarction (HPI) are also at risk of UCP. To date no standardised early therapy approach exists, yet early intervention could be highly effective, by positively influencing processes of activity-dependent plasticity within the developing nervous system including the corticospinal tract. Our aim was to test feasibility and acceptability of an "early Therapy In Perinatal Stroke" (eTIPS) intervention, aiming ultimately to improve motor outcome. METHODS: Design: Feasibility trial, North-East England, August 2015-September 2017. Participants were infants with PS or HPI, their carers and therapists. The intervention consisted of a parent-delivered lateralised therapy approach starting from term equivalent age and continuing until 6 months corrected age. The outcome measures were feasibility (recruitment and retention rates) and acceptability of the intervention (parental questionnaires including the Warwick-Edinburgh Mental Wellbeing Scale (WEBWMS), qualitative observations and in-depth interviews with parents and therapists). We also reviewed clinical imaging data and undertook assessments of motor function, including the Hand Assessment for Infants (HAI). Assessments were also piloted in typically developing (TD) infants, to provide further information on their ease of use and acceptability. RESULTS: Over a period of 18 months we screened 20 infants referred as PS/HPI: 14 met the inclusion criteria and 13 took part. At 6 months, 11 (85%) of those enrolled had completed the final assessment. Parents valued the intervention and found it acceptable and workable. There were no adverse events related to the intervention. We recruited 14 TD infants, one of whom died prior to undertaking any assessments and one of whom was subsequently found to have a condition affecting neurodevelopmental progress: thus, data for 12 TD infants was analysed to 6 months. The HAI was well tolerated by infants and highly valued by parents. Completion rates for the WEBWMS were high and did not suggest any adverse effect of engagement in eTIPS on parental mental wellbeing. CONCLUSION: The eTIPS intervention was feasible to deliver and acceptable to families. We plan to investigate efficacy in a multicentre randomised controlled trial. TRIAL REGISTRATION: ISRCTN12547427 (registration request submitted 28/05/2015; retrospectively registered, 30/09/2015).

Participatory design in the development of an early therapy intervention for perinatal stroke.

BACKGROUND: Perinatal stroke is the leading cause of unilateral (hemiparetic) cerebral palsy, with life-long personal, social and financial consequences. Translational research findings indicate that early therapy intervention has the potential for significant improvements in long-term outcome in terms of motor function. By involving families and health professionals in the development and design stage, we aimed to produce a therapy intervention which they would engage with. METHODS: Nine parents of children with hemiparesis and fourteen health professionals involved in the care of infants with perinatal stroke took part in peer review and focus groups to discuss evolving therapy materials, with revisions made iteratively. The materials and approach were also discussed at a meeting of the London Child Stroke Research Reference Group. Focus group data were coded using Normalisation Process Theory constructs to explore potential barriers and facilitators to routine uptake of the intervention. RESULTS: We developed the Early Therapy in Perinatal Stroke (eTIPS) program - a parent-delivered, home-based complex intervention addressing a current gap in practice for infants in the first 6 months of life after unilateral perinatal stroke and with the aim of improving motor outcome. Parents and health professionals saw the intervention as different from usual practice, and valuable (high coherence). They were keen to engage (high cognitive participation). They considered the tasks for parents to be achievable (high collective action). They demonstrated trust in the approach and felt that parents would undertake the recommended activities (high collective action). They saw the approach as flexible and adaptable (high reflexive monitoring). Following suggestions made, we added a section on involving the extended family, and obtained funding for a website and videos to supplement written materials. CONCLUSIONS: Focus groups with parents and health professionals provided meaningful feedback to iteratively improve the intervention materials prior to embarking on a pilot study. The intervention has a high potential to normalize and become a routine part of parents' interactions with their child following unilateral perinatal stroke.

Assessment and management of the communication difficulties of children with cerebral palsy: a UK survey of SLT practice.

BACKGROUND: Communication difficulties are common in cerebral palsy (CP) and are frequently associated with motor, intellectual and sensory impairments. Speech and language therapy research comprises single-case experimental design and small group studies, limiting evidence-based intervention and possibly exacerbating variation in practice. AIMS: To describe the assessment and intervention practices of speech-language therapist (SLTs) in the UK in their management of communication difficulties associated with CP in childhood. METHODS & PROCEDURES: An online survey of the assessments and interventions employed by UK SLTs working with children and young people with CP was conducted. The survey was publicized via NHS trusts, the Royal College of Speech and Language Therapists (RCSLT) and private practice associations using a variety of social media. The survey was open from 5 December 2011 to 30 January 2012. OUTCOMES & RESULTS: Two hundred and sixty-five UK SLTs who worked with children and young people with CP in England (n = 199), Wales (n = 13), Scotland (n = 36) and Northern Ireland (n = 17) completed the survey. SLTs reported using a wide variety of published, standardized tests, but most commonly reported assessing oromotor function, speech, receptive and expressive language, and communication skills by observation or using assessment schedules they had developed themselves. The most highly prioritized areas for intervention were: dysphagia, alternative and augmentative (AAC)/interaction and receptive language. SLTs reported using a wide variety of techniques to address difficulties in speech, language and communication. Some interventions used have no supporting evidence. Many SLTs felt unable to estimate the hours of therapy per year children and young people with CP and communication disorders received from their service. CONCLUSIONS & IMPLICATIONS: The assessment and management of communication difficulties associated with CP in childhood varies widely in the UK. Lack of standard assessment practices prevents comparisons across time or services. The adoption of a standard set of agreed clinical measures would enable benchmarking of service provision, permit the development of large-scale research studies using routine clinical data and facilitate the identification of potential participants for research studies in the UK. Some interventions provided lack evidence. Recent systematic reviews could guide intervention, but robust evidence is needed in most areas addressed in clinical practice.

Study protocol: longitudinal study of the transition of young people with complex health needs from child to adult health services.

BACKGROUND: Young people with complex health needs have impairments that can limit their ability to carry out day-to-day activities. As well as coping with other developmental transitions, these young people must negotiate the transfer of their clinical care from child to adult services. The process of transition may not be smooth and both health and social outcomes may suffer.Increasingly, policy-makers have recognised the need to ensure a smoother transition between children's and adult services, with processes that are holistic, individualised, and person-centred; however, there is little outcome data to support proposed models of care. This study aims to identify the features of transitional care that are potentially effective and efficient for young people with complex health needs making their transition. METHODS/DESIGN: Longitudinal cohort study. 450 young people aged 14 years to 18 years 11 months (with autism spectrum disorder and an additional mental health problem, cerebral palsy or diabetes) will be followed through their transition from child to adult services and will contribute data at baseline, 12, 24 and 36 months. We will collect data on: health and wellbeing outcomes (participation, quality of life, satisfaction with services, generic health status (EQ-5D-Y) and condition specific measure of disease control or management); exposure to proposed beneficial features of services (such as having a key worker, appropriate involvement of parents); socio-economic characteristics of the sample; use of condition-related health and personal social services; preferences for the characteristics of transitional care.We will us regression techniques to explore how outcomes vary by exposure to service features and by characteristics of the young people. These data will populate a decision-analytic model comparing the costs and benefits of potential alternative ways of organising transition services.In order to better understand mechanisms and aid interpretation, we will undertake qualitative work with 15 young people, including interviews, non-participant observation and diary collection. DISCUSSION: This study will evaluate the effect of service components of transitional care, rather than evaluation of specific models that may be unsustainable or not generalisable. It has been developed in response to numerous national and international calls for such evaluation.

Grappling with uncertainty - Experiences of parents of infants following perinatal stroke.

BACKGROUND: The term perinatal stroke describes focal damage to the developing brain due to cerebrovascular disease and occurring either before or shortly after birth. Aetiology, presentation and evolution differ from stroke in adults. AIMS: We aimed to explore early parental experiences related to having a child with perinatal stroke, including how parental psychological wellbeing had been impacted, to consider how support for families could be improved. METHODS AND PROCEDURES: We undertook a qualitative research study, using in-depth interviews of parents of infants with perinatal stroke when the infants were 5-6 months corrected gestational age. Sixteen parents (11 female, 5 male) of 11 infants with perinatal stroke took part. Thematic analysis was used in data interpretation. OUTCOMES AND RESULTS: Parents described distress related to the lack of information regarding likely outcome following perinatal stroke, as well as confusion around the term 'stroke'. Guilt and self-blame were expressed, with increased emotional sensitivity. Seeking information about stroke to reduce uncertainty was a useful strategy for some, but overwhelming for others. CONCLUSIONS AND IMPLICATIONS: The diagnosis of perinatal stroke led to psychological distress in parents. Uncertainty following diagnosis produced significant emotional difficulties. Recommendations for practice include providing timely, paced information and psychological support.

'Making the most of together time': development of a Health Visitor-led intervention to support children's early language and communication development at the 2-2½-year-old review.

BACKGROUND: Early interventions to support young children's language development through responsive parent-child interaction have proven efficacy but are not currently delivered universally. A potential universal delivery platform is the Health Visitor (HV)-led 2-2½-year-old review in England's Healthy Child Programme. It is unclear if it is feasible to offer such interventions through this platform. We report an intervention development process, including extensive stakeholder consultation and co-design which aimed to develop an acceptable, feasible and equitable early language intervention for delivery in this context. METHODS: The study involved five phases including 13 stakeholder co-design workshops with 7 parents and 39 practitioners (HVs, early years practitioners and speech and language therapists): (1) Identification of existing intervention evidence, (2) qualitative review of intervention studies extracting candidate target behaviours for intervention and intervention techniques, (3) co-design workshops with parents and practitioners examining acceptability, barriers and enablers to those behaviours and techniques (particular attention was paid to diverse family circumstances and the range of barriers which might exist), (4) findings were analysed using COM-B and theoretical domains frameworks and a prototype intervention model designed, and (5) co-design workshops iteratively refined the proposed model. RESULTS: Practitioners were committed to offering language intervention at the 2-2½-year-old review but were not sure precisely how to do so. Parents/caregivers wanted to be proactive and to have agency in supporting their own children and to do this as soon as possible. For equitable intervention, it must be proportionate, with higher 'intensity' for higher levels of disadvantage, and tailored, offering differing approaches considering the specific barriers and enablers, assets and challenges in each family. The importance and potential fragility of alliances between parent/caregiver and practitioner were identified as key, and so, strategies to engender successful collaborative partnership are also embedded in intervention design. CONCLUSION: It is possible to develop a universal intervention which parents and practitioners judge would be acceptable, feasible and equitable for use at the 2-2½-year review to promote children's language development. The result is one of the most explicitly developed universal interventions to promote children's language development. Further development and piloting is required to develop materials to support successful widespread implementation.

Inclusion of person-centred care in medical and nursing undergraduate curricula in the UK: Interviews and documentary analysis.

OBJECTIVE: We aimed to understand how person-centred care (PCC) is represented in UK professional standards for undergraduate medical/nursing education and explored how these are reflected in programme provision. METHODS: We identified PCC components in medical (GMC) and nursing (NMC) professional standards and university curricula documents provided. We also identified themes from interviews with high-level informants for medical/nursing undergraduate programmes using framework analysis. RESULTS: The GMC appears to promote a more paternalistic model of care with discrete PCC components in specific sections and the NMC a more collaborative model with PCC distributed throughout. These differences persisted into education delivery. Medical educators perceived greater barriers to inclusion of PCC than nursing educators; however, both consistently identified cultural and organisational attributes. Clarity was lacking regarding PCC definition, how to teach/assess PCC, and competence expectations. CONCLUSION: Development of a PCC skills competence framework would increase consistency and support teaching and assessment in undergraduate curricula. Further research to understand the perspectives of healthcare professionals involved in placements would help inform PCC teaching recommendations. PRACTICE IMPLICATIONS: High-level support from senior HEI leaders; multi-disciplinary approaches to curricula development, teaching, and assessment; and greater inclusion of service users would ensure higher quality PCC education for undergraduate students.

Rab5 and Rab7 control endocytic sorting along the axonal retrograde transport pathway.

Vesicular pathways coupling the neuromuscular junction with the motor neuron soma are essential for neuronal function and survival. To characterize the organelles responsible for this long-distance crosstalk, we developed a purification strategy based on a fragment of tetanus neurotoxin (TeNT H(C)) conjugated to paramagnetic beads. This approach enabled us to identify, among other factors, the small GTPase Rab7 as a functional marker of a specific pool of axonal retrograde carriers, which transport neurotrophins and their receptors. Furthermore, Rab5 is essential for an early step in TeNT H(C) sorting but is absent from axonally transported vesicles. Our data demonstrate that TeNT H(C) uses a retrograde transport pathway shared with p75(NTR), TrkB, and BDNF, which is strictly dependent on the activities of both Rab5 and Rab7. Therefore, Rab7 plays an essential role in axonal retrograde transport by controlling a vesicular compartment implicated in neurotrophin traffic.

Spatially distinct binding of Cdc42 to PAK1 and N-WASP in breast carcinoma cells.

While a significant amount is known about the biochemical signaling pathways of the Rho family GTPase Cdc42, a better understanding of how these signaling networks are coordinated in cells is required. In particular, the predominant subcellular sites where GTP-bound Cdc42 binds to its effectors, such as p21-activated kinase 1 (PAK1) and N-WASP, a homolog of the Wiskott-Aldritch syndrome protein, are still undetermined. Recent fluorescence resonance energy transfer (FRET) imaging experiments using activity biosensors show inconsistencies between the site of local activity of PAK1 or N-WASP and the formation of specific membrane protrusion structures in the cell periphery. The data presented here demonstrate the localization of interactions by using multiphoton time-domain fluorescence lifetime imaging microscopy (FLIM). Our data here establish that activated Cdc42 interacts with PAK1 in a nucleotide-dependent manner in the cell periphery, leading to Thr-423 phosphorylation of PAK1, particularly along the lengths of cell protrusion structures. In contrast, the majority of GFP-N-WASP undergoing FRET with Cy3-Cdc42 is localized within a transferrin receptor- and Rab11-positive endosomal compartment in breast carcinoma cells. These data reveal for the first time distinct spatial association patterns between Cdc42 and its key effector proteins controlling cytoskeletal remodeling.

General practitioners and emergency departments (GPED)-efficient models of care: a mixed-methods study protocol.

INTRODUCTION: Pressure continues to grow on emergency departments in the UK and throughout the world, with declining performance and adverse effects on patient outcome, safety and experience. One proposed solution is to locate general practitioners to work in or alongside the emergency department (GPED). Several GPED models have been introduced, however, evidence of effectiveness is weak. This study aims to evaluate the impact of GPED on patient care, the primary care and acute hospital team and the wider urgent care system. METHODS AND ANALYSIS: The study will be divided into three work packages (WPs). WP-A; Mapping and Taxonomy: mapping, description and classification of current models of GPED in all emergency departments in England and interviews with key informants to examine the hypotheses that underpin GPED. WP-B; Quantitative Analysis of National Data: measurement of the effectiveness, costs and consequences of the GPED models identified in WP-A, compared with a no-GPED model, using retrospective analysis of Hospital Episode Statistics Data. WP-C; Case Studies: detailed case studies of different GPED models using a mixture of qualitative and quantitative methods including: non-participant observation of clinical care, semistructured interviews with staff, patients and carers; workforce surveys with emergency department staff and analysis of available local routinely collected hospital data. Prospective case study sites will be identified by completing telephone interviews with sites awarded capital funding by the UK government to implement GPED initiatives. The study has a strong patient and public involvement group that has contributed to study design and materials, and which will be closely involved in data interpretation and dissemination. ETHICS AND DISSEMINATION: The study has been approved by the National Health Service East Midlands-Leicester South Research Ethics Committee: 17/EM/0312. The results of the study will be disseminated through peer-reviewed journals, conferences and a planned programme of knowledge mobilisation. TRIAL REGISTRATION NUMBER: ISRCTN51780222.

In vitro reconstitution of fusion between immature autophagosomes and endosomes.

Autophagy is a highly conserved degradative pathway whereby a double membrane engulfs cytoplasmic constituents to form an autophagic vacuole or autophagosome. An essential requirement for efficient autophagy is the acquisition of an adequate degradative capacity by the autophagosomes. To acquire this capacity the immature autophagic vacuoles (AVis) obtain lysosomal hydrolases by fusion with endosomes. The current models suggest that at least two types of endosomes, early and late, fuse with AVis to form mature, degradative AVds. This fusion and maturation requires proteins also involved in endosome maturation such as Rab7. However, it is not known if there are molecular requirements unique to AVi-endosome fusion. To identify and investigate the molecular requirements of this fusion we developed a cell-free fusion assay based on content mixing, which occurs after fusion of isolated AVis and different endosomal fractions. Our assay shows that isolated AVis can fuse to a similar extent in vitro with both early and late endosomes. Furthermore, fusion between autophagosomes and endosomes requires cytosolic and endosomal proteins, but does not show a nucleotide-dependence, and is partially N-ethylmaleimide sensitive. We also demonstrate that the lipidated form of the autophagosomal protein LC3 is dispensable for this fusion event.

The dystonia-associated protein torsinA modulates synaptic vesicle recycling.

The loss of a glutamic acid residue in the AAA-ATPase (ATPases associated with diverse cellular activities) torsinA is responsible for most cases of early onset autosomal dominant primary dystonia. In this study, we found that snapin, which binds SNAP-25 (synaptosome-associated protein of 25,000 Da) and enhances the association of the SNARE complex with synaptotagmin, is an interacting partner for both wild type and mutant torsinA. Snapin co-localized with endogenous torsinA on dense core granules in PC12 cells and was recruited to perinuclear inclusions containing mutant DeltaE-torsinA in neuroblastoma SH-SY5Y cells. In view of these observations, synaptic vesicle recycling was analyzed using the lipophilic dye FM1-43 and an antibody directed against an intravesicular epitope of synaptotagmin I. We found that overexpression of wild type torsinA negatively affects synaptic vesicle endocytosis. Conversely, overexpression of DeltaE-torsinA in neuroblastoma cells increases FM1-43 uptake. Knockdown of snapin and/or torsinA using small interfering RNAs had a similar inhibitory effect on the exo-endocytic process. In addition, down-regulation of torsinA causes the persistence of synaptotagmin I on the plasma membrane, which closely resembles the effect observed by the overexpression of the DeltaE-torsinA mutant. Altogether, these findings suggest that torsinA plays a role together with snapin in regulated exocytosis and that DeltaE-torsinA exerts its pathological effects through a loss of function mechanism. This may affect neuronal uptake of neurotransmitters, such as dopamine, playing a role in the development of dystonic movements.

GGA function is required for maturation of neuroendocrine secretory granules.

Secretory granule (SG) maturation has been proposed to involve formation of clathrin-coated vesicles (CCVs) from immature SGs (ISGs). We tested the effect of inhibiting CCV budding by using the clathrin adaptor GGA (Golgi-associated, gamma-ear-containing, ADP-ribosylation factor-binding protein) on SG maturation in neuroendocrine cells. Overexpression of a truncated, GFP-tagged GGA, VHS (Vps27, Hrs, Stam)-GAT (GGA and target of myb (TOM))-GFP led to retention of MPR, VAMP4, and syntaxin 6 in mature SGs (MSGs), suggesting that CCV budding from ISGs is inhibited by the SG-localizing VHS-GAT-GFP. Furthermore, VHS-GAT-GFP-overexpression disrupts prohormone convertase 2 (PC2) autocatalytic cleavage, processing of secretogranin II to its product p18, and the correlation between PC2 and p18 levels. All these effects were not observed if full-length GGA1-GFP was overexpressed. Neither GGA1-GFP nor VHS-GAT-GFP perturbed SG protein budding from the TGN, or homotypic fusion of ISGs. Reducing GGA3 levels by using short interfering (si)RNA also led to VAMP4 retention in SGs, and inhibition of PC2 activity. Our results suggest that inhibition of CCV budding from ISGs downregulates the sorting from the ISGs and perturbs the intragranular activity of PC2.

PKC epsilon controls the traffic of beta1 integrins in motile cells.

Protein kinase C (PKC) has been implicated in beta 1 integrin-mediated cell migration. Expression of the novel PKC isoform, PKC epsilon, in PKC epsilon(-/-) cells is shown here to stimulate directional migration of cells towards beta 1 integrin substrates in a manner dependent on PKC catalytic activity. On PKC inhibition, integrin beta 1 and PKC epsilon become reversibly trapped in a tetraspanin (CD81)-positive intracellular compartment, correlating with reduced haptotaxis. Immunofluorescence and pulse labelling studies indicate that this is a previously uncharacterized recycling compartment trapped by inhibition of PKC. Electron microscopy demonstrated the co-localization of PKC epsilon and integrin beta 1 on the vesicular membranes. Finally, using a reconstituted in vitro system, the dissociation of PKC epsilon from these vesicles is shown to be dependent on both the presence of cytosolic components and energy, and on PKC catalytic activity. The evidence presented indicates that PKC epsilon controls an internal traffic step that under uninhibited conditions permits the recycling of beta 1 integrin, contributing to cell motility.

Spatially restricted patterning cues provided by heparin-binding VEGF-A control blood vessel branching morphogenesis.

Branching morphogenesis in the mammalian lung and Drosophila trachea relies on the precise localization of secreted modulators of epithelial growth to select branch sites and direct branch elongation, but the intercellular signals that control blood vessel branching have not been previously identified. We found that VEGF(120/120) mouse embryos, engineered to express solely an isoform of VEGF-A that lacks heparin-binding, and therefore extracellular matrix interaction domains, exhibited a specific decrease in capillary branch formation. This defect was not caused by isoform-specific differences in stimulating endothelial cell proliferation or by impaired isoform-specific signaling through the Nrp1 receptor. Rather, changes in the extracellular localization of VEGF-A in heparin-binding mutant embryos resulted in an altered distribution of endothelial cells within the growing vasculature. Instead of being recruited into additional branches, nascent endothelial cells were preferentially integrated within existing vessels to increase lumen caliber. The disruption of the normal VEGF-A concentration gradient also impaired the directed extension of endothelial cell filopodia, suggesting that heparin-binding VEGF-A isoforms normally provide spatially restricted stimulatory cues that polarize and thereby guide sprouting endothelial cells to initiate vascular branch formation. Consistent with this idea, we found opposing defects in embryos harboring only a heparin-binding isoform of VEGF-A, including excess endothelial filopodia and abnormally thin vessel branches in ectopic sites. We conclude that differential VEGF-A isoform localization in the extracellular space provides a control point for regulating vascular branching pattern.