http://experimentationlab.berkeley.edu/sites/default/files/AFMImages/butt_AFM.pdf

Force measurements with the atomic force microscope: Technique, interpretation and applications

Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the con- centration of an inhibitor such as Colcemid. Fibroblasts of high population doubling level propagated in vitro, which have left the cell cycle, can carry out the contraction at least as efficiently as cycling cells. The potential uses of the system as an immu- nologically tolerated "tissue" for wound hea ing and as a model for studying fibroblast function are discussed.

Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative

Medicine has evolved from the undertaking of the individual practitioner to a state in which many disciplines become involved in administering both diagnostic and treatment services. It has become a standard of care in hospital and clinic-based practice to utilize a multidisciplinary approach to medical care. Multidisciplinary modes of practice, however, do not ensure that participants interact cooperatively, or with the exclusive purpose of patient benefit. The usual mode of interaction within medical academic and clinical environments promotes individualism, protectionism, and some degree of isolation, not infrequently to the detriment of patient care. The stated purpose of this book is to provide a synthesis of theories and methodologies that promote a growing permeability of boundaries and that allow for intellectual accommodation. Health care professionals have been turning to interdisciplinary intervention approaches for several reasons, but the most compelling in medicine is the need to solve problems that are beyond the

Interdisciplinarity: History, Theory, and Practice

Second, communication within the audience segments is repeatedly acknowledged as the basis of transformation of labeled sets into classes, types into categories, and concepts into forms. One needs to clarify this communication process, describe it, and understand it. Prior ecological works presumed that the classification task was incumbent to the observer, raising questions about the validity, existence, and durability of the categories and forms (e.g., Durand 2006). Undoubtedly, the formalization of diverse audiences’ comparative categorization proposed in the book represents a major reconceptualization, but the societal hierarchies, verticalities, and conflicts need to be part of the communication basis. Third, although the fourth part of the book deals with organizational change, loyal to the core assumptions of ecology theory, the organizations and their spokespersons do not seem able to influence the evolution of the fields, industries, or populations. Organizations hardly possess intentions, governance characteristics, or market and non-market resources to do better than adapt a multimeaning multi-audience reality, to wit to shape, carve, and influence the very selection criteria that rule the fields where they operate. Finally, more than the possibility of categorization, the ontological nature of forms and population is a question looming around the entire population ecology story, old and new style. Yesterday imposed by the ecologist as erudite observer, today forms and populations are “decentralized” to audiences. This displacement fills a caveat of the former version of population ecology. The next question worth investigation nevertheless lies in the epistemological nature and ontological status of concepts, categories, forms, and populations. Does the linguistic turn of organizational ecology open the Pandora’s box for a neo-constructivism, a post-realism about forms and populations? Organizational ecologists have long avoided the too-human considerations of politics and ideologies. However, the decentralization of categorization processes, the evanescence of group membership, and the importance given to (social and cultural) codes imply that beliefs, causal associations, and discursive elaboration are to integrate the newly refounded ecological corpus. Overall, I applaud the conceptual details, thorough definitions, and meticulous demonstrations of this book. Readers of the book will appreciate differently this new theorization of known themes, from full acceptance to some resistance. One may regret certain minimal or backhanded references to extant literature (in particular on social categorization, status construction, and organizational identity). One may reject premises (having a more political theory of legitimacy, a more controversial social positioning of audiences, and a more classificatory argument of audiences’ habitus). But everyone can make up their mind by reading and appreciating the conceptual qualities of this book.

Rethinking ExpertiseRethinking Expertise, by CollinsHarry and EvansRobert. Chicago, IL: The University of Chicago Press, 2007. 159 pp. $37.50 cloth. 0226113604.

Transforming Growth Factor-β1 (TGF-β1)-stimulated Fibroblast to Myofibroblast Differentiation Is Mediated by Hyaluronan (HA)-facilitated Epidermal Growth Factor Receptor (EGFR) and CD44 Co-localization in Lipid Rafts

To overcome the difficulties of studying wounding and wound repopulation in monolayer systems, a 3-dimensional model of wound repopulation has been developed which allows the in vitro investigation of fibroblast migration in response to experimental wounding. This model was utilized to determine whether fibroblasts derived from sites which demonstrate preferential healing (child and oral mucosal fibroblasts) possessed an increased ability to repopulate experimental wounds when compared to adult dermal fibroblasts. Fibroblasts were established from specimens derived from healthy donors undergoing minor elective surgery. Standard wounds were created in fibroblast populated collagen lattices (FPCLs) which were then overlaid upon an extracellular wound matrix. Fibroblast repopulation of the wounds was studied over 12 days using light- and scanning electron microscopy and quantified using computerized image analysis. Wound repopulation by fibroblasts derived from child donors (n = 3) was significantly (P < 0.0...

An investigation of preferential fibroblast wound repopulation using a novel in vitro wound model

Simplified in vitro models such as cellular monolayer cultures have only limited usefulness in the study of cutaneous wound repair processes. This has stimulated the investigation of three-dimensional tissue equivalent systems such as the dermal and skin equivalent models. With the use of a wound system constructed of rat tail type I collagen and human dermal fibroblasts, experimental wounding was accompanied by problems with mechanical scoring of the plastic substratum which prevented cell migration. These problems were overcome with the use of a multilayered model in which a punch biopsy-wounded dermal equivalent (bilayered model) or skin equivalent (tri-layered model) was placed onto an acellular collagen lattice and fixed in place with polymerizing collagen. This model permitted observation of the process of cellular repopulation of the "wound space," into which both fibroblast and keratinocyte migration commenced within 1 day. The number of fibroblasts in this space increased dramatically over a period of 9 days, the cells appearing to migrate both over and through the acellular lower collagen layer. Keratinocyte reepithelialization of the "wound space" was completed after 5 days. With the model it was shown that platelet-derived growth factor--AB and epidermal growth factor had positive effects in increasing fibroblast number within the wound space. In conclusion, the model described here should facilitate the study of fibroblast and keratinocyte responses to a wound stimulus in vitro and be a plausible in vitro system for evaluating agents which may have a potential stimulatory or inhibitory effect on numerous cellular responses associated with wound healing.

Development of a multilayered in vitro model for studying events associated with wound healing.

Background Small extracellular vesicles (SEVs) have a diameter between 30 and 150 nm and play a key role in cell‐cell communication. As cells cultured in 3D vs 2D behave differently, this project aimed to assess whether there were differences in SEVs derived from human oral mucosa lamina propria‐progenitor cells (OMLP‐PCs) cultured in a 3D matrix compared with traditional 2D monolayer cultures. Methods OMLP‐PCs were cultured in 3D type I collagen matrices or on traditional 2D tissue culture plastic. Cell morphology and viability were assessed by light microscopy, actin staining, and trypan blue staining. SEVs secreted by OMLP‐PCs were purified and quantitatively analyzed by a BCA assay and nanoparticle tracking analysis (NTA; nanosight™). SEVs were further characterized by flow cytometry. SEV proliferative function was assessed by a 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. Results Cells cultured in 3D grew well as observed by light microscopy and phalloidin staining with cells branching in three dimensions (as opposed to the cells grown as monolayers on tissue culture plastic). NTA demonstrated a significantly higher number of SEV‐sized particles in the conditioned medium of cells grown in 3D type I collagen matrices vs a 2D monolayer (P < .01). Like SEVs from 2D culture, SEVs from 3D culture demonstrated a particle size within the expected SEV range. Tetraspanin analysis confirmed that 3D‐derived SEVs were positive for typical, expected tetraspanins. Cell proliferation analysis demonstrated that SEVs produced through 3D cell culture conditions significantly reduced the proliferation of skin fibroblasts when compared with SEVs from 2D monolayers (P < .05). Conclusion 3D culture of OMLP‐PCs produced typical SEVs but in a greater amount than when the same cells were cultured in 2D. The downstream proliferative potential of the SEVs was influenced by the initial culture methodology. Future work should now assess the potential effects of 3D SEVs on key wound healing activities.

/pdf/three-dimensional-culture-of-oral-progenitor-cells-effects-3jq9etmylv.pdf

Three-dimensional culture of oral progenitor cells: Effects on small extracellular vesicles production and proliferative function.

An engineering approach to the development of biomaterials for promotion of wound healing emphasises the im- portance of a well-controlled architecture and concentrates on optimisation of morphology and surface chemistry to stimulate guidance of the cells within the wound environment. A series of three-dimensional porous scaffolds with 80-90% bulk porosity and fully interconnected macropores were prepared from two biodegradable materials - cellulose acetate (CA) and poly (lactic- co-glycolic acid) (PLGA) through the phase inversion mechanism of formation. Surface morphology of obtained scaffolds was determined using atomic force microscopy (AFM) in conjunction with optical microscopy. Scanning Electron Microscopy (SEM) was applied to characterise scaffolds bulk morphology. Biocompatibility and biofunctionality of the prepared materials were assessed through a systematic study of cell/material interactions using atomic force microscopy (AFM) methodologies to- gether with in vitro cellular assays. Preliminary data with human fibroblasts demonstrated a positive influence of both scaffolds on cellular attachment and growth. The adhesion of cells on both biomaterials were quantified by AFM force measurements in conjunction with a cell probe technique since, for the first time, a fibroblast probe has been successfully developed and optimal conditions of immobilisation of the cells on the AFM cantilever have been experimentally determined.

/pdf/development-and-afm-study-of-porous-scaffolds-for-wound-2tz5zawzy6.pdf

Development and AFM study of porous scaffolds for wound healing applications

We report an analysis of how an interdisciplinary project bringing together biologists, physicists and engineers worked in practice. The authorship team are the Principle Investigator who led the project, and a social scientist who studied the project as it was conducted by interviewing participants and observing practice. We argue it is accurate and productive to think of the interdisciplinary team as an Expert-Network, which means it was a managed set of relationships between disciplinary groups punctuated by specific junctions at which interdisciplinary exchange of materials, knowledge, and in limited cases, practices, occurred. We stress the role of trust in knowledge exchange, and document how hard sharing knowledge – and especially tacit knowledge - between disciplines can be. Key is the flexible management of the network, as the membership and required skill set change. Our analysis is embedded within, and contributes to, the Sociology of Experience and Expertise (SEE) framework. We close by suggesting advice for others seeking to manage a similar interdisciplinary Expert-Network.

/pdf/interdisciplinary-projects-as-an-expert-network-analysing-2n8g3uy4qk.pdf

Phil Stephens

Papers

An investigation of preferential fibroblast wound repopulation using a novel in vitro wound model

Development of a multilayered in vitro model for studying events associated with wound healing.

Three-dimensional culture of oral progenitor cells: Effects on small extracellular vesicles production and proliferative function.

Development and AFM study of porous scaffolds for wound healing applications

Interdisciplinary Projects as an Expert-Network: Analysing Team Work Across Biological and Physical Sciences