TGFβ carrying exosomes in plasma: potential biomarkers of cancer progression in patients with head and neck squamous cell carcinoma

OBJECTIVES

Contributions of TGFβ to cancer progression are well documented. However, plasma TGFβ levels often do not correlate with clinicopathological data. We examine the role of TGFβ carried in exosomes isolated from murine and human plasma as a contributor to disease progression in head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

The 4-nitroquinoline-1-oxide (4-NQO) mouse model was used to study changes in TGFβ expression levels during oral carcinogenesis. In human HNSCC, TGFβ and Smad3 protein expression levels and TGFB1 gene expression were determined. Soluble TGFβ levels were evaluated by ELISA and TGFβ bioassays. Exosomes were isolated from plasma using size exclusion chromatography, and TGFβ content was quantified using bioassays and bioprinted microarrays.

RESULTS

During 4-NQO carcinogenesis, TGFβ levels in tumour tissues and in serum increased as the tumour progressed. The TGFβ content of circulating exosomes also increased. In HNSCC patients, TGFβ, Smad3 and TGFB1 were overexpressed in tumour tissues and correlated with increased soluble TGFβ levels. Neither TGFβ expression in tumours nor levels of soluble TGFβ correlated with clinicopathological data or survival. Only exosome-associated TGFβ reflected tumour progression and correlated with tumour size.

CONCLUSIONS

Circulating TGFβ+ exosomes in the plasma of patients with HNSCC emerge as potential non-invasive biomarkers of disease progression in HNSCC.

Protocol to engineer apical-out airway organoids using suspension culture of human airway basal stem cell aggregates

Here we present a protocol to engineer apical-out airway organoids (AOAOs) directly from human airway basal stem cells (hABSCs) using suspension culture of hABSC aggregates on a cell-repellent surface. We describe steps to produce spherical AOAOs with homogenous presentation of exterior-facing motile cilia and of tunable sizes. We then detail procedures to analyze AOAO cellular composition via wholemount staining and assess cilia motility via 3D AOAO rotation upon Matrigel embedding. The protocol offers an effective model for investigating human airway pathophysiology. For complete details on the use and execution of this protocol, please refer to Wijesekara et al. (2022).¹.

Skin-targeted delivery of extracellular vesicle-encapsulated curcumin using dissolvable microneedle arrays

Therapeutic benefits of curcumin for inflammatory diseases have been demonstrated. However, curcumin's potential as a clinical therapeutic has been hindered due to its low solubility and stability in vivo. We hypothesized that a hybrid curcumin carrier that incorporates albumin-binding and extracellular vesicle (EV) encapsulation could effectively address the current challenges of curcumin delivery. We further postulated that using dissolvable microneedle arrays (dMNAs) for local delivery of curcumin-albumin-EVs (CA-EVs) could effectively control skin inflammation in vivo. Mild sonication was used to encapsulate curcumin and albumin into EVs, and the resulting CA-EVs were integrated into tip-loaded dMNAs. In vitro and in vivo studies were performed to assess the stability, cellular uptake, and anti-inflammatory bioactivity of dMNA-delivered CA-EVs. Curcumin in CA-EVs exhibited at least five-fold higher stability in vitro than naïve curcumin or curcumin-EVs without albumin. Incorporating CA-EVs into dMNAs did not alter their cellular uptake or anti-inflammatory bioactivity. The dMNA embedded CA-EVs retained their bioactivity when stored at room temperature for at least 12 months. In rat and mice models, dMNA delivered CA-EVs suppressed and significantly reduced lipopolysaccharide and Imiquimod-triggered inflammation. We conclude that dMNA delivery of CA-EVs has the potential to become an effective local-delivery strategy for inflammatory skin diseases. STATEMENT OF SIGNIFICANCE: We introduce and evaluate a skin-targeted delivery system for curcumin that synergistically combines albumin association, extracellular-vesicle encapsulation, and dissolvable microneedle arrays (dMNAs) . In vitro, curcumin-albumin encapsulated extracellular vesicles (CA-EVs) inhibit and reverse the LPS-triggered expression of inflammatory transcription factor NF-κB. The integration of CA-EVs into dMNAs does not affect them physically or functionally. Importantly, dMNAs extend EV storage stability for at least 12 months at room temperature with minimal loss in their bioactivity. We demonstrate that dMNA delivered CA-EVs effectively block and reverse skin inflammation in vivo in mouse and rat models.

Controlled Release of Exosomes Using Atom Transfer Radical Polymerization-Based Hydrogels

Exosomes are 30-200 nm sized extracellular vesicles that are increasingly recognized as potential drug delivery vehicles. However, exogenous exosomes are rapidly cleared from the blood upon intravenous delivery, which limits their therapeutic potential. Here, we report bioactive exosome-tethered poly(ethylene oxide)-based hydrogels for the localized delivery of therapeutic exosomes. Using cholesterol-modified DNA tethers, the lipid membrane of exosomes was functionalized with initiators to graft polymers in the presence of additional initiators and crosslinker using photoinduced atom transfer radical polymerization (ATRP). This strategy of tethering exosomes within the hydrogel network allowed their controlled release over a period of 1 month, which was much longer than physically entrapped exosomes. Exosome release profile was tuned by varying the crosslinking density of the polymer network and the use of photocleavable tethers allowed stimuli-responsive release of exosomes. The therapeutic potential of the hydrogels was assessed by evaluating the osteogenic potential of bone morphogenetic protein 2-loaded exosomes on C2C12 and MC3T3-E1 cells. Thus, ATRP-based exosome-tethered hydrogels represent a tunable platform with improved efficacy and an extended-release profile.

Radioiodination of extravesicular surface constituents to study the biocorona, cell trafficking and storage stability of extracellular vesicles

BACKGROUND

Extracellular vesicles (EVs) are produced by all cell types and serve as biological packets delivering a wide variety of molecules for cell-to-cell communication. However, the biology of the EV extravesicular surface domain that we have termed EV 'biocorona' remains underexplored. Upon cell secretion, EVs possess an innate biocorona containing membrane integral and peripheral constituents that is modified by acquired constituents post secretion. This distinguishes EVs from synthetic nanoparticulate biomaterials that are limited to an adsorption-based, acquired biocorona.

METHODS

The EV biocorona molecular constituents were radiolabeled with 125I to study biocorona constituents and its surface dynamics. As example toolset applications, 125I-EVs were utilized to study EV cell trafficking and the stability of the EV biocorona during storage.

RESULTS

The biocorona of EVs consisted of proteins, lipids, DNA and RNA. The cellular uptake of 125I-EVs was temperature dependent and internalized 125I-EVs were rapidly recycled by cells. When 125I-EVs were stored in a purified state, they exhibited time and temperature dependent biocorona shedding and proteolytic degradation that was partially inhibited in the presence of serum.

CONCLUSION

The EV biocorona is complex and dynamic. Radiolabeling of the EV biocorona enables a unique platform methodology to study the biocorona and will facilitate unlocking EV's full clinical translation potential.

GENERAL SIGNIFICANCE

The EV biocorona affects EV mediated biological processes in health and disease. Acquiring knowledge of the EV biocorona composition, dynamics, stability and structure not only informs the diagnostic and therapeutic translation of EVs but also aids in designing biomimetic nanomaterials for drug delivery.

Cell trafficking and regulation of osteoblastogenesis by extracellular vesicle associated bone morphogenetic protein 2

Extracellular vesicles (EVs) are characterized by complex cargo composition and carry a wide array of signalling cargo, including growth factors (GFs). Beyond surface-associated GFs, it is unclear if EV intralumenal growth factors are biologically active. Here, bone morphogenetic protein-2 (BMP2), loaded directly into the lumen of EVs designated engineered BMP2-EVs (eBMP2-EVs), was comprehensively characterized including its regulation of osteoblastogenesis. eBMP2-EVs and non-EV 'free' BMP2 were observed to similarly regulate osteoblastogenesis. Furthermore, cell trafficking experiments suggest rapid BMP2 recycling and its extracellular release as 'free' BMP2 and natural occurring BMP2-EVs (nBMP2-EVs), with both being osteogenic. Interestingly, BMP2 occurs on the EV surface of nBMP2-EVs and is susceptible to proteolysis, inhibition by noggin and complete dissociation from nBMP2-EVs over 3 days. Whereas, within the eBMP2-EVs, BMP2 is protected from proteolysis, inhibition by noggin and is retained in EV lumen at 100% for the first 24 h and ∼80% after 10 days. Similar to 'free' BMP2, bioprinted eBMP2-EV microenvironments induced osteogenesis in vitro and in vivo in spatial registration to the printed patterns. Taken together, BMP2 signalling involves dynamic BMP2 cell trafficking in and out of the cell involving EVs, with distinct differences between these nBMP2-EVs and eBMP2-EVs attributable to the BMP2 cargo location with EVs. Lastly, eBMP2-EVs appear to deliver BMP2 directly into the cytoplasm, initiating BMP2 signalling within the cell, bypassing its cell surface receptors.

Engineering exosome polymer hybrids by atom transfer radical polymerization

Exosomes are emerging as ideal drug delivery vehicles due to their biological origin and ability to transfer cargo between cells. However, rapid clearance of exogenous exosomes from the circulation as well as aggregation of exosomes and shedding of surface proteins during storage limit their clinical translation. Here, we demonstrate highly controlled and reversible functionalization of exosome surfaces with well-defined polymers that modulate the exosome's physiochemical and pharmacokinetic properties. Using cholesterol-modified DNA tethers and complementary DNA block copolymers, exosome surfaces were engineered with different biocompatible polymers. Additionally, polymers were directly grafted from the exosome surface using biocompatible photo-mediated atom transfer radical polymerization (ATRP). These exosome polymer hybrids (EPHs) exhibited enhanced stability under various storage conditions and in the presence of proteolytic enzymes. Tuning of the polymer length and surface loading allowed precise control over exosome surface interactions, cellular uptake, and preserved bioactivity. EPHs show fourfold higher blood circulation time without altering tissue distribution profiles. Our results highlight the potential of precise nanoengineering of exosomes toward developing advanced drug and therapeutic delivery systems using modern ATRP methods.

Bacterial Extracellular Vesicle Mediated Host-Pathogen Interactions in Pneumococcal Infections

Extracellular vesicles (EVs) represent a highly sophisticated cell-to-cell mailing system across all biological kingdoms. EVs have long been characterized from many Gram-negative species and, recently from Gram-positive bacteria, including the major respiratory pathogen Streptococcus pneumoniae (pneumococcus).

Our studies reveal that pneumococcal-derived vesicles can be internalized by macrophages, T cells, and epithelial cells. In vitro, EVs induce cytokine signaling in macrophages, including dose-dependent NF-kB signaling in murine RAW 264.7 and human primary macrophages. When administered systemically into a mouse, pneumococcal EVs result in splenomegaly and induced a sepsis-like cytokine storm. When immobilized in a hydrogel implant for local administration into a mouse, pneumococcal EVs recruited lymphocytes and macrophages. Moreover, pneumococcal lipoproteins are major contributors to NF-kB signaling and inflammatory responses, as these phenotypes were substantially reduced with EVs from a lipoprotein deficient strain (Δlgt) as compared to EVs from the wildtype strain. Taken together, in vivo studies suggest that pneumococcal vesicles alone are sufficient to induce inflammatory responses and tissue damage in mammalian hosts.

Overall, our data suggest that pneumococcal EVs display potent immunomodulatory effects on host immune cells highlighting their pivotal role during the infectious process, either by manipulating host responses or by triggering host-defense systems. Thus, pneumococcal EVs are virulence determinants and may be effective tools for vaccine development.

Rapid On-Demand Extracellular Vesicle Augmentation with Versatile Oligonucleotide Tethers

Exosomes show potential as ideal vehicles for drug delivery because of their natural role in transferring biological cargo between cells. However, current methods to engineer exosomes without negatively impacting their function remain challenging. Manipulating exosome-secreting cells is complex and time-consuming, while direct functionalization of exosome surface proteins suffers from low specificity and low efficiency. We demonstrate a rapid, versatile, and scalable method with oligonucleotide tethers to enable diverse surface functionalization on both human and murine exosomes. These exosome surface modifiers, which range from reactive functional groups and small molecules to aptamers and large proteins, can readily and efficiently enhance native exosome properties. We show that cellular uptake of exosomes can be specifically altered with a tethered AS1411 aptamer, and targeting specificity can be altered with a tethered protein. We functionalize exosomes with an immunomodulatory protein, FasL, and demonstrate their biological activity both in vitro and in vivo. FasL-functionalized exosomes, when bioprinted on a collagen matrix, allows spatial induction of apoptosis in tumor cells and, when injected in mice, suppresses proliferation of alloreactive T cells. This oligonucleotide tethering strategy is independent of the exosome source and further circumvents the need to genetically modify exosome-secreting cells.

Covalent Poly(lactic acid) Nanoparticles for the Sustained Delivery of Naloxone

The opioid epidemic currently plaguing the United States has been exacerbated by an alarming rise in fatal overdoses as a result of the proliferated abuse of synthetic mu opioid receptor (MOR) agonists, such as fentanyl and its related analogues. Attempts to manage this crisis have focused primarily on widespread distribution of the clinically approved opioid reversal agent naloxone (Narcan); however, due to the intrinsic metabolic lability of naloxone, these measures have demonstrated limited effectiveness against synthetic opioid toxicity. This work reports a novel polymer-based strategy to create a long-acting formulation of naloxone with the potential to address this critical issue by utilizing covalent nanoparticle (cNP) drug delivery technology. Covalently loaded naloxone nanoparticles (Nal-cNPs) were prepared via the naloxone-initiated, ring-opening polymerization (ROP) of l-lactide in the presence of a bifunctional thiourea organocatalyst with subsequent precipitation of the resulting naloxone-poly(l-lactic acid) polymer. This protocol afforded well-defined nanoparticles possessing a drug loading of approximately 7% w/w. The resulting Nal-cNPs demonstrated excellent biocompatibility, while exhibiting sustained linear release kinetics in vitro and blocking the effects of high dose (10 mg/kg) acute morphine for up to 98 h in an in vivo rodent model of neuropathic pain.

Plasma-based biomaterials for the treatment of cutaneous radiation injury

Cutaneous wounds caused by an exposure to high doses of ionizing radiation remain a therapeutic challenge. While new experimental strategies for treatment are being developed, there are currently no off‐the‐shelf therapies for the treatment of cutaneous radiation injury that have been proven to promote repair of the damaged tissues. Plasma‐based biomaterials are biologically active biomaterials made from platelet enriched plasma, which can be made into both solid and semi‐solid forms, are inexpensive, and are available as off‐the‐shelf, nonrefrigerated products. In this study, the use of plasma‐based biomaterials for the mitigation of acute and late toxicity for cutaneous radiation injury was investigated using a mouse model. A 2‐cm diameter circle of the dorsal skin was irradiated with a single dose of 35 Gy followed by topical treatment with plasma‐based biomaterial or vehicle once daily for 5 weeks postirradiation. Weekly imaging demonstrated more complete wound resolution in the plasma‐based biomaterial vs. vehicle group which became statistically significant (p < 0.05) at weeks 12, 13, and 14 postmaximum wound area. Despite more complete wound healing, at 9 and 17 weeks postirradiation, there was no statistically significant difference in collagen deposition or skin thickness between the plasma‐based biomaterial and vehicle groups based on Masson trichrome staining nor was there a statistically significant difference in inflammatory or fibrosis‐related gene expression between the groups. Although significant improvement was not observed for late toxicity, plasma‐based biomaterials were effective at promoting wound closure, thus helping to mitigate acute toxicity.

Crosstalk between neuropeptides SP and CGRP in regulation of BMP2-induced bone differentiation

AIM OF THE STUDY

The peripheral nervous system is involved in regulation of bone metabolism via sensory and sympathetic innervation. Substance P (SP) and calcitonin gene-related peptide (CGRP) are two sensory neuropeptides that have been associated with regulation of osteogenic differentiation. However, the interaction between SP and CGRP both with each other and the bone morphogenetic protein 2 (BMP2) in regulation of osteogenic differentiation has not been studied. Therefore, the aim of this study was to investigate the interaction between SP and CGRP on BMP2-induced bone differentiation using model progenitor cells.

MATERIALS AND METHODS

C2C12 myoblasts and MC3T3 pre-osteoblasts were treated with SP and CGRP, both individually and in combination, in the presence of BMP2. The effects of the neuropeptides on BMP2-induced osteogenic differentiation were assessed by measuring alkaline phosphatase (ALP) activity, mineralization, and expression of osteogenic markers.

RESULTS

Both SP and CGRP enhanced BMP2 signaling, Runx2 mRNA expression, as well as mineralization in vitro. Co-stimulation with SP and CGRP resulted in down-regulation of BMP2-induced bone differentiation, suggesting potential crosstalk between the two neuropeptides in regulation of BMP2 signaling.

CONCLUSIONS

Based on the results shown here, CGRP can mitigate augmenting effects of SP on BMP2 signaling and the three pathways potentially converge on Runx2 to regulate BMP2-induced bone differentiation.

The CARMA3-Bcl10-MALT1 Signalosome Drives NFκB Activation and Promotes Aggressiveness in Angiotensin II Receptor-Positive Breast Cancer

The angiotensin II receptor AGTR1, which mediates vasoconstrictive and inflammatory signaling in vascular disease, is overexpressed aberrantly in some breast cancers. In this study, we established the significance of an AGTR1-responsive NFκB signaling pathway in this breast cancer subset. We documented that AGTR1 overexpression occurred in the luminal A and B subtypes of breast cancer, was mutually exclusive of HER2 expression, and correlated with aggressive features that include increased lymph node metastasis, reduced responsiveness to neoadjuvant therapy, and reduced overall survival. Mechanistically, AGTR1 overexpression directed both ligand-independent and ligand-dependent activation of NFκB, mediated by a signaling pathway that requires the triad of CARMA3, Bcl10, and MALT1 (CBM signalosome). Activation of this pathway drove cancer cell-intrinsic responses that include proliferation, migration, and invasion. In addition, CBM-dependent activation of NFκB elicited cancer cell-extrinsic effects, impacting endothelial cells of the tumor microenvironment to promote tumor angiogenesis. CBM/NFκB signaling in AGTR1⁺ breast cancer therefore conspires to promote aggressive behavior through pleiotropic effects. Overall, our results point to the prognostic and therapeutic value of identifying AGTR1 overexpression in a subset of HER2-negative breast cancers, and they provide a mechanistic rationale to explore the repurposing of drugs that target angiotensin II-dependent NFκB signaling pathways to improve the treatment of this breast cancer subset.Significance: These findings offer a mechanistic rationale to explore the repurposing of drugs that target angiotensin action to improve the treatment of AGTR1-expressing breast cancers. Cancer Res; 78(5); 1225-40. ©2017 AACR.

Perivascular extracellular matrix hydrogels mimic native matrix microarchitecture and promote angiogenesis via basic fibroblast growth factor

Extracellular matrix (ECM)-derived bioscaffolds have been shown to elicit tissue repair through retention of bioactive signals. Given that the adventitia of large blood vessels is a richly vascularized microenvironment, we hypothesized that perivascular ECM contains bioactive signals that influence cells of blood vessel lineages. ECM bioscaffolds were derived from decellularized human and porcine aortic adventitia (hAdv and pAdv, respectively) and then shown have minimal DNA content and retain elastin and collagen proteins. Hydrogel formulations of hAdv and pAdv ECM bioscaffolds exhibited gelation kinetics similar to ECM hydrogels derived from porcine small intestinal submucosa (pSIS). hAdv and pAdv ECM hydrogels displayed thinner, less undulated, and fibrous microarchitecture reminiscent of native adventitia, with slight differences in ultrastructure visible in comparison to pSIS ECM hydrogels. Pepsin-digested pAdv and pSIS ECM bioscaffolds increased proliferation of human adventitia-derived endothelial cells and this effect was mediated in part by basic fibroblast growth factor (FGF2). Human endothelial cells cultured on Matrigel substrates formed more numerous and longer tube-like structures when supplemented with pAdv ECM bioscaffolds, and FGF2 mediated this matrix signaling. ECM bioscaffolds derived from pAdv promoted FGF2-dependent in vivo angiogenesis in the chick chorioallantoic membrane model. Using an angiogenesis-focused protein array, we detected 55 angiogenesis-related proteins, including FGF2 in hAdv, pAdv and pSIS ECMs. Interestingly, 19 of these factors were less abundant in ECMs bioscaffolds derived from aneurysmal specimens of human aorta when compared with non-aneurysmal (normal) specimens. This study reveals that Adv ECM hydrogels recapitulate matrix fiber microarchitecture of native adventitia, and retain angiogenesis-related actors and bioactive properties such as FGF2 signaling capable of influencing processes important for angiogenesis. This work supports the use of Adv ECM bioscaffolds for both discovery biology and potential translation towards microvascular regeneration in clinical applications.

Biopatterned CTLA4/Fc Matrices Facilitate Local Immunomodulation, Engraftment, and Glucose Homeostasis After Pancreatic Islet Transplantation

Pancreatic islet transplantation (PIT) represents a potential therapy to circumvent the need for exogenous insulin in type 1 diabetes. However, PIT remains limited by lack of donor islets and the need for long-term multidrug immunosuppression to prevent alloimmune islet rejection. Our goal was to evaluate a local immunoregulatory strategy that sustains islet allograft survival and restores glucose homeostasis in the absence of systemic immunosuppression. Nanogram quantities of murine CTLA4/Fc fusion protein were controllably delivered within human acellular dermal matrix scaffolds using an inkjet-based biopatterning technology and cotransplanted with allogeneic islets under the renal capsule to create an immunoregulatory microenvironment around the islet allograft. We achieved long-term engraftment of small loads of allogeneic islet cells with 40% of MHC-mismatched mouse recipients maintaining sustained normoglycemia following pancreatic β-cell ablation by streptozotocin. Biopatterned CTLA4/Fc local therapy was associated with expansion of Foxp3⁺ regulatory T cells and shifts in cytokine production and gene expression from proinflammatory to regulatory profiles, thus substantially benefiting islet allografts survival and function. This study is a new paradigm for targeted therapies in PIT that demonstrates the favorable effects of immune alterations in the transplant milieu and suggests a unique strategy for minimizing systemic immunosuppression and promoting islet allograft survival.

Transforming growth factor beta 1 augments calvarial defect healing and promotes suture regeneration

BACKGROUND

Repair of complex cranial defects is hindered by a paucity of appropriate donor tissue. Bone morphogenetic protein 2 (BMP2) and transforming growth factor beta 1 (TGFβ1) have been shown separately to induce bone formation through physiologically distinct mechanisms and potentially improve surgical outcome for cranial defect repair by obviating the need for donor tissue. We hypothesize that a combination of BMP2 and TGFβ1 would improve calvarial defect healing by augmenting physiologic osteogenic mechanisms.

METHODS/RESULTS

Coronal suturectomies (3×15 mm) were performed in 10-day-old New Zealand White rabbits. DermaMatrix™ (3×15mm) patterned with four treatments (vehicle, 350 ng BMP2, 200 ng TGFβ1, or 350 ng BMP2+200 ng TGFβ1) was placed in suturectomy sites and rabbits were euthanized at 6 weeks of age. Two-dimensional (2D) defect healing, bone volume, and bone density were quantified by computed tomography. Regenerated bone was qualitatively assessed histologically. One-way analysis of variance revealed significant group main effects for all bone quantity measures. Analysis revealed significant differences in 2D defect healing, bone volume, and bone density between the control group and all treatment groups, but no significant differences were detected among the three growth factor treatment groups. Qualitatively, TGFβ1 treatment produced bone with morphology most similar to native bone. TGFβ1-regenerated bone contained a suture-like tissue, growing from the lateral edge of the defect margin toward the midline. Unique to the BMP2 treatment group, regenerated bone contained lacunae with chondrocytes, demonstrating the presence of endochondral ossification.

CONCLUSIONS/SIGNIFICANCE

Total healing in BMP2 and TGFβ1 treatment groups is not significantly different. The combination of BMP2+TGFβ1 did not significantly increase bone healing compared with treatment with BMP2 or TGFβ1 alone postoperatively at 4 weeks. We highlight the potential use of TGFβ1 to regenerate calvarial bone and cranial sutures. TGFβ1 therapy significantly augmented bony defect healing at an earlier time point when compared with control, regenerated bone along the native intramembranous ossification pathway, and (unlike BMP2 alone or in combination with TGFβ1) permitted normal suture reformation. We propose a novel method of craniofacial bone regeneration using low-dose, spatially controlled growth factor therapies to minimize potentially harmful effects while maximizing local bioavailability and regenerating native tissues.

An engineered approach to stem cell culture: automating the decision process for real-time adaptive subculture of stem cells

Current cell culture practices are dependent upon human operators and remain laborious and highly subjective, resulting in large variations and inconsistent outcomes, especially when using visual assessments of cell confluency to determine the appropriate time to subculture cells. Although efforts to automate cell culture with robotic systems are underway, the majority of such systems still require human intervention to determine when to subculture. Thus, it is necessary to accurately and objectively determine the appropriate time for cell passaging. Optimal stem cell culturing that maintains cell pluripotency while maximizing cell yields will be especially important for efficient, cost-effective stem cell-based therapies. Toward this goal we developed a real-time computer vision-based system that monitors the degree of cell confluency with a precision of 0.791±0.031 and recall of 0.559±0.043. The system consists of an automated phase-contrast time-lapse microscope and a server. Multiple dishes are sequentially imaged and the data is uploaded to the server that performs computer vision processing, predicts when cells will exceed a pre-defined threshold for optimal cell confluency, and provides a Web-based interface for remote cell culture monitoring. Human operators are also notified via text messaging and e-mail 4 hours prior to reaching this threshold and immediately upon reaching this threshold. This system was successfully used to direct the expansion of a paradigm stem cell population, C2C12 cells. Computer-directed and human-directed control subcultures required 3 serial cultures to achieve the theoretical target cell yield of 50 million C2C12 cells and showed no difference for myogenic and osteogenic differentiation. This automated vision-based system has potential as a tool toward adaptive real-time control of subculturing, cell culture optimization and quality assurance/quality control, and it could be integrated with current and developing robotic cell cultures systems to achieve complete automation.

Bioprinting of growth factors onto aligned sub-micron fibrous scaffolds for simultaneous control of cell differentiation and alignment

The capability to spatially control stem cell orientation and differentiation simultaneously using a combination of geometric cues that mimic structural aspects of native extracellular matrix (ECM) and biochemical cues such as ECM-bound growth factors (GFs) is important for understanding the organization and function of musculoskeletal tissues. Herein, oriented sub-micron fibers, which are morphologically similar to musculoskeletal ECM, were spatially patterned with GFs using an inkjet-based bioprinter to create geometric and biochemical cues that direct musculoskeletal cell alignment and differentiation in vitro in registration with fiber orientation and printed patterns, respectively. Sub-micron polystyrene fibers (diameter ~ 655 nm) were fabricated using a Spinneret-based Tunable Engineered Parameters (STEP) technique and coated with serum or fibrin. The fibers were subsequently patterned with tendon-promoting fibroblast growth factor-2 (FGF-2) or bone-promoting bone morphogenetic protein-2 (BMP-2) prior to seeding with mouse C2C12 myoblasts or C3H10T1/2 mesenchymal fibroblasts. Unprinted regions of STEP fibers showed myocyte differentiation while printed FGF-2 and BMP-2 patterns promoted tenocyte and osteoblast fates, respectively, and inhibited myocyte differentiation. Additionally, cells aligned along the fiber length. Functionalizing oriented sub-micron fibers with printed GFs provides instructive cues to spatially control cell fate and alignment to mimic native tissue organization and may have applications in regenerative medicine.

Endoscopic transnasal cryo-assisted removal of an orbital cavernous hemangioma: a technical note

The cryoprobe device is commonly used by orbital surgeons for the extraction of intraorbital lesions. Cryoprobes provide a safe mechanism to manipulate fluid-filled tumors. Such lesions can present in locations in which intraoperative neurosurgical assistance is essential. The authors describe a technique whereby removal of an orbital hemangioma was facilitated by the aid of an endoscopic, transnasal cryoprobe while standard microsurgical dissection was performed concurrently via a transconjunctival approach.