Medium conditioned by human mesenchymal stromal cells reverses low serum and hypoxia-induced inhibition of wound closure.

Chronic wounds, such as pressure ulcers, are a common complication of impaired peripheral circulation, such as in advanced diabetes. Factors secreted by mesenchymal stromal cells (MSCs) have been shown to enhance wound healing in vitro and in vivo. However, there is little understanding of the impact of the chronic wound environment, namely the limited supply of nutrients and oxygen, on the ability of wound cells to respond to MSCs. In this study, we first established the effects of hypoxia (1% O2) and low serum (1% serum) concentration on the proliferation and migration of keratinocytes. We found that hypoxia and low serum significantly slowed down these processes. Next, we found that supplementation with human MSC-concentrated conditioned media (hMSC-CM) enhanced both cell migration and proliferation in the presence of hypoxia and low serum. Furthermore, low serum and hypoxia decreased cell spreading and F-actin expression, which was reversed in the presence of hMSC-CM. Several wound healing mediators were identified in hMSC-CM, including IL-5, IL-6, IL-8, IL-9, IP-10, MCP-1, FGF-2, and VEGF. This study suggests that the concentrated secretome of human MSCs can reverse the inhibitory effect of hypoxia and low serum on keratinocyte proliferation and migration. This phenomenon may contribute to the beneficial effects of hMSC-CM on wound healing in vivo.

In vitro inflammatory multi-cellular model of osteoarthritis.

Objective: Osteoarthritis (OA) is a chronic joint disease, with limited treatment options, characterized by inflammation and matrix degradation, and resulting in severe pain or disability. Progressive inflammatory interaction among key cell types, including chondrocytes and macrophages, leads to a cascade of intra- and inter-cellular events which culminate in OA induction. In order to investigate these interactions, we developed a multi-cellular in vitro OA model, to characterize OA progression, and identify and evaluate potential OA therapeutics in response to mediators representing graded levels of inflammatory severity. Methods: We compared macrophages, chondrocytes and their co-culture responses to "low" Interleukin-1 (IL-1) or "high" IL-1/tumor necrosis factor (IL-1/TNF) levels of inflammation. We also investigated response changes following the administration of dexamethasone (DEX) or mesenchymal stromal cell (MSC) treatment via a combination of gene expression and secretory changes, reflecting not only inflammation, but also chondrocyte function. Results: Inflamed chondrocytes presented an osteoarthritic-like phenotype characterized by high gene expression of pro-inflammatory cytokines and chemokines, up-regulation of ECM degrading proteases, and down-regulation of chondrogenic genes. Our results indicate that while MSC treatment attenuates macrophage inflammation directly, it does not reduce chondrocyte inflammatory responses, unless macrophages are present as well. DEX however, can directly attenuate chondrocyte inflammation. Conclusions: Our results highlight the importance of considering multi-cellular interactions when studying complex systems such as the articular joint. In addition, our approach, using a panel of both inflammatory and chondrocyte functional genes, provides a more comprehensive approach to investigate disease biomarkers, and responses to treatment.

A controlled release bupivacaine-alginate construct: Effect on chondrocyte hypertrophy conversion.

Objective: Osteoarthritis is a degenerative disease of the joint, affecting over 30 million people in the US1. A key characteristic of OA is chondrocyte hypertrophy, characterized by chondrocyte changes to a more rounded and osteoblastic phenotype, characterized by increased IL-6 and IL-8 secretion2. While there are no cures for OA, treatments focus on mitigating pain and inflammation, the two main symptoms of OA. However, the analgesics, NSAIDS and corticosteroids commonly used, do not target regeneration and have negative side effects. Local anesthetics (LA) can be used as a pain management alternative but are usually short lasting and therefore, not suited for chronic conditions such as OA. Our engineered sustained release local anesthetic construct successfully delivers bupivacaine for an extended period of time3-5. This study is designed to evaluate the effect of the LA system on chondrocytes in an inflammatory OA-like environment. Design: Chondrocytes were cultured with bolus, liposomal, or construct LA and either untreated or treated with TNF-α and IL-1α for 24 hrs, 48 hrs, or 96 hrs. Chondrocyte viability, interleukin-8 (IL-8), interleukin-6 (IL-6), collagenase activity and proteoglycan deposition were assessed. Results: In the presence of the engineered construct, the chondrocytes retained viability and regenerative function. Moreover, the construct allowed for higher initial doses to be used, which promoted more regeneration and decreased inflammation without compromising cellular viability. Conclusions: The construct promotes a less hypertrophic chondrocyte environment while promoting a more anti-inflammatory environment. These two factors are consistent with a less OA progressive environment when using the engineered construct, compared to bolus LA.

Recent Advances in the Use of Algal Polysaccharides for Skin Wound Healing.

BACKGROUND: Chronic skin wounds and pressure ulcers represent major health care problems in diabetic individuals, as well as patients who suffered a spinal cord injury. Current treatment methods are only partially effective and such wounds exhibit a high recurrence rate. Open wounds are at high risk of invasive wound infections, which can lead to amputation and further disability. An interdisciplinary approach is needed to develop new and more effective therapies. METHODS: The purpose of this work is to review recent studies focusing on the use of algal polysaccharides in commercially available as well as experimental wound dressings. Studies that discuss wound dressings based on algal polysaccharides, some of which also contain growth factors and even living cells, were identified and included in this review. RESULTS AND CONCLUSION: Algal polysaccharides possess mechanical and physical properties, along with excellent biocompatibility and biodegradability that make them suitable for a variety of applications as wound dressings. Furthermore, algal polysaccharides have been used for a dual purpose, namely as wound covering, but also as a vehicle for drug delivery to the wound site.

Alginate encapsulation for bupivacaine delivery and mesenchymal stromal cell immunomodulatory cotherapy.

PURPOSE: Mesenchymal stromal cells (MSCs) are used to treat various inflammatory conditions. In parallel, to mitigate pain associated with inflammation, analgesics or opioids are prescribed, often with significant side effects. Local anesthetics (LAs) offer a promising alternative to these medications. However, their short duration and negative effects on anti-inflammatory MSCs have limited their therapeutic effectiveness. To mitigate these negative effects and to move toward developing a cotherapy, we engineered a sustained release bupivacaine alginate-liposomal construct that enables up to 4 days of LA release. By encapsulating MSC in alginate (eMSC), we demonstrate that we can further increase drug concentration to clinically relevant levels, without compromising eMSC viability or anti-inflammatory function. MATERIALS AND METHODS: MSCs were freely cultured or encapsulated in alginate microspheres ± TNFα/IFN-γ and were left untreated or dosed with bolus, liposomal, or construct bupivacaine. After 24, 48, and 96 hours, the profiles were assessed to quantify secretory function associated with LA-MSC interactions. To approximate LA exposure over time, a MATLAB model was generated. RESULTS: eMSCs secrete similar levels of IL-6 and prostaglandin E2 (PGE2) regardless of LA modality, whereas free MSCs secrete larger amounts of IL-6 and lower amounts of anti-inflammatory PGE2. Modeling the system indicated that higher doses of LA can be used in conjunction with eMSC while retaining eMSC viability and function. In general, eMSC treated with higher doses of LA secreted similar or higher levels of immunomodulatory cytokines. CONCLUSION: eMSCs, but not free MSC, are protected from LA, regardless of LA modality. Increasing the LA concentration may promote longer and stronger pain mitigation while the protected eMSCs secrete similar, if not higher, immunomodulatory cytokine levels. Therefore, we have developed an approach, using eMSC and the LA construct that can potentially be used to reduce pain as well as improve MSC anti-inflammatory function.

Stimulus-responsive self-assembly of protein-based fractals by computational design.

Fractal topologies, which are statistically self-similar over multiple length scales, are pervasive in nature. The recurrence of patterns in fractal-shaped branched objects, such as trees, lungs and sponges, results in a high surface area to volume ratio, which provides key functional advantages including molecular trapping and exchange. Mimicking these topologies in designed protein-based assemblies could provide access to functional biomaterials. Here we describe a computational design approach for the reversible self-assembly of proteins into tunable supramolecular fractal-like topologies in response to phosphorylation. Guided by atomic-resolution models, we develop fusions of Src homology 2 (SH2) domain or a phosphorylatable SH2-binding peptide, respectively, to two symmetric, homo-oligomeric proteins. Mixing the two designed components resulted in a variety of dendritic, hyperbranched and sponge-like topologies that are phosphorylation-dependent and self-similar over three decades (~10 nm-10 µm) of length scale, in agreement with models from multiscale computational simulations. Designed assemblies perform efficient phosphorylation-dependent capture and release of cargo proteins.

Alginate-liposomal construct for bupivacaine delivery and MSC function regulation.

Mesenchymal stromal cell (MSC) therapies have become potential treatment options for multiple ailments and traumatic injuries. In the clinical setting, MSC are likely to be co-administered with local anesthetics (LA) which have been shown to have dose- and potency-dependent detrimental effects on the viability and function of cells. We previously developed and characterized a sustained-release LA delivery formulation comprised of alginate-encapsulated liposomal bupivacaine. The current studies were designed to evaluate the effect of this formulation on the secretion of three key MSC regulatory molecules, interleukin 6 (IL-6), prostaglandin E2 (PGE2), and transforming growth factor-beta 1 (TGF-ß1). MSCs were treated with several bupivacaine formulations-bolus, liposome, or alginate-liposome construct (engineered construct)-in the presence or absence of inflammatory stimulus to stimulate an injured tissue environment. Our results indicated that compared to bolus or liposomal bupivacaine, the engineered construct preserved or promoted MSC anti-inflammatory PGE2 secretion; however, the engineered construct did not increase TGF-ß1 secretion. Bupivacaine release profile analyses indicated that mode of drug delivery controlled the LA concentration over time and pathway analysis identified several shared and cytokine-specific molecular mediators for IL-6, PGE2, and TGF-ß1 which could explain differential MSC secretion responses in the presence of bupivacaine. Collectively, these studies support the potential utility of alginate-encapsulated LA constructs for anti-inflammatory cell therapy co-administration and indicate that mode of local anesthetic delivery can significantly alter MSC secretome function.

The growing role of precision and personalized medicine for cancer treatment.

Cancer is a devastating disease that takes the lives of hundreds of thousands of people every year. Due to disease heterogeneity, standard treatments, such as chemotherapy or radiation, are effective in only a subset of the patient population. Tumors can have different underlying genetic causes and may express different proteins in one patient versus another. This inherent variability of cancer lends itself to the growing field of precision and personalized medicine (PPM). There are many ongoing efforts to acquire PPM data in order to characterize molecular differences between tumors. Some PPM products are already available to link these differences to an effective drug. It is clear that PPM cancer treatments can result in immense patient benefits, and companies and regulatory agencies have begun to recognize this. However, broader changes to the healthcare and insurance systems must be addressed if PPM is to become part of standard cancer care.

The effect of local anesthetic on pro-inflammatory macrophage modulation by mesenchymal stromal cells.

Administering local anesthetics (LAs) peri- and post-operatively aims to prevent or mitigate pain in surgical procedures and after tissue injury in cases of osteoarthritis (OA) and other degenerative diseases. Innovative tissue protective and reparative therapeutic interventions such as mesenchymal stromal cells (MSCs) are likely to be exposed to co-administered drugs such as LAs. Therefore, it is important to determine how this exposure affects the therapeutic functions of MSCs and other cells in their target microenvironment. In these studies, we measured the effect of LAs, lidocaine and bupivacaine, on macrophage viability and pro-inflammatory secretion. We also examined their effect on modulation of the macrophage pro-inflammatory phenotype in an in vitro co-culture system with MSCs, by quantifying macrophage tumor necrosis factor (TNF)-α secretion and MSC prostaglandin E2 (PGE2) production. Our studies indicate that both LAs directly attenuated macrophage TNF-α secretion, without significantly affecting viability, in a concentration- and potency-dependent manner. LA-mediated attenuation of macrophage TNF-α was sustained in co-culture with MSCs, but MSCs did not further enhance this anti-inflammatory effect. Concentration- and potency-dependent reductions in macrophage TNF-α were concurrent with decreased PGE2 levels in the co-cultures further indicating MSC-independent macrophage attenuation. MSC functional recovery from LA exposure was assessed by pre-treating MSCs with LAs prior to co-culture with macrophages. Both MSC attenuation of TNF-α and PGE2 secretion were impaired by pre-exposure to the more potent bupivacaine and high dose of lidocaine in a concentration-dependent manner. Therefore, LAs can affect anti-inflammatory function by both directly attenuating macrophage inflammation and MSC secretion and possibly by altering the local microenvironment which can secondarily reduce MSC function. Furthermore, the LA effect on MSC function may persist even after LA removal.

Effect of Local Anesthetics on Human Mesenchymal Stromal Cell Secretion.

Anti-fibrotic and tissue regenerative mesenchymal stromal cell (MSC) properties are largely mediated by secreted cytokines and growth factors. MSCs are implanted to augment joint cartilage replacement and to treat diabetic ulcers and burn injuries simultaneously with local anesthetics, which reduce pain. However, the effect of anesthetics on therapeutic human MSC secretory function has not been evaluated. In order to assess the effect of local anesthetics on the MSC secretome, a panel of four anesthetics with different potencies - lidocaine, procaine, ropivacaine and bupivacaine - was evaluated. Since injured tissues secrete inflammatory cytokines, the effects of anesthetics on MSCs stimulated with tumor necrosis factor (TNF)-α and interferon (IFN)-γ were also measured. Dose dependent and anesthesia specific effects on cell viability, post exposure proliferation and secretory function were quantified using alamar blue reduction and immunoassays, respectively. Computational pathway analysis was performed to identify upstream regulators and molecular pathways likely associated with the effects of these chemicals on the MSC secretome. Our results indicated while neither lidocaine nor procaine greatly reduced unstimulated cell viability, ropivacaine and bupivacaine induced dose dependent viability decreases. This pattern was exaggerated in the simulated inflammatory environment. The reversibility of these effects after withdrawal of the anesthetics was attenuated for TNF-α/IFN-γ-stimulated MSCs exposed to ropivacaine and bupivacaine. In addition, secretome analysis indicated that constitutive secretion changes were clearly affected by both anesthetic alone and anesthetic plus TNFα/IFNγ cell stimulation, but the secretory pattern was drug specific and did not necessarily coincide with viability changes. Pathway analysis identified different intracellular regulators for stimulated and unstimulated MSCs. Within these groups, ropivacaine and bupivacaine appeared to act on MSCs similarly via the same regulatory mechanisms. Given the variable effect of local anesthetics on MSC viability and function, these studies underscore the need to evaluate MSC in the presence of medications, such as anesthetics, that are likely to accompany cell implantation.

Lysosomal membrane permeabilization by targeted magnetic nanoparticles in alternating magnetic fields.

Lysosomal death pathways are being explored as alternatives of overcoming cancer tumor resistance to traditional forms of treatment. Nanotechnologies that can selectively target and induce permeabilization of lysosomal compartments in cells could become powerful medical tools. Here we demonstrate that iron oxide magnetic nanoparticles (MNPs) targeted to the epidermal growth factor receptor (EGFR) can selectively induce lysosomal membrane permeabilization (LMP) in cancer cells overexpressing the EGFR under the action of an alternating magnetic field (AMF). LMP was observed to correlate with the production of reactive oxygen species (ROS) and a decrease in tumor cell viability. Confocal microscopy images showed an increase in the cytosolic activity of the lysosomal protease cathepsin B. These observations suggest the possibility of remotely triggering lysosomal death pathways in cancer cells through the administration of MNPs which target lysosomal internalization pathways and the application of AMFs.