Combination product of dermal matrix, preconditioned human mesenchymal stem cells and timolol promotes wound healing in the porcine wound model.

A combination product of human mesenchymal stem/stromal cells (MSCs) embedded in an extracellular matrix scaffold and preconditioned with hypoxia and the beta-adrenergic receptor antagonist, timolol, combined with sustained timolol application post implantation, has shown promising results for improving wound healing in a diabetic mouse model. In the present study, we extend those findings to the more translatable large animal porcine wound model and show that the combined treatment promotes wound reepithelialization in these excisional wounds by 40.2% and increases the CD31 immunostaining marker of angiogenesis compared with the matrix control, while maintaining an accumulated timolol plasma concentration below the clinically safe level of 0.3 ng/mL after the 15-day course of topical application. Human GAPDH was not elevated in the day 15 wounds treated with MSC-containing device relative to wounds treated with matrix alone, indicating that the xenografted human MSCs in the treatment do not persist in these immune-competent animals after 15 days. The work demonstrates the efficacy and safety of the combined treatment for improving healing in the clinically relevant porcine wound model.

Combination product of dermal matrix, human mesenchymal stem cells, and timolol promotes diabetic wound healing in mice.

Diabetic foot ulcers are a major health care concern with limited effective therapies. Mesenchymal stem cell (MSC)-based therapies are promising treatment options due to their beneficial effects of immunomodulation, angiogenesis, and other paracrine effects. We investigated whether a bioengineered scaffold device containing hypoxia-preconditioned, allogeneic human MSCs combined with the beta-adrenergic antagonist timolol could improve impaired wound healing in diabetic mice. Different iterations were tested to optimize the primary wound outcome, which was percent of wound epithelialization. MSC preconditioned in 1 µM timolol at 1% oxygen (hypoxia) seeded at a density of 2.5 × 105 cells/cm2 on Integra Matrix Wound Scaffold (MSC/T/H/S) applied to wounds and combined with daily topical timolol applications at 2.9 mM resulted in optimal wound epithelialization 65.6% (24.9% ± 13.0% with MSC/T/H/S vs 41.2% ± 20.1%, in control). Systemic absorption of timolol was below the HPLC limit of quantification, suggesting that with the 7-day treatment, accumulative steady-state timolol concentration is minimal. In the early inflammation stage of healing, the MSC/T/H/S treatment increased CCL2 expression, lowered the pro-inflammatory cytokines IL-1B and IL6 levels, decreased neutrophils by 44.8%, and shifted the macrophage ratio of M2/M1 to 1.9 in the wound, demonstrating an anti-inflammatory benefit. Importantly, expression of the endothelial marker CD31 was increased by 2.5-fold with this treatment. Overall, the combination device successfully improved wound healing and reduced the wound inflammatory response in the diabetic mouse model, suggesting that it could be translated to a therapy for patients with diabetic chronic wounds.

Absorption and Safety of Topically Applied Timolol for Treatment of Chronic Cutaneous Wounds.

Objective: There are no safety or absorption studies to guide topical timolol therapy for treatment of chronic wounds. This study was undertaken to address this gap. Approach: A prospective, observational, cross-sectional comparative study of timolol plasma levels in patients after topical administration to a chronic wound, compared with levels in patients after timolol ocular administration for the indication of glaucoma. Results: There was no statistically significant difference in the average plasma level of timolol in wound as compared with glaucoma patients. No bradycardia or wheezing was observed after administration. Innovation: We determined the single time point concentration of timolol in plasma 1 h after application of timolol 0.5% gel-forming solution to debrided chronic wounds, providing insight as to the safety of this emerging off-label treatment. Conclusion: The topical application of timolol for chronic wounds shares the same safety profile as the widely used application of ocular administration for glaucoma.

Hypoxic pre-conditioning increases the infiltration of endothelial cells into scaffolds for dermal regeneration pre-seeded with mesenchymal stem cells.

Many therapies using mesenchymal stem cells (MSC) rely on their ability to produce and release paracrine signals with chemotactic and pro-angiogenic activity. These characteristics, however, are mostly studied under standard in vitro culture conditions. In contrast, various novel cell-based therapies imply pre-seeding MSC into bio-artificial scaffolds. Here we describe human bone marrow-derived MSC seeded in Integra matrices, a common type of scaffold for dermal regeneration (SDR). We show and measured the distribution of MSC within the SDR, where cells clearly establish physical interactions with the scaffold, exhibiting constant metabolic activity for at least 15 days. In the SDR, MSC secrete VEGF and SDF-1α and induce transwell migration of CD34(+) hematopoietic/endothelial progenitor cells, which is inhibited in the presence of a CXCR4/SDF-1α antagonist. MSC in SDR respond to hypoxia by altering levels of angiogenic signals such as Angiogenin, Serpin-1, uPA, and IL-8. Finally, we show that MSC-containing SDR that have been pre-incubated in hypoxia show higher infiltration of endothelial cells after implantation into immune deficient mice. Our data show that MSC are fully functional ex vivo when implanted into SDR. In addition, our results strongly support the notion of hypoxic pre-conditioning MSC-containing SDR, in order to promote angiogenesis in the wounds.

In Vitro Evaluation of Scaffolds for the Delivery of Mesenchymal Stem Cells to Wounds.

Mesenchymal stem cells (MSCs) have been shown to improve tissue regeneration in several preclinical and clinical trials. These cells have been used in combination with three-dimensional scaffolds as a promising approach in the field of regenerative medicine. We compare the behavior of human adipose-derived MSCs (AdMSCs) on four different biomaterials that are awaiting or have already received FDA approval to determine a suitable regenerative scaffold for delivering these cells to dermal wounds and increasing healing potential. AdMSCs were isolated, characterized, and seeded onto scaffolds based on chitosan, fibrin, bovine collagen, and decellularized porcine dermis. In vitro results demonstrated that the scaffolds strongly influence key parameters, such as seeding efficiency, cellular distribution, attachment, survival, metabolic activity, and paracrine release. Chick chorioallantoic membrane assays revealed that the scaffold composition similarly influences the angiogenic potential of AdMSCs in vivo. The wound healing potential of scaffolds increases by means of a synergistic relationship between AdMSCs and biomaterial resulting in the release of proangiogenic and cytokine factors, which is currently lacking when a scaffold alone is utilized. Furthermore, the methods used herein can be utilized to test other scaffold materials to increase their wound healing potential with AdMSCs.

Crosstalk between adrenergic and toll-like receptors in human mesenchymal stem cells and keratinocytes: a recipe for impaired wound healing.

Previous studies demonstrate that skin wounds generate epinephrine (EPI) that can activate local adrenergic receptors (ARs), impairing healing. Bacterially derived activators of Toll-like receptors (TLRs) within the wound initiate inflammatory responses and can also impair healing. In this study, we examined the hypothesis that these two pathways crosstalk to one another, using EPI and macrophage-activating lipopeptide-2 (MALP2) to activate ARs and TLR2, respectively, in human bone marrow-derived mesenchymal stem cells (BM-MSCs) and neonatal keratinocytes (NHKs). BM-MSCs exposed to EPI significantly (p < .05) increased TLR2 message (sevenfold BM-MSCs), TLR2 protein (twofold), and myeloid differentiation factor 88 (MyD88) (fourfold). Conversely, activation of TLR2 by MALP2 in these cells increased ß2-AR message (twofold in BM-MSCs, 2.7-fold in NHKs), ß2-AR protein (2.5-fold), phosphorylation of ß-AR-activated kinase (p-BARK, twofold), and induced release of EPI from both cell types (twofold). Treating cells with EPI and MALP2 together, as would be encountered in a wound, increased ß2-AR and p-BARK protein expression (sixfold), impaired cell migration (BM-MSCs- 21%↓ and NHKs- 60%↓, p < .002), and resulted in a 10-fold (BM-MSCs) and 51-fold (NHKs) increase in release of IL-6 (p < .001) responses that were remarkably reduced by pretreatment with ß2-AR antagonists. In vivo, EPI-stressed animals exhibited impaired healing, with elevated levels of TLR2, MyD88, and IL-6 in the wounds (p < .05) relative to nonstressed controls. Thus, our data describe a recipe for decreasing cell migration and exacerbating inflammation via novel crosstalk between the adrenergic and Toll-like receptor pathways in BM-MSCs and NHKs.

Acute wounding alters the beta2-adrenergic signaling and catecholamine synthetic pathways in keratinocytes.

Keratinocyte migration is critical for wound re-epithelialization. Previous studies showed that epinephrine activates the beta2-adrenergic receptor (B2AR), impairing keratinocyte migration. Here, we investigated the keratinocyte catecholamine synthetic pathway in response to acute trauma. Cultured keratinocytes were scratch wounded and expression levels of the B2AR and catecholamine synthetic enzymes tyrosine hydroxylase and phenylethanolamine-N-methyltransferase were assayed. The binding affinity of the B2AR was measured. Wounding downregulated B2AR, tyrosine hydroxylase, and phenylethanolamine-N-methyltransferase expression, but pre-exposure to timolol, a beta-adrenergic receptor antagonist, delayed this effect. In wounded keratinocytes, B2AR-binding affinity remained depressed even after its expression returned to prewounding levels. Keratinocyte-derived norepinephrine increased after wounding. Norepinephrine impaired keratinocyte migration; this effect was abrogated with B2AR-selective antagonist ICI-118,551 but not with B1AR-selective antagonist bisoprolol. Finally, for clinical relevance, we determined that norepinephrine was present in freshly wounded skin, thus providing a potential mechanism for impaired healing by local B2AR activation in wound-edge keratinocytes. Taken together, the data show that keratinocytes modulate catecholamine synthetic enzymes and release norepinephrine after scratch wounding. Norepinephrine appears to be a stress-related mediator that impairs keratinocyte migration through activation of the B2AR. Future therapeutic strategies evaluating modulation of norepinephrine-related effects in the wound are warranted.

Ovariectomy lowers urine levels of unconjugated (+)-catechin, (-)-epicatechin, and their methylated metabolites in rats fed grape seed extract.

Abstract Steroid hormones modulate expression of enzymes that metabolize xenobiotics, including dietary supplements. Half of the human population undergoes menopause, yet the effect of this age-related loss of ovarian steroid hormones on the metabolism of dietary supplements has yet to be determined. Grape seed extract (GSE) is a dietary supplement comprised of monomeric and oligomeric catechins and has health benefits in models of age-related diseases. We hypothesized that surgically-induced loss of ovarian hormones would increase methylation, glucuronidation, and/or sulfation of the grape seed polyphenols (+)-catechin and (-)-epicatechin. Fourteen-week-old spontaneously hypertensive rats (SHRs) were ovariectomized (OVX) or sham-OVX. At 17 weeks of age, SHRs were gavaged with vehicle (water) or GSE (300 mg/kg body weight) once daily for 6 days. Urinary excretion of (+)-catechin, (-)-epicatechin, and their metabolites was analyzed by liquid chromatography-mass spectrometry. Although total urinary output of (+)-catechin, (-)-epicatechin, and their methylated metabolites was unaffected by OVX, the amounts of (+)-catechin, (-)-epicatechin and their methylated metabolites that were not conjugated with glucuronic acid or sulfate were lowered by OVX. Specifically, urine from OVX SHRs administered GSE contained 30% higher proportions (91.8% vs. 62.3%) of glucuronidated (+)-catechin and (-)-epicatechin and glucuronidated methyl (+)-catechin and methyl (-)-epicatechin than urine from sham-OVX SHRs. However, there were no differences in urinary levels of total methylated or sulfated catechins in OVX SHRs. This is the first quantitative characterization of metabolites of grape seed polyphenols in a model of menopause; it indicates that ovariectomy causes either an increase in expression and/or activity of select uridine 5'-diphospho-glucuronosyltransferase(s).

The Xenopus laevis cortical granule lectin: cDNA cloning, developmental expression, and identification of the eglectin family of lectins.

A Xenopus laevis egg cortical granule, calcium-dependent, galactosyl-specific lectin participates in forming the fertilization layer of the egg envelope and functions in establishing a block to polyspermy. We report the cDNA cloning of the lectin, expression of the cortical granule lectin gene during oogenesis and early development, and identification of a new family of lectins. The translated cDNA for the cortical granule lectin had a signal peptide, a structural sequence of 298 amino acids, a molecular weight of 32.7 K, contained consensus sequence sites for N-glycosylation and a fibrinogen domain. The lectin cDNA was expressed during early stages of oogenesis. Lectin glycoprotein levels were constant during development with 2/3 of the lectin associated with the extracellular perivitelline space and the egg/embryo fertilization envelope. Lectin mRNA levels were from 100- to 1000-fold greater in ovary than in other adult tissues. The lectin had no sequence homology to the previously identified lectin families. The lectin had 41-88% amino acid identity with nine translated cDNA sequences from an ascidian, lamprey, frog, mouse, and human. Based on the conserved carbohydrate binding and structural properties of these glycoproteins, we propose a new family of lectins, the eglectin family.

Jeltraxin, a frog egg jelly glycoprotein, has calcium-dependent lectin properties and is related to human serum pentraxins CRP and SAP.

The egg jelly that encapsulates amphibian eggs is essential for fertilization, but its molecular composition and roles remain largely unknown. We identified a calcium-dependent lectin from the pentraxin superfamily in the egg jelly coat from the South American burrowing frog, Lepidobatrachus laevis. This lectin, jeltraxin, was related to the host-response acute phase serum proteins C-reactive P component (CRP) and serum amyloid P component (SAP). The amino acid sequence of jeltraxin is 44% identical to that of Xenopus laevis CRP, 31-35% identical to those of mammalian CRP and SAP, and 21-27% identical to those of the large fusion pentraxins. Expression of jeltraxin mRNA was restricted to the oviduct, which distinguishes it as the first serum-related pentraxin not expressed in the liver. Purified jeltraxin was previously shown to exist in an oligomeric complex of approximately 250 kDa comprised of self-associating subunits. We have demonstrated by MALDI-TOF that this configuration is due to a decameric complex of 27.7 kDa subunits. Biotinylated jeltraxin bound to the high-molecular mass components of the egg jelly in a calcium-dependent manner with specificity for beta-galactose residues. On the basis of homology modeling, we predict that jeltraxin will coordinate two calcium ions. The function of jeltraxin will likely be related to its calcium-dependent lectin properties.

Determination of N-glycosylation sites and site heterogeneity in glycoproteins.

An approach for the characterization of glycosylation sites and oligosaccharide heterogeneity in glycoproteins based on a combination of nonspecific proteolysis, deglycosylation, and matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FT MS) is described. Glycoproteins were digested with Pronase yielding primarily glycopeptides and amino acids. Nonglycosylated peptide fragments were susceptible to complete Pronase digestion to their constituent amino acids. Steric hindrance prohibited the digestion of the peptide moiety attached to the glycan. Glycopeptides were desalted and concentrated using solid-phase extraction and analyzed by MALDI MS. The oligosaccharides were also analyzed by MALDI MS after releasing the glycans from glycoproteins using PNGase F. The peptide moiety of the glycopeptides was identified by subtracting the masses of the glycans derived from PNGase F treatment from the masses of the glycopeptides. The experimental strategy was validated using glycoproteins with known oligosaccharide structures, ribonuclease B and chicken ovalbumin. This procedure was then used to determine the N-glycosylation sites and site heterogeneity of a glycoprotein whose glycosylation pattern was unknown, namely, the Xenopus laevis egg cortical granule lectin. This procedure is useful for determining protein site heterogeneity and structural heterogeneities of the oligosaccharide moiety of glycoproteins.

The Primary Egg Envelope of the Anuran Lepidobatrachus laevis: Physicochemical and Macromolecular Alterations During Development: (egg envelopes).

The coelomic egg envelope (CE) of the frog Lepidobatrachus laevis has a network of fibrillar bundles which disperse after transit through the oviduct. Following oviposition, the egg vitelline envelope (VE) has an additional amorphous zone on the exterior surface. The fertilization envelope (FE) formed after fertilization, appears to be very similar to the VE. The CEs, VEs, FEs and hatched envelopes (FEh ) were manually isolated. The CE, VE and FE were solubilized at 100° using denaturing conditions, but were only partially solubilized in phosphate buffer, pH 7.0. All envelopes and several purified polypeptides from the VE and FE were analyzed using gel electrophoresis and one-dimensional peptide mapping. Each of the envelopes contained 9 major polypeptides ranging from 118.5 to 22 kD and 8-12 minor polypeptides. Several envelope components were added/removed in the conversions based on the results of experiments in which preparations were incubated with activated egg exudate and crude hatching enzyme; some of these transformations were mimicked by tryptic and chymotryptic digestions. Therefore, serine proteases may be involved in envelope processing in vivo. Lepidobatrachus CE polypeptides and several major components from the VE, FE and FEh were crossreactive with antibodies against Xenopus VE* .