Bioactivity and composition of a preserved connective tissue matrix derived from human placental tissue.

There are a wide variety of extracellular matrices that can be used for regenerative purposes. Placental tissue-based matrices are quickly becoming an attractive option given the availability of the tissue source and the wide variety of bioactive molecules knows to exist in unprocessed placental tissues. As fresh placental tissues are seldom an option at the point of care, we examined both the composition and bioactivity of a commercially packaged flowable placental connective tissue matrix (FPTM) (BioECM® , Skye Biologics, Inc.) that was preserved by the proprietary HydraTek® process. The FPTM contained significant amounts of collagen and various growth factors such as bFGF, EGF, PDGF, KGF, and PIGF. In addition, it contained high levels of tissue inhibitors of metalloproteinases (TIMP-1 and 2) and molecules known to modulate the immune response including TGF-ß and IL-4. In terms of its bioactivity, the FPTM displayed the ability (1) to suppress INF-γ secretion in activated T-cells nearly fourfold over control media, (2) to inhibit methicillin resistant Staphylococcus aureus (MRSA) and Staphylococcus saprophyticus proliferation, (3) to increase the migration of adipose-derived stem cells (ASCs) nearly threefold over control media and (4) to adhere to ASCs in culture. When ASCs were exposed to FPTM in culture, the cells maintained healthy morphology and showed no significant changes in the expression of five genes involved in tissue growth and repair as compared to culture in standard growth media. © 2018 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2731-2740, 2018.

In silico analysis of heme oxygenase structural homologues identifies group-specific conservations.

Heme oxygenases (HO) catalyze the breakdown of heme, aiding the recycling of its components. Several other enzymes have homologous tertiary structures to HOs, while sharing little sequence homology. These homologues include thiaminases, the hydroxylase component of methane monooxygenases, and the R2 component of Class I ribonucleotide reductases (RNR). This study compared these structural homologues of HO, using a large number of protein sequences for each homologue. Alignment of a total of 472 sequences showed little sequence conservation, with no residues having conservation in more than 80% of aligned sequences and only five residues conserved in at least 60% of the sequences. Fourteen additional positions, most of which were critical for hydrophobic packing, displayed amino acid similarity of 60% or higher. Ten conserved sequence motifs were identified in HOs and RNRs. Phylogenetic analysis verified the existence of the four distinct groups of HO homologues, which were then analyzed by group entropy analysis to identify residues critical to the unique function of each enzyme. Other methods for determining functional residues were also performed. Several common index positions identified represent critical evolutionary changes that resulted in the unique function of each enzyme, suggesting potential targets for site-directed mutagenesis. These positions included residues that coordinate ligands, form the active sites, and maintain enzyme structure. ENZYMES: Heme oxygenase (EC 1.14.14.18), methane monooxygenase (EC 1.14.13.25), ribonucleotide reductase (EC 1.17.4.1), thiaminase II (EC 3.5.99.2).