Biosynthesis and main biological properties of human gamma interferon

Conditions for and regularities of gamma-interferon production were elucidated. High interferon inducing activity of the known inductors such as concanavalin A, phytohemagglutinin and lentil lectin was asserted. It was shown that aqueous and alcoholic extracts of legumes seeds were also able to induce interferon synthesis in cultures of human peripheral blood leukocytes. By physicochemical properties such as stability to acids and liability to heating and by antigenic properties, interferon produced under such conditions was of type 2 (gamma). The maximum yield of interferon was observed in stationary and roller leukocyte cultures at a density of 2.10(6)-4.10(6) cells/ml on commercial rich media (IMDM and Eagle medium). Dynamics of gamma-interferon biosynthesis was determined. The peak of interferon production after the leukocyte induction with plant lectins was recorded in 72-96 hours.     

Some biological properties of human chorionic follicle stimulating hormone.

The biological properties of human chorionic FSH (hCFSH) for rat ovaries were investigated. Highly purified hCFSH had similar response to the ovarian augmentation test as bovine FSH and significantly enhanced 3H-thymidine uptake by granulosa cells and theca cells in the ovary of hypophysectomized rat. In contrast, highly purified hCG little responded to the ovarian augmentation test and had no effect on 3H-thymidine uptake by the ovary. These results indicate that hCFSH may promote the follicular growth of ovary resulting from granulosa cell proliferation and its enlargement. In addition, freshly harvested porcine granulosa cells were employed in an in vitro system to investigate specific binding of hCFSH to ovarian receptor. Radioiodinated hCFSH (125I-hCFSH) and hCG (125I-hCG) were respectively incubated with cell suspensions. Binding of these hormone preparations was proportional to the cell number and increased with the time of incubation through 120 minutes. The binding ability of 125I-hCFSH to the cells was greater than that of 125I-hCG. Increasing concentrations of unlabeled hCFSH in the incubation mixture progressively inhibited the uptake of 125I-hCFSH by granulosa cells. Unlabeled hCG was not able to compete with 125I-HCFSH binding. The similar phenomenon to inhibit the binding of 125I-hCG to the cells was also recognized in the presence of unlabeled hCG. These findings suggest that granulosa cell has at least two different types of receptor sites: one for hCFSH and the other for hCG.     

Supportive properties of basement membrane layer of human amniotic membrane enable development of tissue engineering applications

Human amniotic membrane (HAM) has been widely used as a natural scaffold in tissue engineering due to many of its unique biological properties such as providing growth factors, cytokines and tissue inhibitors of metalloproteinases. This study aimed at finding the most suitable and supportive layer of HAM as a delivery system for autologous or allogeneic cell transplantation. Three different layers of HAM were examined including basement membrane, epithelial and stromal layers. In order to prepare the basement membrane, de-epithelialization was performed using 0.5 M NaOH and its efficiency was investigated by histological stainings, DNA quantification, biomechanical testing and electron microscopy. Adipose-derived stromal cells (ASCs) and a human immortalized keratinocyte cell line (HaCaT) were seeded on the three different layers of HAM and cultured for 3 weeks. The potential of the three different layers of HAM to support the attachment and viability of cells were then monitored by histology, electron microscopy and (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Moreover, mechanical strengths of the basement membrane were assessed before and after cell culture. The results indicated that the integrity of extra cellular matrix (ECM) components was preserved after de-epithelialization and resulted in producing an intact basement amniotic membrane (BAM). Moreover, all three layers of HAM could support the attachment and proliferation of cells with no visible cytotoxic effects. However, the growth and viability of both cell types on the BAM were significantly higher than the other two layers. We conclude that growth stimulating effectors of BAM and its increased mechanical strength after culturing of ASCs, besides lack of immunogenicity make it an ideal model for delivering allogeneic cells and tissue engineering applications.     

Some physicochemical properties of plasma membrane vesicles.

The plasma membranes of many animal cells can be disrupted into small sealed vesicles that can be purified centrifugally and utilized for studies on membrane transport. The vesicles behave as micro-osmometers. However, the presence of charges fixed at the internal and external surfaces of the membrane walls produce pH levels at these surfaces that deviate considerably from bulk pH. Transverse symmetry of charge distribution further leads to transverse asymmetry of surface pH. Finally, charges fixed at the internal membrane surface produced significant Donnan osmotic effects that depend upon membrane composition and ionic environment.     

Intact human amniotic membrane differentiated towards the chondrogenic lineage

Human amniotic membrane (hAM) represents a tissue that is well established as biomaterial in the clinics with potential for new applications in regenerative medicine. For tissue engineering (TE) strategies, cells are usually combined with inductive factors and a carrier substrate. We have previously recognized that hAM represents a natural, preformed sheet including highly potent stem cells. In the present approach for cartilage regeneration we have induced chondrogenesis in hAM in vitro. For this, hAM biopsies were cultured for up to 56 days under chondrogenic conditions. The induced hAM was characterized for remaining viability, glycosaminoglycan (GAG) accumulation using histochemical analysis, and a quantitative assay. Collagen I, II and X was immunohistochemically determined and cartilage-specific mRNA expression of (sex determining region Y-) box 9, cartilage oligomeric matrix protein (COMP), aggrecan (AGC1), versican (CSPG2), COL1A1, COL9A2, melanoma inhibitory activity (MIA), and cartilage-linking protein 1 (CRTL1) analyzed by quantitative real-time polymerase chain reaction. Human AM was successfully induced to accumulate GAG, as demonstrated by Alcianblue staining and a significant (p < 0.001) increase of GAG/viability under chondrogenic conditions peaking in a 29.9 ± 0.9-fold induction on day 56. Further, upon chondrogenic induction collagen II positive areas were identified within histological sections and cartilage-specific markers including COMP, AGC1, CSPG2, COL1A1, COL9A2, MIA, and CRTL1 were found upregulated at mRNA level. This is the first study, demonstrating that upon in vitro induction viable human amnion expresses cartilage-specific markers and accumulates GAGs within the biomatrix. This is a promising first step towards a potential use of living hAM for cartilage TE.     

Charge properties of human pituitary and amniotic fluid prolactins.

The apparent isoelectric points (pI) in isoelectric focusing (IF) of human pituitary and amniotic fluid prolactin (hPRL), both non-iodinated and iodinated, were determined. Unresolved mixtures of pituitary hPRL isohormones E and F, and of at least five isohormones found in amniotic fluid, and plasma hPRL exhibit an average pI value of 6.5 - 6.7. Transient state pH values observed or previously reported for hPRL components range from pH 5.9 to 6.8 after correction to standard conditions. At pH 8.1, the major isohormone, hPRL-F, carriers a charge of 2.2 net protons per molecule. The net charge differences among isohormones E, F and G are compatible with acquisition or loss of single charged groups per 20,000 molecular weight. This net charge is similar to that of the least prolactin-bioactive major isohormone of human growth hormone (hGH-B), while the hGH with a bioactivity comparable to that of hPRL exhibits a net charge of 3.4 valence units. The "large" isohormones J and H increased net charges, by a factor of 2-3, in direct proportion to their size increments.     

A skin substitute based on human amniotic membrane

Human amniotic membrane (HAM) has biological properties which are useful for wound healing. HAM is notably one of the therapeutic alternatives for venous leg ulcer care. Indeed, a prospective clinical study has demonstrated that cryopreserved HAM transplantation for leg ulcer is feasible, safe and has beneficial effects: 80 % of the patients had a significant clinical response. Nevertheless, at the end of the 3-month follow-up period, only 20 % of the ulcers were totally closed. The aim of this work was to create and characterize a model of epidermized HAM. The method of HAM desepithelialization was validated by histology, immunohistochemistry and scanning electron microscopy. Then, de-epithelialized HAM was seeded with primary keratinocytes. After 21 days of culture, 15 at the air–liquid interface, the model obtained was analyzed histologically and by immunohistochemistry. The amniotic basement membrane was preserved during enzymatic desepithelialization of HAM. Primary keratinocytes proliferated on HAM: the model obtained showed involucrin expression and had a good basement membrane. As re-epithelialization is an important step for ulcer closure, a model of epidermized HAM could be used to speed up the healing of such wounds.     

Transfer of monovalent cations across the isolated human amniotic membrane]

When the conductance and the bi-ionic potential are measured in vitro, monovalent cations are transferred according to a simple diffusion mechanism across the amnion (from the inside to the outside of the amniotic cavity or in the reverse direction) in channels with neutral or negative fixed sites. For equal concentration, the permeability to K+ is superior to that of Na+.     

Culture of limbal stem cells on human amniotic membrane

Limbal stem cells (LSC) have an important role in the maintenance of the corneal surface epithelium, and autologous cultured limbal epithelial cell (HLECs) transplantations have contributed substantially to the treatment of the visually disabling condition known as LSC deficiency. A major challenge is the ability to identify LSC in vitro and in situ, and one of the major controversies in the field relates to reliable LSC markers. This study was carried out to evaluate the culture of a limbal biopsy on human amniotic membrane (HAM): directly on the chorionic side and on intact epithelium, and the expression of the stem cell associated markers: ABCG2, p63. HAM has been extensively used for ocular surface reconstruction and has properties which facilitate the growth of epithelial cells controlling inflammation and scarring.     

Some species of human leukocyte interferon are glycosylated

The carbohydrate content of all of the species of human leukocyte interferon (IFN-alpha) which have been derived from patients with chronic myelogeneous leukemia (CML) and purified to homogeneity has now been determined. Amino sugar content was measured by high-performance liquid chromatography and fluorescamine detection of acid hydrolysates of each sample. Two species showed significant amounts of glucosamine. Most of the purified species of leukocyte interferon from a myeloblast cell line were also tested, and two species were found to contain sugar residues. These forms also differed from the CML interferons in that they revealed the presence of greater amounts of galactosamine. The apparent lack of carbohydrate in some of the higher-molecular-weight species of interferon implicated factors other than glycosylation in the molecular weight differences. The results indicate that some species of IFN-alpha are glycosylated to various degrees.     

Physicochemical properties of non-activated and activated renin from human amniotic fluid.

The main physicochemical and enzymic properties of non-activated and activated human amniotic renin (EC 3.4.99.19) were studied in order to clarify the relationships between the two enzymes. Human amniotic renin was activated by dialysis against acidic buffer (pH 3.3), direct acidification or trypsin treatment. All procedures produced similar activation. The physicochemical characteristics of non-activated and activated renin were compared to those of human renal renin. Non-activated renin had a molecular weight of 45,500. A similar molecular weight was obtained by gel eluate activation and by acid treatment of renin prior to gel filtration. Similar isoelectric points were also found for non-activated and activated renin. One major renin peak focused at pH 6.6, whereas no similar renin peak was detected in extracts from normal human kidney. In addition, non-activated and activated renin forms were found to have the same optimal pH, the same Km and the same inhibiting pepstatin concentrations.