BackgroundIntrauterine adhesions (IUA) are the most common cause of uterine infertility and are caused by endometrium fibrotic regeneration following severe damage to the endometrium. Although current stem cell treatment options using different types of autologous stem cells have exhibited some beneficial outcomes in IUA patients, the reported drawbacks include variable therapeutic efficacies, invasiveness and treatment unavailability. Therefore, the development of new therapeutic stem cell treatments is critical to improving clinical outcomes.MethodsTwenty-six patients who suffered from infertility caused by recurrent IUA were enrolled in this prospective, non-controlled, phase I clinical trial with a 30-month follow-up. During the procedure, 1 × 107 umbilical cord-derived mesenchymal stromal cells (UC-MSCs), loaded onto a collagen scaffold, were transplanted into the uterine cavity following an adhesion separation procedure. Medical history, physical examination, endometrial thickness, intrauterine adhesion score and the biological molecules related to endometrial proliferation and differentiation were assessed both before and 3 months after cell therapy.ResultsNo treatment-related serious adverse events were found. Three months after the operation, the average maximum endometrial thickness in patients increased, and the intrauterine adhesion score decreased compared to those before the treatment. A histological study showed the upregulation of ERα (estrogen receptor α), vimentin, Ki67 and vWF (von Willebrand factor) expression levels and the downregulation of ΔNP63 expression level, which indicates an improvement in endometrial proliferation, differentiation and neovascularization following treatment. DNA short tandem repeat (STR) analysis showed that the regenerated endometrium contained patient DNA only. By the end of the 30-month follow-up period, ten of the 26 patients had become pregnant, and eight of them had delivered live babies with no obvious birth defects and without placental complications, one patient in the third trimester of pregnancy, and one had a spontaneous abortion at 7 weeks.ConclusionsTransplanting clinical-grade UC-MSCs loaded onto a degradable collagen scaffold into the uterine cavity of patients with recurrent IUA following adhesiolysis surgery is a safety and effective therapeutic method.Trial registrationClinicaltrials.gov. NCT02313415, Registered December 6, 2014.Electronic supplementary materialThe online version of this article (10.1186/s13287-018-0904-3) contains supplementary material, which is available to authorized users.

Fertilin ␤ (also known as ADAM2) is a cell adhesion molecule on the surface of mammalian sperm that participates in sperm-egg membrane binding. Fertilin ␤ is a member of the molecular family known as ADAMs or MDCs. These proteins have a disintegrin domain with homology to integrin ligands found in snake venoms; several of these snake proteins have an RGD tripeptide presented on an extended "disintegrin loop." However, fertilin ␤ lacks an RGD tripeptide and instead has the consensus sequence X(D/E)ECD (QDECD in mouse fertilin ␤) in its putative disintegrin loop, and there is controversy over which amino acids comprise the active site of the fertilin ␤ disintegrin loop. We have used point-mutated versions of the sequence AQDECDVT and two bioassays to identify the key functional amino acids of this sequence from the mouse fertilin ␤ disintegrin domain. Amino acid substitutions for the terminal aspartic acid residue of the QDECD sequence result in dramatically reduced activities in the two assays for protein function, implicating the terminal aspartic acid residue as critical for protein function. Substitutions for the glutamic acid and the cysteine residues in the QD-ECD sequence result in slight reductions in activity, whereas substitution of the first aspartic acid has virtually no effect. These data suggest that the conserved ECD sequence of the mouse fertilin ␤ disintegrin loop, especially the terminal D residue, contributes more to the protein's activity than does the QDE sequence that aligns with the RGD tripeptide in other disintegrins.The interactions of gamete plasma membranes are mediated by multiple cell adhesion molecules on the surfaces of the sperm and egg. One of these cell adhesion molecules is the mammalian sperm protein fertilin ␤ (previously known as PH-30; also known as ADAM2). The involvement of fertilin ␤ in sperm-egg adhesion during fertilization is well established based on studies with synthetic peptides, antibodies, recombinant proteins, and the subfertile phenotype of male fertilin ␤ knock-out mice (summarized in Ref. 1). Of particular interest is the domain of fertilin ␤ that has homology to a family of integrin ligands originally identified in snake venoms. This domain of fertilin ␤, known as the disintegrin domain, has been implicated in the interactions of fertilin ␤ with the egg membrane in a variety of species (2-9).A large number of disintegrin domain-containing proteins have been identified. These include members of the molecular family known as ADAMs (for A disintegrin and A metalloprotease) or MDCs (for metalloprotease/disintegrin/cysteine-rich) (10, 11), of which fertilin ␤ is a member. Disintegrin domains are also present in a number of snake venom proteins, which are called simply disintegrins, reprolysins, or snake venom metalloproteases. These snake venom polypeptides range in size from small peptide chains of Ͻ50 amino acids to multidomain proteins of several hundred amino acids that are similar in domain structure to ADAM proteins, having a metalloprotease domain and a cy...

Fertilin beta (also known as ADAM2), a mammalian sperm protein that mediates gamete cell adhesion during fertilization, is a member of the ADAM protein family whose members have disintegrin domains with homology to integrin ligands found in snake venoms. Fertilin beta utilizes an ECD sequence within its disintegrin domain to interact with the egg plasma membrane; the Asp is especially critical. Based on what is known about different integrin subfamilies and their ligands, we sought to characterize fertilin beta binding sites on mouse eggs, focusing on integrin subfamilies that recognize short peptide sequences that include an Asp residue: the alpha(5)/alpha(8)/alpha(v)/alpha(IIb) or RGD-binding subfamily (alpha(5)beta(1), alpha(8)beta(1), alpha(V)beta(1), alpha(V)beta(3), alpha(V)beta(5), alpha(V)beta(6), alpha(V)beta(8), and alpha(IIb)beta(3)) and the alpha(4)/alpha(9) subfamily (alpha(4)beta(1), alpha(9)beta(1), and alpha(4)beta(7)). We tested peptide sequences known to perturb interactions mediated by these integrins in two different assays for fertilin beta binding. Peptides with the sequence MLDG, which perturb alpha(4)/alpha(9) integrin-mediated interactions, significantly inhibit fertilin beta binding to eggs, which suggests a role for a member of this integrin subfamily as a fertilin beta receptor. RGD peptides, which perturb alpha(5)/alpha(8)/alpha(v)/alpha(IIb) integrin-mediated interactions, have partial inhibitory activity. The anti-alpha(6) antibody GoH3 has little or no inhibitory activity. An antibody to the integrin-associated tetraspanin protein CD9 inhibits the binding of a multivalent presentation of fertilin beta (immobilized on beads) but not soluble fertilin beta, which we speculate has implications for the role of CD9 in the strengthening of fertilin beta-mediated cell adhesion but not in initial ligand binding.

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