Growth Plate Pathology in the Mucopolysaccharidosis Type VI Rat Model-An Experimental and Computational Approach

Maternal alloxan exposure induces damage in rat offspring lumbar vertebrae and protective role of arachidonic acid

BACKGROUND

Vertebral abnormalities in offspring of diabetic mothers make major challenges worldwide and were not sufficiently studied before.

AIM

To investigate the effects of alloxan-induced diabetes on rats' lumbar vertebrae, and to assess the potential beneficial impact of arachidonic acid.

MATERIALS AND METHODS

Pregnant rats were randomly equally divided into four groups: control, alloxan-induced diabetes received alloxan injection 150 mg∕kg, alloxan + arachidonic acid group received arachidonic acid 10 μg∕animal then given alloxan injection, and arachidonic acid group received it, until offspring age of three weeks. Six male offspring from each group were included in this study at ages of newborn, three-week-old, two-month-old, and their body measurements were recorded. Lumbar vertebrae and pancreas specimens were examined by light microscopy, morphometry, transmission electron microscopy (TEM), and immunohistochemistry for insulin expression.

RESULTS

In alloxan-induced diabetes newborn, three-week-old, and two-month-old rats, body measurements were significantly declined, histomorphometry of 6th lumbar vertebrae revealed disorganized chondrocytes, with vacuolated cytoplasm, empty lacunae, diminished matrix staining, with areas devoid of cells. TEM showed shrunken reserve and proliferative cells, with irregular nuclei, and damaged mitochondria. In contrast, alloxan + arachidonic acid group had cytoarchitecture of lumbar vertebrae that were like control group. Histomorphometry of pancreas in alloxan-induced diabetes group showed significant reduction in pancreatic islets number and surface area, damaged pancreatic islet cells appeared atrophied with apoptotic nuclei, and very weak insulin immunostaining. Whereas alloxan + arachidonic acid group displayed healthy features of pancreatic islets, which resembled control group, with strong insulin immunostaining.

CONCLUSIONS

Arachidonic acid mitigated alloxan-induced diabetes by its antidiabetic activity.

Treatment of skeletal and non-skeletal alterations of Mucopolysaccharidosis type IVA by AAV-mediated gene therapy

Mucopolysaccharidosis type IVA (MPSIVA) or Morquio A disease, a lysosomal storage disorder, is caused by N-acetylgalactosamine-6-sulfate sulfatase (GALNS) deficiency, resulting in keratan sulfate (KS) and chondroitin-6-sulfate accumulation. Patients develop severe skeletal dysplasia, early cartilage deterioration and life-threatening heart and tracheal complications. There is no cure and enzyme replacement therapy cannot correct skeletal abnormalities. Here, using CRISPR/Cas9 technology, we generate the first MPSIVA rat model recapitulating all skeletal and non-skeletal alterations experienced by patients. Treatment of MPSIVA rats with adeno-associated viral vector serotype 9 encoding Galns (AAV9-Galns) results in widespread transduction of bones, cartilage and peripheral tissues. This led to long-term (1 year) increase of GALNS activity and whole-body correction of KS levels, thus preventing body size reduction and severe alterations of bones, teeth, joints, trachea and heart. This study demonstrates the potential of AAV9-Galns gene therapy to correct the disabling MPSIVA pathology, providing strong rationale for future clinical translation to MPSIVA patients.