Begin by using a spreading technique with surgical scissors to carefully expose the airway of the procured pig lung. First, locate the largest airway which typically has a diameter of two to four centimeters. Then use a pair of forceps to palpate down the length of the airway to a depth of one inch.
Finally, hold the surgical scissors parallel to the airway and insert the closed tips into the tissue surrounding the unseen airway. Gently open the surgical scissors to pull apart the surrounding membrane. Take out the scissors and refrain from cutting any tissue.
Repeat this process intermittently to continue exposing the airway. Using the surgical scissors, cut the airway at the branching points and dissect along either branch independently. Sever regions of the airway once confident that the intact ends will remain identifiable and easily located.
Place severed regions of the airway into the corresponding tube, with the size of the severed regions ranging between one to five centimeters in length, and the width varying based on the relative location along the airway tree. Gently apply pressure to the vasculature to expose it and slowly pull it away from the airway. Allow the vasculature to stretch slightly and use surgical scissors to further separate it from the airway.
Avoid applying too much pressure as it may rip the vasculature. Once the branching point in the vascular tree has been exposed, insert the closed tips of the surgical scissors just below the branching point and between the two corresponding vasculature regions. Then slowly open the scissors to spread apart the underlying tissues.
Intermittently use a pair of tweezers to remove the tissue spread apart and any other tissue directly surrounding the vasculature. Cut the vasculature at a branching point when it covers regions of the airway or becomes cumbersome to any dissection step. Subsequently, dissect along either branch independently.
Confirm that the two ends of the vasculature remain identifiable and easily located for further dissection. Then sever the regions of the vasculature. To excise the alveolar tissue, locate a region of the tissue that is not in the vicinity of the airway or vasculature.
Pinch a small region of the tissue that appears to be devoid of vasculature or airway, and tear the pinched tissue from the lung. Alveolar tissue is present widely in the lung and should be removed throughout the dissection. Observe the region of tissue removed and confirm whether or not it is alveolar tissue.
This procedure was applied to a human lung model. A mass spectrometry analysis of the excised tissues indicated that ECM composition varies between individual regions of decellularized lungs, including whole lung ECM, alveolar enriched ECM, airway ECM, and vasculature ECM. In decellularized lungs obtained from patients with no history of lung disease, basement membrane associated proteins increased in alveolar enriched ECM.
At the same time, airway ECM was enriched in cartilage associated ECM protein such as aggrecan. The vasculature ECM was enhanced with fibronectin and other soluble ECM proteins associated with blood vessels.
